General Principles Week 1 to 4 Flashcards

Question

TLO 3.4 Describe the morphological features of acute inflammation

Answer 1

5. Tissue necrosis: * In severe cases, localized tissue destruction

Answer 2

* Serous inflammation: Protein-rich fluid exudate * Fibrinous inflammation: Exudate rich in fibrin * Suppurative (purulent) inflammation: Formation of pus * Ulcers: Local defects in surface epithelium

Answer 3

Pathogenesis of chronic inflammation: * Persistent infection * Prolonged exposure to toxic agents * Autoimmune reactions * Recurrent acute inflammation

Answer 4

1. Cellular infiltrate: Predominance of mononuclear cells (lymphocytes, plasma cells, macrophages) 2. Tissue destruction: Ongoing damage due to inflammatory mediators 3. Repair: Attempts at healing through fibrosis and angiogenesis 4. Granulation tissue formation: New blood vessels and fibroblasts 5. Fibrosis: Excessive collagen deposition leading to scarring

Answer 5

Granulomatous inflammation is characterized by: 1. Formation of granulomas: Focal collections of activated macrophages 2. Epithelioid cells: Modified macrophages with abundant pink cytoplasm 3. Multinucleated giant cells: Fusion of epithelioid cells 4. Lymphocyte cuff: Surrounding the granuloma 5. Central necrosis: In some cases (e.g., tuberculosis) 6. Fibrosis: Surrounding the granuloma in later stages

Answer 6

* Foreign body granulomas * Immune granulomas (e.g., tuberculosis, sarcoidosis)

Answer 7

Complications of wound healing: 1. Excessive scarring or keloid formation 2. Wound dehiscence (separation of wound edges) 3. Infection 4. Chronic non-healing wounds

Answer 8

Factors affecting wound healing: 1. Local factors: * Infection * Poor blood supply * Foreign bodies * Mechanical stress 2. Systemic factors: * Age * Nutrition * Diabetes * Medications (e.g., steroids) * Smoking * Obesity * Stress

Answer 9

1. Hemostasis (immediate): * Vasoconstriction * Platelet aggregation * Fibrin clot formation 2. Inflammatory phase (1-4 days): * Neutrophil and macrophage infiltration * Removal of debris and bacteria 3. Proliferative phase (4-21 days): * Angiogenesis * Fibroblast proliferation * Collagen synthesis * Granulation tissue formation * Re-epithelialization 4. Remodeling phase (21 days to 1 year): * Collagen reorganization * Scar maturation * Gradual regain of tissue strength

Answer 10

Classification of neoplasms: 1. By behavior: * Benign * Malignant (cancer) * Potentially malignant (in situ) 2. By tissue of origin: Carcinomas: Originate from epithelial tissue (e.g., skin, lining of organs) Sarcomas: Originate from connective tissue (e.g., bone, muscle, cartilage) Leukemias: Cancers of the blood-forming cells (white blood cells, red blood cells, platelets) Lymphomas: Cancers of the lymphatic system (lymph nodes, spleen)

Answer 11

1. Slow growth rate 2. Well-circumscribed and often encapsulated 3. Resemblance to tissue of origin (well-differentiated) 4. Lack of invasion into surrounding tissues 5. No metastasis 6. Limited effect on host (unless in a critical location) 7. Generally good prognosis 8. Often can be surgically removed with low risk of recurrence

Answer 12

Features of malignant neoplasms: 1. Rapid, uncontrolled growth 2. Poorly circumscribed and invasive 3. Loss of differentiation (anaplasia) 4. Invasion of surrounding tissues 5. Ability to metastasize 6. Significant effect on host health 7. Poor prognosis if untreated 8. High risk of recurrence after treatment Examples: * Carcinomas: Lung cancer, breast cancer, colorectal cancer * Sarcomas: Osteosarcoma, leiomyosarcoma * Hematologic malignancies: Leukemias, lymphomas * Brain tumors: Glioblastoma multiforme

Answer 13

1. Growth rate: Benign - slow; Malignant - rapid 2. Differentiation: Benign - well-differentiated; Malignant - poorly differentiated 3. Capsule: Benign - often encapsulated; Malignant - not encapsulated 4. Invasion: Benign - no invasion; Malignant - invasive growth 5. Metastasis: Benign - no metastasis; Malignant - can metastasize 6. Prognosis: Benign - generally good; Malignant - often poor if untreated 7. Effect on host: Benign - limited; Malignant - significant 8. Recurrence: Benign - rare; Malignant - common 9. Nuclear features: Benign - normal; Malignant - abnormal (pleomorphism, hyperchromatism) 10. Mitotic activity: Benign - low; Malignant - high, often abnormal

Answer 14

1. Genetic factors: Inherited mutations (e.g., BRCA1/2 in breast cancer) 2. Age: Increased risk with advancing age 3. Tobacco use: Lung, mouth, throat cancers 1. Alcohol consumption: Liver, esophageal, breast cancers 2. Chronic infections: HPV (cervical cancer), Hepatitis B/C (liver cancer) 3. Environmental toxins: Asbestos (mesothelioma), UV radiation (skin cancer) 4. Diet: High red meat consumption (colorectal cancer) 5. Obesity: Increased risk for various cancers including breast and colon 6. Lack of physical activity: Increased risk for colon and breast cancers 7. Hormonal factors: Prolonged estrogen exposure (breast cancer) 8. Immunosuppression: Increased risk of various cancers 9. Occupational exposures: Certain chemicals, radiation

Answer 15

* Mechanism: Gain-of-function mutations in proto-oncogenes lead to increased cell proliferation or survival * Examples: 1. RAS: Constitutively active in many cancers, promoting cell growth and survival 2. MYC: Overexpressed in various cancers, enhancing cell proliferation 3. HER2/neu: Amplified in some breast cancers, leading to increased cell division

Answer 16

* Mechanism: Loss-of-function mutations result in uncontrolled cell growth * Examples: 1. TP53: "Guardian of the genome," regulates cell cycle and apoptosis 2. RB: Controls cell cycle progression 3. APC: Regulates cell adhesion and signal transduction in colon cells

Answer 17

* Mechanism: Mutations lead to genomic instability and accumulation of mutations * Examples: 1. BRCA1/2: Involved in double-strand break repair, mutations increase breast and ovarian cancer risk 2. MLH1/MSH2: Mismatch repair genes, mutations cause Lynch syndrome 3. XPA/XPC: Nucleotide excision repair genes, mutations cause xeroderma pigmentosum

Answer 18

* Definition: Formation of new blood vessels to supply the tumor * Process: 1. Tumor cells release pro-angiogenic factors (e.g., VEGF) 2. Endothelial cells are activated and proliferate 3. New blood vessels form and grow towards the tumor * Importance: Essential for tumor growth beyond 1-2 mm and facilitates metastasis * Therapeutic target: Anti-angiogenic drugs (e.g., bevacizumab) can inhibit tumor growth

Answer 19

* Definition: Spread of cancer cells from primary site to distant organs * Steps in metastasis: 1. Local invasion: Cancer cells break through basement membrane 2. Intravasation: Cells enter blood or lymphatic vessels 3. Survival in circulation: Cells resist immune attack and mechanical stress 4. Extravasation: Cells exit vessels at distant sites 5. Colonization: Cells adapt and grow in new environment

Answer 20

6. Epithelial-mesenchymal transition (EMT) 7. Matrix metalloproteinases (MMPs) 8. Adhesion molecules 9. Chemokines and their receptors * Common metastatic sites: Lungs, liver, bones, brain

Answer 21

1. Chemical carcinogens 2. Physical carcinogens (e.g., radiation, asbestos) 3. Biological carcinogens (e.g., viruses)

Answer 22

1. Direct-acting carcinogens 2. Indirect-acting carcinogens (procarcinogens)

Answer 23

Chemical carcinogenesis is a multi-step process involving initiation, promotion, and progression. Initiation involves the initial DNA damage caused by the carcinogen. Promotion stimulates the growth of initiated cells. Progression involves further genetic and epigenetic changes that lead to the development of a malignant tumor. 2. 1. Initiation: * Carcinogen or its metabolite interacts with DNA * Forms DNA adducts or causes mutations * Examples: Alkylating agents, polycyclic aromatic hydrocarbons (PAHs) 2. Promotion: * Stimulates proliferation of initiated cells * Does not directly damage DNA * Examples: Phorbol esters, phenobarbital 3. Progression: * Accumulation of additional genetic changes * Leads to increased growth and invasive potential

Answer 24

Specific mechanisms: 1. Direct DNA damage: Alkylating agents form DNA adducts 2. Metabolic activation: Procarcinogens (e.g., benzo[a]pyrene) are activated by cytochrome P450 enzymes 3. Generation of reactive oxygen species: Leads to oxidative DNA damage 4. Epigenetic changes: Altered DNA methylation or histone modifications 5. Interference with DNA repair: Some carcinogens inhibit DNA repair mechanisms This is for informational purposes only. For medical advice or diagnosis, consult a professional. Chemical carcinogens can cause cancer by damaging DNA, the genetic material within cells. Here's a simplified explanation of their mechanisms of action: 1. Direct DNA Damage: Direct Interaction: Some chemicals can directly react with DNA, causing: DNA strand breaks: These disrupt the integrity of the DNA molecule. DNA cross-linking: Chemical bonds form between different parts of the DNA strand, hindering normal cell function. Base modifications: Chemical groups can be added to or removed from DNA bases, altering their structure and function. 2. Indirect DNA Damage: Metabolic Activation: Many chemicals are not directly harmful but are converted into reactive metabolites within the body. This often happens in the liver through the action of enzymes called cytochrome P450. Reactive Metabolites: These activated forms of the chemical can then react with DNA, causing damage. Key Takeaways: Chemical carcinogens damage DNA in various ways, leading to mutations that can contribute to cancer development. Some chemicals directly damage DNA, while others require metabolic activation to become harmful. These mechanisms disrupt the normal cell cycle and can lead to uncontrolled cell growth and division, the hallmark of cancer.

Answer 25

1. Tobacco smoke components (e.g., nitrosamines, PAHs) 2. Aflatoxin B1 (produced by Aspergillus fungi) 3. Vinyl chloride (industrial chemical) 4. Benzene (solvent and industrial chemical) 5. Arsenic compounds (environmental contaminant) Chemical carcinogens are substances that can cause cancer by damaging DNA, the genetic material within cells. Here are some examples: Industrial Chemicals: Aromatic amines: Found in dyes, rubber, and some pharmaceuticals. Polycyclic aromatic hydrocarbons (PAHs): Present in tobacco smoke, coal tar, and grilled food. Vinyl chloride: Used in the production of PVC plastics. Asbestos: A mineral used in insulation and construction materials. Formaldehyde: Used in building materials, preservatives, and disinfectants. Environmental Pollutants: Air pollution: Includes particulate matter, nitrogen oxides, and other pollutants from vehicle exhaust and industrial emissions. Water pollution: Contaminated water can contain industrial chemicals, pesticides, and heavy metals. Soil contamination: Industrial waste and agricultural runoff can contaminate soil with harmful chemicals. Lifestyle Exposures: Tobacco smoke: Contains numerous carcinogens, including nicotine, tar, and PAHs. Alcohol consumption: Excessive alcohol consumption can increase the risk of certain cancers, such as liver cancer. Dietary factors: Processed meats, excessive red meat consumption, and diets low in fruits and vegetables can increase cancer risk. Medical Treatments: Chemotherapy drugs: Some chemotherapy drugs can increase the risk of secondary cancers. Radiation therapy: High doses of radiation can damage DNA and increase the risk of cancer.

Answer 26

Coagulative necrosis

Answer 27

The apoptotic cell attracts inflammatory cells

Answer 28

Fibrosis of the wall

Answer 29

Reversible injury

Answer 30

Clostridium perfringens

Answer 31

Epithelioid cells

Answer 32

Neutrophils

Answer 33

Unidirectional locomotion of WBC’s directed by chemoattractants

Answer 34

Langhans giant cell

Answer 35

Margination, rolling, firm adhesion, transmigration, chemotaxis, phagocytosis

Answer 36

Metaplasia

Answer 37

Migration of leukocytes through the vessel wall to the site of inflammation

Answer 38

Fat necrosis

Answer 39

Coagulative necrosis

Answer 40

Tuberculosis

Answer 41

Coagulative necrosis of cardiac myocytes with neutrophil infiltrate

Answer 42

Reversible Injury Cells Undergo cloudy swelling Cell Membrane Blebbing Mitochondria Swollen and vacuolated Nucleus Clumping of chromatin Myelin Figures Rare Endoplasmic Reticulum (ER) Swollen Lysosomes Intact

Answer 43

Irreversible Injury Cells Cell death occurs Cell Membrane Discontinuous Mitochondria Amorphous density and calcification Nucleus Pyknosis, karyorrhexis, karyolysis Myelin Figures Swollen with loss of ribosomes Endoplasmic Reticulum (ER) Swollen with loss of ribosomes Lysosomes Ruptured with release of enzymes

Answer 44

Cellular Events of Inflammation Caused/Mediated By Margination Stasis of blood with reduced shear stress on endothelial cells Rolling and Transient Adhesion Binding of selectins with their ligands Firm Adhesion and Transmigration Binding of integrins (LFA-1 & VLA-4) to IgS CAMs (ICAM, VCAM, and JAM) Binding of PECAM molecules Chemotaxis Bacterial products, cytokines, components of the complement system, and phospholipids Phagocytosis Interaction of TLRs (on phagocytes) with PAMPs (on the pathogen)

Answer 45

Cell Derived Mediators Functions Vasoactive Amines (Histamine, Serotonin) Vasodilation, increased vascular permeability, and smooth muscle contraction Nitric Oxide (NO) Smooth muscle relaxation, vasodilation, inhibits platelet function Cytokines Pro-inflammatory and anti-inflammatory action, functioning of the immune system, hematopoiesis, antiviral action, and acute phase response Eicosanoids Vasodilation & increased vascular permeability (PGI2 and prostacyclin), vasoconstriction & platelet aggregation (thromboxane, leukotriene) Reactive Oxygen Species Microbial killing, cell damage, and inflammatory response Lysosomal Enzymes Increase vascular permeability, chemotaxis of inflammatory cells, activation of complement components, degrade bacteria and extracellular matrix Platelet Activating Factor (PAF) Vasodilation, platelet activation, increased vascular permeability, and bronchoconstriction

Answer 46

Common Benign Tumors & Their Malignant Counterparts Epithelial Tissue Benign Tumor: Squamous cell papilloma Malignant Tumor: Squamous cell carcinoma Connective Tissue Fibrocyte Benign Tumor: Fibroma Malignant Tumor: Fibrosarcoma Cartilage Benign Tumor: Chondroma Malignant Tumor: Chondrosarcoma Bone Benign Tumor: Osteoma Malignant Tumor: Osteosarcoma Fat Benign Tumor: Lipoma Malignant Tumor: Liposarcoma Bone Marrow No benign tumor Malignant Tumor: Leukemia Lymph Node Benign Tumor: Lymphoma Malignant Tumor: Lymphosarcoma Blood Vessel Benign Tumor: Hemangioma Malignant Tumor: Hemangiosarcoma Muscle Tissue Smooth Muscle Benign Tumor: Leiomyoma Malignant Tumor: Leiomyosarcoma Skeletal Muscle Benign Tumor: Rhabdomyoma Malignant Tumor: Rhabdomyosarcoma

Answer 47

Retinoblastoma gene and TP53 gene mutations are examples of which mechanism that could lead to cancer? Increasing apoptosis Proto-oncogenes being converted to oncogenes Inactivation of tumor suppressor genes (selected) Mutation in DNA repair genes

Answer 48

Match the neoplasm with its description Squamous cell carcinoma: Malignant tumor of epithelial cells Chondroma: Benign tumor of cartilage Osteosarcoma: Malignant tumor of bone Leiomyoma: Benign tumor of smooth muscle Liposarcoma: Malignant tumor of adipocytes

Answer 49

Which of the following can cause chronic inflammation? Select all that apply: ☑ Persistent infection ☑ Autoimmune disorder ☐ Acute exposure to an environmental toxin ☑ Chronic exposure to an environmental toxin

Answer 50

What is the convergence point of both the intrinsic and extrinsic pathways of apoptosis? Initiator caspases activated

Answer 51

Match the cell adaptation to its description Hypertrophy: Increase in the size of cells Atrophy: Decrease in the size of cells Hyperplasia: Increase in the number of cells Metaplasia: Change to a different cell type

Answer 52

Continuous in males from puberty. Produces four functional spermatids from one primary spermatocyte. Takes ~64 days to complete. Results in small, motile gametes. Spermatogenesis is the process of producing sperm cells in males. It happens in the testes and involves several steps: 1. Formation of Sperm Cells: It starts with spermatogonia (stem cells), which divide to form immature sperm cells. 2. Meiosis: These immature cells undergo meiosis, a type of cell division that reduces the chromosome number by half, creating four haploid sperm cells. 3. Maturation: The haploid cells mature into fully functional sperm, gaining a tail for swimming and a head containing genetic material. Spermatogenesis ensures that sperm are ready for reproduction, carrying half the genetic information needed to form an offspring.

Answer 53

Oogenesis is the process of creating an egg, or ovum, in a female fetus. It starts in the ovaries around seven weeks into gestation. Process Primordial germ cells: In the female fetus, primordial germ cells (PGCs) colonize the ovaries. Mitosis: PGCs undergo mitosis to become oogonia. Oogonia become primary oocytes: Oogonia undergo maturation to become primary oocytes. Meiosis: Primary oocytes undergo meiosis, which separates paired chromosomes and chromatids. This results in a secondary oocyte, which will complete meiosis if fertilized. Ovulation: The secondary oocyte is released from the ovary during ovulation

Answer 54

Meiosis generates genetic variability primarily through two mechanisms: crossing over (genetic recombination) which occurs during prophase I, and independent assortment of chromosomes during metaphase I, where homologous chromosomes randomly align, leading to diverse combinations of alleles in the resulting gametes Independent assortment: Random alignment of chromosomes during metaphase I. Crossing over: Exchange of genetic material during prophase I. Random fertilization: Fusion of genetically diverse gametes.

Answer 55

Promotes adaptation, disease resistance, and species evolution.

Answer 56

Fertilization is the process where a sperm cell penetrates an ovum (egg), essentially merging their genetic material to create a zygote, which marks the beginning of a new individual's development; in simpler terms, it is when a sperm "penetrates the egg. Sperm penetrates the ovum. Pronuclei fuse to restore diploid chromosome number. Cortical reaction prevents polyspermy. Calcium triggers completion of meiosis II in the ovum.

Answer 57

Zygotic cleavage is the process of cell division that occurs after fertilization to create a multicellular embryo. It is a series of mitotic divisions that produce smaller cells called blastomeres Zygotic cleavage is the series of rapid cell divisions that occur after a zygote (fertilized egg) is formed. During this process: 1. Zygote to Blastomeres: The single-celled zygote divides into smaller cells called blastomeres without increasing in overall size. 2. No Growth Phase: The cleavage divisions lack a growth phase, meaning the total volume of the embryo remains the same while the cells become progressively smaller. 3. Formation of a Multicellular Structure: This process eventually forms a solid ball of cells (morula) or a hollow structure (blastula), depending on the organism. Zygotic cleavage lays the foundation for the later stages of embryonic development by creating the cells that will differentiate into tissues and organs.

Answer 58

"Blastogenesis" refers to the early stage of embryonic development where a fertilized egg (zygote) divides rapidly to form a blastocyst, characterized by the formation of a fluid-filled cavity called the blastocoel, with an inner cell mass (which will become the embryo) surrounded by an outer layer of cells called the trophoblast (which will develop into the placenta) Morula compacts and forms a blastocoel. Blastocyst develops (inner cell mass + trophoblast).

Answer 59

"Implantation" refers to the process where a blastocyst, a ball of cells developed from a fertilized egg, attaches to and burrows into the lining of the uterus (endometrium), marking the initial stage of pregnancy; essentially, it's the moment the embryo becomes embedded in the uterine wall and starts to develop further. Blastocyst hatches from the zona pellucida. Trophoblast attaches to and invades the endometrium. Syncytiotrophoblast completes implantation (day 11–12 post-fertilization).

Answer 60

Sign of failed implantation. Cramping and spotting after a failed implantation is your body expelling the embryo after it failed to attach to the uterine wall When implantation does not occur, a timely destruction of the fully developed endometrium leads to menstruation. Recurrent implantation failure (~10% in IVF). Causes: Immunological, thrombophilias, or embryo aneuploidy.

Answer 61

The three germ layers, ectoderm, mesoderm, and endoderm, are the primary cell layers that develop early in an embryo and give rise to all the different tissues and organs in the body; with the ectoderm forming the skin and nervous system, the mesoderm forming muscles, bones, and connective tissue, and the endoderm forming the lining of the digestive and respiratory systems. Breakdown: Ectoderm (Outer Layer): Develops into the epidermis (outer layer of skin), hair, nails, brain, spinal cord, and neural tissue. Mesoderm (Middle Layer): Develops into skeletal muscles, bones, cartilage, blood vessels, kidneys, and the reproductive organs. Endoderm (Inner Layer): Develops into the lining of the digestive tract, lungs, liver, pancreas, and other internal organs associated with the digestive system.

Answer 62

Ectoderm: Epidermis, sweat glands. Mesoderm: Kidney tubules, gonads. Endoderm: Gastrointestinal and respiratory tract lining. Serosal membranes: Primarily mesodermal origin.

Answer 63

TLO 2.2: Serosal Membranes Location: Line cavities and cover organs. Composition: Simple squamous epithelium + connective tissue. Function: Reduce friction. Produce lubricating fluid. Compartmentalize body cavities. Examples: Pleura, pericardium, peritoneum. Serous membranes line body cavities and cover organs in those cavities. They are made up of two layers of mesothelial cells and secrete a thin, watery fluid called serous fluid. Serous membranes reduce friction between organs and the walls of the body cavity. Location Serous membranes line the following cavities: Thoracic cavity: The pleura lines the thoracic cavity and covers the lungs Abdominal cavity: The peritoneum lines the abdominal cavity and covers the abdominal organs Pericardial cavity: The pericardium surrounds the heart Vaginal cavity: The tunica vaginalis surrounds the testes in males Composition Serous membranes are made up of two layers of mesothelial cells. The visceral layer covers the organ, while the parietal layer covers the cavity wall. Function Serous membranes reduce friction between organs and the walls of the body cavity. They also provide structural support and act as a protective barrier.

Answer 64

TLO 2.3: Epithelial Tissue Types **Simple squamous**: Lines blood vessels and body cavities, and regulates the passage of substances **Simple cuboidal:** Found in kidney tubules and glandular tissue, and secretes and absorbs substances **Simple columnar:** Lines the stomach and intestines, and absorbs and secretes substances **Stratified squamous:** Protects the body from microorganisms and water loss, and is the main component of the skin **Stratified cuboidal: **Found in the excretory ducts of sweat and salivary glands **Stratified columnar: **Found in the conjunctiva of the eyelids, and protects and secretes mucus **Pseudostratified columnar: **Found in the trachea and upper respiratory tract, and secretes mucus Simple squamous: Diffusion/filtration (e.g., alveoli). Simple cuboidal: Secretion/absorption (e.g., kidney tubules). Simple columnar: Absorption/secretion (e.g., intestinal lining). Stratified squamous: Protection (e.g., esophagus). Stratified cuboidal: Protection/secretion (e.g., sweat glands). Stratified columnar: Protection/secretion (e.g., male urethra). Pseudostratified columnar: Secretion/cilia action (e.g., respiratory tract).

Answer 65

TLO 2.4: Histological Identification Based on: Cell shape (squamous, cuboidal, columnar). Layers (simple, stratified). Specialized structures (cilia, microvilli). Cell shape Squamous: Flat shape, with a width greater than its height Cuboidal: Cube shape, with a width and height that are roughly equal Columnar: Column shape, with a width smaller than its height Layers Simple: One layer of cells Stratified: Two or more layers of cells Pseudostratified: Appears to be stratified, but is actually one layer of cells

Answer 66

TLO 2.5: Cell Junctions Tight junctions: Seal adjacent cells (e.g., blood-brain barrier). Adherens junctions: Anchor cells (e.g., epithelial sheets). Desmosomes: Strong adhesion (e.g., skin epidermis). Gap junctions: Cell communication (e.g., cardiac muscle). **Tight junctions:** Create a watertight seal between cells, preventing leakage of fluids and molecules between them, essentially acting as a barrier function; often found in epithelial tissues like the lining of the bladder or stomach. **Adherens junctions:** Anchor cells to each other by connecting to the actin cytoskeleton, providing structural support and allowing for cell-to-cell adhesion; involved in cell migration and tissue development. **Desmosomes:** Strong, spot-like junctions that connect the intermediate filaments of neighboring cells, providing strong mechanical stability and resisting shearing forces; commonly found in tissues experiencing high stress like skin. **Gap junctions:** Form channels between cells allowing for direct communication and passage of small molecules like ions, enabling rapid electrical signaling between cells

Answer 67

TLO 2.6: Glandular Tissue Exocrine glands: Simple: Single duct (e.g., sweat glands). Compound: Branched ducts (e.g., salivary glands). Endocrine glands: Secrete directly into bloodstream (e.g., thyroid). Exocrine glands secrete substances through ducts onto the body's surfaces, while endocrine glands secrete substances directly into the bloodstream. The pancreas is an organ that contains both exocrine and endocrine glands. Exocrine glands Pancreas: Secretes digestive enzymes into the duodenum, such as trypsinogen and chymotrypsinogen. The pancreas also secretes bicarbonate ions to neutralize acidic chyme. Sweat glands: Secrete sweat onto the body's surface Lacrimal glands: Secrete tears onto the body's surface Salivary glands: Secrete saliva onto the body's surface Mammary glands: Secrete milk onto the body's surface Endocrine glands Pituitary gland: Located in the brain, this gland secretes hormones that regulate metabolism, mood, and sexual reproduction. Thyroid gland: An endocrine gland that secretes hormones. Adrenal glands: Located on top of each kidney, these glands secrete hormones that regulate metabolism, blood pressure, and the body's stress response. Pineal gland: Located at the base of the brain, this gland secretes melatonin, which helps regulate sleep and circadian rhythms. Parathyroid glands: Located in the neck, these glands regulate calcium levels in the blood.

Answer 68

TLO 2.7: Exocrine Secretion Mechanisms Merocrine: Exocytosis (e.g., pancreatic enzymes). Apocrine: Cytoplasm released with secretion (e.g., mammary glands). Holocrine: Entire cell disintegrates (e.g., sebaceous glands). The most damaging type of secretion to cells is holocrine, whereas merocrine is the least damaging, and apocrine is in between them. Note: -Endocrine glands are the glands that release their secretions directly into the blood and hence they are known as ductless glands. **Merocrine** The most common type of gland, merocrine glands release secretions through exocytosis. This process doesn't damage the cell. Examples of merocrine glands include eccrine sweat glands, which are found in the palms of the hands and soles of the feet. **Apocrine** Apocrine glands release secretions by pinching off part of the cell membrane. This causes the cell to lose some of its cytoplasm. Examples of apocrine glands include mammary glands, which produce breast milk. **Holocrine** Holocrine glands release secretions by rupturing the cell membrane. This destroys the cell, causing the entire cell to become part of the secretion. Examples of holocrine glands include sebaceous glands, which produce sebum, an oily substance that lubricates the skin.

Answer 69

Mesoderm: A layer of cells in the middle of an organism. Mesenchyme: An embryonic connective tissue that comes from the mesoderm. Hematopoietic stem cells: Cells that produce all the cells in the blood. Mesoderm: Mesenchyme: Fibroblasts, adipocytes. Hematopoietic stem cells: Blood cells, immune cells.

Answer 70

TLO 3.2: Connective Tissue Cell Types **Fibroblasts:** ECM synthesis. **Adipocytes: **Fat storage. **Macrophages:** Phagocytosis. **Mast cells: **Inflammatory mediators. Plasma cells: Antibody production. Chondrocytes: Cartilage matrix maintenance. Osteoblasts/Osteocytes: Bone matrix maintenance. **1. Fibroblasts:** These cells are essential for producing and maintaining the *extracellular matrix*, which provides structural support to tissues. They are especially involved in *wound healing, creating collagen and other fibers.* **2. Adipocytes: **Also known as fat cells, adipocytes store energy in the form of fat. They play critical roles in metabolism, energy balance, and insulation. There are two types of adipocytes: white fat cells and brown fat cells. **3. Macrophages: **These are key players in the immune system, responsible for *detecting, engulfing, and destroying pathogens and dead cells*. They also stimulate other immune cells and are involved in inflammation and tissue repair. **4. Mast Cells**: Part of the immune system, mast cells play a pivotal role in* allergic reactions and inflammatory processes*. They release *histamine* and *other chemicals during immune response*s, contributing to inflammation. **5. Plasma Cells:** These are mature B-lymphocytes that produce *antibodies to fight against pathogens*. They are an essential component of the adaptive immune system. **6. Chondrocytes: **These cells are found in cartilage and are responsible for the synthesis and maintenance of *cartilage matrix*. They help maintain the structural integrity of cartilage tissue. **7. Osteoblasts/Osteocytes:** Osteoblasts are cells that form new bone, synthesizing and secreting the bone matrix. Once they become embedded in the matrix they create, they differentiate into osteocytes. Osteocytes maintain bone tissue and are crucial for bone health and remodeling.

Answer 71

Topic 4: Skeletal Tissue TLO 4.1: Bone Cell Types Osteoblasts: Bone-forming cells; synthesize and secrete bone matrix. Osteocytes: Mature bone cells; maintain bone tissue. Osteoclasts: Bone-resorbing cells; break down bone matrix. Bone lining cells: Inactive osteoblasts covering bone surfaces. **Osteoblasts** Create new bone by secreting collagen and other proteins that bind to calcium and phosphate from the bloodstream. **Osteocytes** Mature osteoblasts that maintain bone structure by regulating mineral concentration. They are the most common cell in bone and can live as long as the organism. **Osteoclasts** Large cells that break down bone by dissolving minerals and collagen. They are found at the surface of bone where resorption is occurring. **Bone lining** cells Protect bone surfaces from osteoclast activity when bone is not being remodeled. They also regulate the movement of minerals in and out of bone.

Answer 72

TLO 4.2: Bone Tissue Organization Compact bone: Dense, organized with osteons (Haversian systems). Spongy bone: Porous with trabeculae. Periosteum: Outer fibrous layer covering bones. Endosteum: Inner membrane lining bone cavities. Compact bone The dense, rigid outer layer of bone. It's made up of osteons, which are microscopic units of calcified matrix. Spongy bone The lighter, less dense inner layer of bone. It's made up of trabeculae and contains red bone marrow, which produces blood cells. Periosteum The tough, shiny membrane that covers the outer surface of most bones. It's made of connective tissue and bone-forming cells, and helps bones grow, heal, and repair. Endosteum The delicate membrane that lines the cavities within bones, such as the medullary cavity.

Answer 73

Intramembranous ossification is the process of creating bone tissue from connective tissue membranes. It's a key part of fetal development and continues until a person is about 25 years old. Intramembranous ossification: Intramembranous ossification: begins within fibrous connective tissue membranes formed by mesenchymal cells. Intramembranous ossification: Forms frontal, parietal, occipital, temporal, and clavicle bones. Occurs in flat bones (e.g., skull, clavicle). Mesenchymal cells differentiate directly into osteoblasts. No cartilage intermediate.

Answer 74

Endochondral ossification is a process that replaces cartilage with bone during fetal development and bone growth. It's one of the two main ways bone tissue is created in the mammalian skeletal system. Occurs in long bones and vertebrae. Cartilage model is replaced by bone. Growth plates enable longitudinal growth.

Answer 75

Intramembranous and endochondral ossification are similar processes that both create bone tissue. Similarities Both processes produce bone tissue. Both processes involve osteoblasts, which are cells that create bone. Both processes occur before birth. Differences Intramembranous ossification: Forms bones from connective tissue, such as the skull. Endochondral ossification: Forms bones from cartilage, such as long bones, short bones, and the ends of flat bones.

Answer 76

TLO 4.4: Common Bone Disorders Osteoporosis Bones become brittle and weak due to loss of bone density Can be caused by aging, hormonal changes, and poor diet Can be treated with medication or lifestyle changes Rickets and osteomalacia Bones become soft due to a lack of calcium or vitamin D Can be caused by poor diet, lack of sunlight, or an inability to absorb vitamin D Can be treated with vitamin supplements or a yearly vitamin D injection Paget's disease Bones become misshapen due to excessive bone resorption and disorganized bone growth Can affect the spine, pelvis, and skull Can progress in the preexisting site, but does not spread to other bones Other bone disorders include: Osteogenesis imperfecta, which makes bones brittle Renal osteodystrophy, which can be caused by kidney disease Familial hypophosphatemia, a hereditary disorder that causes low levels of phosphate in the blood Osteoporosis: Decreased bone density; increased fracture risk. Causes: Age, hormonal changes, lack of exercise, poor nutrition. Osteomalacia/Rickets: Inadequate mineralization. Causes: Vitamin D deficiency, calcium or phosphate imbalance. Paget’s disease: Abnormal remodelling. Causes: Genetic factors, viral infections. Osteomyelitis: Bone infection. Causes: Bacterial/fungal infections via bloodstream or injury.

Answer 77

The four main components of blood are plasma, red blood cells, white blood cells, and platelets. Plasma The liquid component of blood that carries blood cells throughout the body Plasma is yellowish in color Red blood cells Also known as erythrocytes, these cells carry oxygen from the lungs to the body's tissues Red blood cells are the most common type of cell in blood They are produced in bone marrow and have a diameter of about 6 micrometers White blood cells Also known as leukocytes, these cells help fight infections and disease There are several types of white blood cells, including lymphocytes, monocytes, eosinophils, basophils, and neutrophils Platelets Also known as thrombocytes, these small, colorless cell fragments help stop bleeding Platelets stick to the lining of blood vessels to help prevent or stop bleeding Blood cells are produced in bone marrow, a spongy material in the center of bones. Plasma: Liquid (55% of blood). Components: Water, proteins, electrolytes, nutrients, hormones, waste. Formed elements: Cellular (45% of blood). Includes: Erythrocytes, leukocytes, platelets.

Answer 78

Erythrocytes, leukocytes, neutrophils, lymphocytes, monocytes, eosinophils, basophils, and platelets are all types of blood cells. Erythrocytes Also known as red blood cells (RBCs) The most common type of blood cell Carry oxygen from the lungs to the body's tissues Contain hemoglobin, a protein that carries oxygen Leukocytes Also known as white blood cells (WBCs) Part of the immune system and help fight infection Types of leukocytes include lymphocytes, monocytes, eosinophils, basophils, and neutrophils Neutrophils A type of white blood cell that helps heal damaged tissue and resolve infections A lower than normal neutrophil count is called neutropenia Lymphocytes A type of white blood cell that helps the body make cells that fight infection and make antibodies Part of the adaptive immune system Monocytes A type of white blood cell that helps other white blood cells remove damaged tissue and gobble up bacteria, viruses, debris, and infectious organisms Eosinophils A type of white blood cell that kills parasites, destroys cancer cells, and helps the immune system with an allergic response Contain granules that contain antihistamine molecules and molecules toxic to parasitic worms Basophils A type of white blood cell that releases histamine if there is an allergic reaction and helps prevent blood clots Platelets Also known as thrombocytes, Help in blood clotting, and A low number of platelets is called thrombocytopenia. Erythrocytes: Oxygen transport; biconcave, no nucleus. Leukocytes: Immune defense. Neutrophils: Bacteria phagocytosis. Lymphocytes: Adaptive immunity (T/B cells). Monocytes: Phagocytosis, antigen presentation. Eosinophils: Parasite defense, allergic response. Basophils: Release inflammatory mediators. Platelets: Blood clotting; derived from megakaryocytes.

Answer 79

TLO 5.3: Myeloid vs. Lymphoid Cell Lines Myeloid cells give rise to various cells, including red blood cells, platelets, granulocytes (neutrophils, eosinophils, basophils), monocytes, and dendritic cells. Lymphoid cells produce lymphocytes, including B cells, T cells, and natural killer (NK) Myeloid: Includes: Erythrocytes, platelets, granulocytes, monocytes. Shorter lifespan. Lymphoid: Includes: T/B lymphocytes, NK cells. Primarily adaptive immunity.

Answer 80

Iron deficiency anemia, vitamin B12 deficiency, sickle cell anemia, and thalassemia are all types of anemia. Anemia is a blood disorder that occurs when your body doesn't have enough healthy red blood cells. **Iron deficiency anemia **Occurs when your body doesn't have enough iron to produce hemoglobin Can be caused by poor diet or blood loss Can be treated by eating iron-rich foods and foods rich in vitamin C **Vitamin B12 deficiency anemia **Occurs when your body doesn't have enough vitamin B12 Can be caused by inadequate intake or absorption issues Can be treated with vitamin B12 supplements, injections, or nose sprays **Sickle cell anemia **An inherited disease that can cause anemia Thalassemia An inherited disease that can cause anemia Beta-thalassemia minor is often discovered during a routine blood count **Other causes of anemia include: **Folate deficiency, Chronic diseases, Infections, Certain medications, Bleeding, and Bone marrow problems. **Symptoms of anemia include: **Weakness Dizziness Shortness of breath Headache Pale or yellow skin Chest pain Iron deficiency anemia: Insufficient iron; microcytic, hypochromic. Vitamin B12 deficiency: Impaired DNA synthesis; macrocytic, neurological symptoms. Sickle cell anemia: Hemoglobin mutation; sickle-shaped cells, crises. Thalassemia: Defects in globin chain production; microcytic anemia.

Answer 81

Excitability: When a muscle receives a signal from a nerve, it can respond by initiating a contraction. Contractility: This is the primary function of muscle tissue, where the muscle fibers shorten to generate force. Extensibility: Muscles can be stretched without tearing, allowing for flexibility in movement. Elasticity: After being stretched, a muscle can recoil back to its original length due to its elastic properties. Excitability: Respond to stimuli. Contractility: Shorten and generate force. Extensibility: Stretch without damage. Elasticity: Return to original length.

Answer 82

TLO 6.2: Muscle Cell Types Smooth muscle: Involuntary, non-striated (e.g., hollow organs, vessels). Skeletal muscle: Voluntary, striated (e.g., attached to bones). Cardiac muscle: Involuntary, striated (e.g., heart). Smooth muscle: Found in the walls of internal organs like the stomach, bladder, and blood vessels, responsible for involuntary movements like digestion and blood pressure regulation; appears smooth under a microscope due to lack of striations. Skeletal muscle: Attached to bones, responsible for voluntary movements like walking and lifting; appears striated under a microscope and is controlled by the somatic nervous system. Cardiac muscle: Located only in the heart, responsible for pumping blood throughout the body; appears striated like skeletal muscle, but is involuntary and controlled by the autonomic nervous system. Key differences: Control: Smooth and cardiac muscles are involuntary, while skeletal muscle is voluntary. Location: Skeletal muscles are attached to bones, while smooth muscle is found in internal organs and cardiac muscle is only in the heart. Appearance: Both cardiac and skeletal muscle appear striated under a microscope, while smooth muscle does not.

Answer 83

Sliding filament theory, a muscle fiber contracts when myosin filaments pull actin filaments closer together and thus shorten sarcomeres within a fiber. When all the sarcomeres in a muscle fiber shorten, the fiber contracts. Calcium released from sarcoplasmic reticulum. Calcium binds troponin; myosin binding sites exposed on actin. Myosin binds actin (cross-bridge formation). ATP hydrolysis powers the power stroke. ATP binding causes myosin release. Cycle continues until calcium is removed.

Answer 84

In embryonic development, the neural tube originates from the folding of the neural plate, a structure formed from the ectoderm, and eventually develops into the central nervous system (brain and spinal cord), while the neural crest arises from the borders of the neural plate, migrating away to form a diverse range of cell types including neurons of the peripheral nervous system, cartilage, bone, and pigment cells. Key points about their origins: Neural tube: Forms from the neural plate which is a thickened region of the ectoderm. Folds inwards to create a tube-like structure. Eventually develops into the brain and spinal cord. Neural crest: Develops at the edges of the neural plate, between the neural plate and the non-neural ectoderm. Cells "delaminate" from the neural tube and migrate extensively throughout the embryo. Differentiates into a wide variety of cell types depending on their migration pathway. Neural tube: Forms CNS (brain, spinal cord). Neural crest: Forms PNS and some CNS components.

Answer 85

**Neurons** Neurons are divided into four types: unipolar, bipolar, multipolar, and pseudounipolar. Neurons require help from glial cells to form strong connections and eliminate obsolete connections. **Glial cells** Glial cells are the most abundant cells in the central nervous system. Glial cells help maintain homeostasis and form myelin. Glial cells are classified by their morphology, location, function, and molecular composition. **Types of glial cells** **Oligodendrocytes:** Form the myelin sheath around axons in the central nervous system **Schwann cells:** Form the myelin sheath around axons in the peripheral nervous system **Astrocytes:** Provide nutrients, structural support, and maintain the extracellular environment of neurons **Microglia:** Scavenge pathogens and dead cells Ependymal cells: Produce cerebrospinal fluid that cushions neurons **Satellite cells:** Provide nutrients and structural support to neurons in the peripheral nervous system **Radial glia:** Involved in neurogenesis and neural development Neurons: Transmit signals. Glial cells: Astrocytes: Support neurons; maintain blood-brain barrier. Oligodendrocytes: Myelinate CNS axons. Microglia: Immune defense. Ependymal cells: Line ventricles; produce cerebrospinal fluid. Schwann cells: Myelinate PNS axons.

Answer 86

Soma: This is the central part of a neuron, containing the nucleus and other organelles, essentially the "brain" of the cell where most cellular processes occur. Dendrites: These are short, branching extensions that extend from the soma and receive incoming signals from other neurons, acting like the "antennae" of the neuron. Axon: A long, thin fiber that carries electrical impulses away from the cell body to other neurons, muscles, or glands. Myelin sheath: A fatty layer that wraps around the axon, acting as an insulator to speed up signal transmission by allowing for "saltatory conduction" where the signal jumps between gaps in the myelin. Nodes of Ranvier: These are the gaps in the myelin sheath where the axon membrane is exposed, allowing for the signal to be regenerated and rapidly jump along the axon. Soma: Signal integration. Dendrites: Receive signals. Axon: Conducts action potentials. Myelin sheath: Insulates axons; speeds conduction. Nodes of Ranvier: Gaps in myelin; enable saltatory conduction.

Answer 87

TLO 7.4: Myelin in CNS vs. PNS CNS: Myelinated by oligodendrocytes; limited regeneration. PNS: Myelinated by Schwann cells; better regeneration. CNS: Includes only the brain and spinal cord. PNS: Contains all nerves that extend from the brain and spinal cord to the body's extremities.

Answer 88

Topic 8: Anatomical Position, Planes, and Terminology TLO 8.1: Anatomical Position Upright, face forward, arms at sides, palms forward, feet together.

Answer 89

Standardizes descriptions. Aids in diagnosis, surgical planning, and imaging. Anatomical position Anterior: Toward the front of the body Posterior: Toward the back of the body Proximal: Close to the attachment point or trunk Distal: Away from the attachment point or trunk Superficial: Close to the surface of the skin Deep: Away from the surface of the skin Anatomical planes Coronal plane: Separates the front and back of the body Sagittal plane: Separates the left and right sides of the body Transverse plane: Separates the upper and lower halves of the body Anatomical terminology Abdominopelvic cavity: The largest cavity in the body, which contains the digestive organs, kidneys, and adrenal glands Pelvic cavity: Contains the rectum and most of the urogenital system Cranial: A term used to refer to the skull Cephalic: A term used to refer to the skull Rostral: A term used to refer to the front of the face Caudal: A term used in embryology and occasionally in human anatomy

Answer 90

Sagittal: Left/right. Coronal: Front/back. Transverse: Top/bottom.

Answer 91

TLO 8.4: Terminology Directional: Superior, inferior, anterior, posterior, medial, lateral, proximal, distal. Regional: Cephalic, thoracic, abdominal, pelvic. Cavities: Dorsal (brain/spinal cord), ventral (thoracic, abdominopelvic). Movements: Flexion, extension, abduction, adduction, rotation, pronation, supination. Directional terms Superior: Toward the head, or upper Inferior: Away from the head, or lower Anterior: Front Posterior: Back Medial: Toward the midline of the body Lateral: Away from the midline of the body Proximal: Closer to the trunk or point of attachment Distal: Farther from the trunk or point of attachment Superficial: Closer to the surface of the body Deep: Farther from the surface of the body Regional terms The abdominopelvic cavity can be divided into regions or quadrants to describe the location of pain or masses Cavities Dorsal cavity The cavity in the back of the body that contains the cranial and vertebral cavities Ventral cavity The cavity in the front of the body that contains the thoracic and abdominopelvic cavities Thoracic cavity The cavity within the rib cage that contains the heart and lungs Abdominopelvic cavity The largest cavity in the body that contains the digestive and reproductive organs

Answer 92

The central dogma is summarized as: DNA → RNA → Protein.

Answer 93

DNA is duplicated to ensure genetic material is inherited by daughter cells during cell division.

Answer 94

DNA is transcribed into RNA (specifically, mRNA) by RNA polymerase.

Answer 95

Promoters: Regions of DNA that signal RNA polymerase to start transcription. Exons and introns: Exons are coding regions of mRNA; introns are spliced out.

Answer 96

mRNA is translated into proteins at the ribosome.

Answer 97

tRNA: Delivers amino acids. Ribosomes: Facilitate peptide bond formation between amino acids. Codons: Groups of three nucleotides in mRNA that encode specific amino acids.

Answer 98

A set of rules dictating how nucleotide sequences in mRNA are translated into proteins.

Answer 99

Triplet nucleotide sequences (e.g., AUG) that code for amino acids or regulatory signals.

Answer 100

* Start codon: AUG (methionine) initiates protein translation. * Stop codons: UAA, UAG, UGA terminate translation.

Answer 101

TLO 1.2: Describe the genetic code and codons Key Features: * Universal: Shared by almost all organisms. * Degenerate: Multiple codons can encode the same amino acid (e.g., UUU and UUC both encode phenylalanine). * Non-overlapping: Each nucleotide is part of only one codon. The genetic code is universal because all species use the same four bases A,T,C and G, and each base sequence codes for the same amino acid in all species. despite the 64 possible codons (sequence of three bases), there are only 20 possible amino acids. This means that multiple codons code for one amino acid, meaning the code is degenerate. Overlapping refers to how the code is read. The first three bases are read as one codon, then the next three as the second etc, therefore each base is read only once and the bases do not overlap.

Answer 102

TLO 1.3: Define mutations and differentiate between point vs. frameshift mutations Mutation: A permanent change in the DNA sequence that can affect protein function.

Answer 103

TLO 1.3: Define mutations and differentiate between point vs. frameshift mutations Point mutations: A single nucleotide substitution.

Answer 104

TLO 1.3: Define mutations and differentiate between point vs. frameshift mutations Silent mutation: No change in the encoded amino acid (e.g., CUU → CUC, both encode leucine).

Answer 105

TLO 1.3: Define mutations and differentiate between point vs. frameshift mutations Missense mutation: Changes the amino acid (e.g., Glu → Val in sickle cell anemia). A missense mutation is a DNA change that results in different amino acids being encoded at a particular position in the resulting protein. Some missense mutations alter the function of the resulting protein.

Answer 106

TLO 1.3: Define mutations and differentiate between point vs. frameshift mutations Nonsense mutation: Converts a codon into a stop codon (e.g., UGC → UGA).

Answer 107

TLO 1.3: Define mutations and differentiate between point vs. frameshift mutations Frameshift mutations: Caused by insertion or deletion of nucleotides not in multiples of three, disrupting the reading frame. Example: Adding one nucleotide to AUG-CUU becomes AUC-UUC, altering all downstream amino acids.

Answer 108

TLO 1.4: Describe trinucleotide repeat disorders Disorders caused by the abnormal expansion of three-nucleotide sequences within or near genes. Normal individuals have stable numbers of repeats, but expanded repeats cause disease. Examples: Huntington’s disease: CAG repeats in the HTT gene cause toxic proteins. Fragile X syndrome: CGG repeats in the FMR1 gene lead to gene silencing. Myotonic dystrophy: CTG repeats in the DMPK gene interfere with protein interactions.

Answer 109

A phenomenon where a genetic disorder worsens or manifests earlier in subsequent generations due to repeat expansions. Examples: Huntington’s disease: Earlier onset with paternal inheritance. Myotonic dystrophy: Severity increases with maternal transmission.

Answer 110

Topic 2: Single Gene Disorders Gene: A DNA sequence encoding a protein or functional RNA.

Answer 111

Topic 2: Single Gene Disorders Locus: A gene's location on a chromosome.

Answer 112

Topic 2: Single Gene Disorders Allele: Variant forms of a gene.

Answer 113

Topic 2: Single Gene Disorders Genotype: The genetic makeup of an individual.

Answer 114

Topic 2: Single Gene Disorders Phenotype: Observable traits resulting from genotype-environment interactions.

Answer 115

Topic 2: Single Gene Disorders Homozygous: Possessing two identical alleles (e.g., AA or aa).

Answer 116

Topic 2: Single Gene Disorders Heterozygous: Possessing two different alleles (e.g., Aa).

Answer 117

Topic 2: Single Gene Disorders Dominant: A trait expressed with one allele (e.g., Aa or AA).

Answer 118

Topic 2: Single Gene Disorders Recessive: A trait expressed only with two identical alleles (e.g., aa).

Answer 119

TLO 2.2: Autosomal dominant inheritance vs. autosomal recessive inheritance Autosomal dominant: Requires only one mutated allele for the phenotype. Examples: Marfan syndrome, Huntington’s disease. Recurrence risk: 50% if one parent is affected.

Answer 120

TLO 2.2: Autosomal dominant inheritance vs. autosomal recessive inheritance Autosomal recessive: Requires two mutated alleles for the phenotype. Examples: Cystic fibrosis, sickle cell anemia. Recurrence risk: 25% if both parents are carriers.

Answer 121

TLO 2.3: X-linked inheritance X-linked dominant: Affects males and females. Examples: Rett syndrome, hypophosphatemic rickets.

Answer 122

TLO 2.3: X-linked inheritance X-linked recessive: Affects males more severely; females are carriers. Examples: Hemophilia A, Duchenne muscular dystrophy. Recurrence risk: Sons of carrier mothers have a 50% chance of being affected.

Answer 123

TLO 2.4: Properties of mitochondrial inheritance Inherited exclusively from the mother. Affects tissues requiring high energy (e.g., brain, muscles). Examples: Leber hereditary optic neuropathy (LHON), MELAS syndrome.

Answer 124

TLO 2.5: Define incomplete penetrance and pleiotropy Incomplete penetrance: Not all individuals with a mutation exhibit symptoms (e.g., BRCA1 mutation carriers). Pleiotropy: A single gene mutation impacts multiple systems (e.g., Marfan syndrome affects connective tissue, heart, and eyes).

Answer 125

TLO 2.6: Describe genetic imprinting and uniparental disomy Genetic imprinting: Differential expression of genes depending on their parental origin. Uniparental disomy: Both chromosomes come from one parent. Examples: Prader-Willi syndrome: Paternal deletion on chromosome 15 or maternal uniparental disomy. Angelman syndrome: Maternal deletion on chromosome 15 or paternal uniparental disomy.

Answer 126

Genotype frequency refers to the proportion of individuals in a population with a specific genotype (e.g., homozygous dominant, heterozygous, or homozygous recessive). It is expressed as a fraction or percentage of the total population. Mathematically: f(Genotype)=Number of individuals with a specific genotypeTotal number of individuals in the populationf(Genotype)=Total number of individuals in the populationNumber of individuals with a specific genotype

Answer 127

Allele Frequency Allele frequency is the proportion of a specific allele (e.g., dominant or recessive) among all alleles at a particular locus in the population. Allele frequency is important because it measures genetic diversity within a population. For a population with two alleles (A and a): f(A)=2(AA)+(Aa)2N,f(a)=2(aa)+(Aa)2Nf(A)=2N2(AA)+(Aa),f(a)=2N2(aa)+(Aa) Where: * NN is the total number of individuals in the population.

Answer 128

Suppose a population consists of 100 individuals with the following genotypes: 25 AAAA, 50 AaAa, and 25 aaaa. Genotype frequencies: f(AA)=25100=0.25,f(Aa)=50100=0.50,f(aa)=25100=0.25f(AA)=10025=0.25,f(Aa)=10050=0.50,f(aa)=10025=0.25 Allele frequencies: f(A)=2(25)+50200=0.5,f(a)=2(25)+50200=0.5f(A)=2002(25)+50=0.5,f(a)=2002(25)+50=0.5

Answer 129

The Hardy-Weinberg equilibrium describes a theoretical state in which the allele and genotype frequencies in a population remain constant from generation to generation, provided certain assumptions are met.

Answer 130

Key Assumptions of HWE: 1. Large population size: Prevents genetic drift. 2. No mutation: No new alleles are introduced or altered. 3. Random mating: No preference for specific genotypes in mating. 4. No natural selection: All genotypes have equal reproductive success. 5. No gene flow: No migration into or out of the population.

Answer 131

Implications: The Hardy-Weinberg principle provides a baseline for measuring genetic variation and helps identify when evolutionary forces are acting on a population. If the observed genotype frequencies deviate from expected frequencies under HWE, one or more of the assumptions may be violated, indicating evolutionary change. Mathematically, the equilibrium condition for a single gene with two alleles (A and a) is: p2+2pq+q2=1p2+2pq+q2=1 Where: * pp is the frequency of allele AA, and qq is the frequency of allele aa. * p2p2: Frequency of homozygous dominant genotype (AAAA). * 2pq2pq: Frequency of heterozygous genotype (AaAa). * q2q2: Frequency of homozygous recessive genotype (aaaa).

Answer 132

Given allele frequencies (pp and qq), genotype frequencies can be estimated using the HWE equation. Example: In a population, the frequency of allele AA (pp) is 0.6, and the frequency of allele aa (qq) is 0.4 (p+q=1p+q=1). Homozygous dominant (AAAA): f(AA)=p2=(0.6)2=0.36f(AA)=p2=(0.6)2=0.36 Heterozygous (AaAa): f(Aa)=2pq=2(0.6)(0.4)=0.48f(Aa)=2pq=2(0.6)(0.4)=0.48 Homozygous recessive (aaaa): f(aa)=q2=(0.4)2=0.16f(aa)=q2=(0.4)2=0.16 These frequencies can be compared to observed data to determine if the population is in HWE.

Answer 133

TLO 3.4: Describe the Factors Responsible for Genetic Variation in Populations Mutation Spontaneous changes in the DNA sequence introduce new alleles. Mutations are the ultimate source of all genetic variation and are critical for evolution.

Answer 134

TLO 3.4: Describe the Factors Responsible for Genetic Variation in Populations Genetic Variation refers to the diversity of alleles and genotypes within a population. Several factors contribute to genetic variation: Genetic Recombination During meiosis, homologous chromosomes exchange genetic material (crossing over), creating new allele combinations.

Answer 135

TLO 3.4: Describe the Factors Responsible for Genetic Variation in Populations Genetic Variation refers to the diversity of alleles and genotypes within a population. Several factors contribute to genetic variation: Gene Flow (Migration) Movement of individuals or gametes between populations introduces new alleles, increasing genetic diversity.

Answer 136

TLO 3.4: Describe the Factors Responsible for Genetic Variation in Populations Genetic Variation refers to the diversity of alleles and genotypes within a population. Several factors contribute to genetic variation: Genetic Drift Random changes in allele frequencies, especially in small populations, can lead to loss of genetic variation.

Answer 137

TLO 3.4: Describe the Factors Responsible for Genetic Variation in Populations Genetic Variation refers to the diversity of alleles and genotypes within a population. Several factors contribute to genetic variation: Natural Selection Differential survival and reproduction of individuals with specific genotypes can increase or decrease genetic variation, depending on selective pressures.

Answer 138

TLO 3.4: Describe the Factors Responsible for Genetic Variation in Populations Genetic Variation refers to the diversity of alleles and genotypes within a population. Several factors contribute to genetic variation: Non-Random Mating Assortative mating or inbreeding affects genotype frequencies and reduces heterozygosity.

Answer 139

TLO 3.4: Describe the Factors Responsible for Genetic Variation in Populations Genetic Variation refers to the diversity of alleles and genotypes within a population. Several factors contribute to genetic variation: Population Size Larger populations tend to maintain more genetic variation due to reduced effects of genetic drift.

Answer 140

TLO 3.4: Describe the Factors Responsible for Genetic Variation in Populations Genetic Variation refers to the diversity of alleles and genotypes within a population. Several factors contribute to genetic variation: Environmental Factors Selective pressures, such as climate, predators, or food availability, influence which genotypes are advantageous.

Answer 141

Topic 4: Cytogenetics (Chromosomal Abnormalities) TLO 4.1: Demonstrate understanding of karyotypes and chromosome nomenclature Karyotype: A display of an individual’s complete set of chromosomes arranged in pairs and sorted by size, centromere position, and banding pattern. Chromosomes are visualized using stains (e.g., Giemsa stain for G-banding). A normal karyotype includes 22 pairs of autosomes and 1 pair of sex chromosomes.

Answer 142

Topic 4: Cytogenetics (Chromosomal Abnormalities) TLO 4.1: Demonstrate understanding of karyotypes and chromosome nomenclature Chromosome nomenclature: The total chromosome number, sex chromosomes, and any abnormalities are noted. Example: 46,XX: Normal female. 47,XX,+21: Female with trisomy 21 (Down syndrome). 46,XY,t(9;22): Male with translocation between chromosomes 9 and 22 (Philadelphia chromosome, associated with chronic myeloid leukemia).

Answer 143

TLO 4.2: Discuss numerical chromosomal abnormalities Numerical abnormalities: Variations in chromosome number due to errors in cell division (nondisjunction or anaphase lag). Euploidy: A normal set of chromosomes (e.g., 46 in humans). Aneuploidy: Gain or loss of chromosomes.

Answer 144

TLO 4.2: Discuss numerical chromosomal abnormalities Examples of autosomal aneuploidies: Trisomy 21 (Down syndrome): * Three copies of chromosome 21. * Clinical features: Intellectual disability, hypotonia, characteristic facial features, congenital heart defects. Trisomy 18 (Edwards syndrome): * Three copies of chromosome 18. * Clinical features: Severe developmental delays, overlapping fingers, rocker-bottom feet. Trisomy 13 (Patau syndrome): * Three copies of chromosome 13. * Clinical features: Microcephaly, cleft lip/palate, polydactyly, congenital heart defects.

Answer 145

TLO 4.2: Discuss numerical chromosomal abnormalities Examples of sex chromosome aneuploidies: Turner syndrome (45,X): Monosomy of the X chromosome in females. Clinical features: Short stature, gonadal dysgenesis, webbed neck.

Answer 146

TLO 4.2: Discuss numerical chromosomal abnormalities Examples of sex chromosome aneuploidies: Klinefelter syndrome (47,XXY): Extra X chromosome in males. Clinical features: Tall stature, hypogonadism, gynecomastia, infertility.

Answer 147

TLO 4.3: Describe the most common cause of numerical chromosomal abnormalities Cause: Most numerical abnormalities result from nondisjunction during meiosis. Nondisjunction: Failure of homologous chromosomes (meiosis I) or sister chromatids (meiosis II) to separate. This results in gametes with an extra or missing chromosome, leading to aneuploidy after fertilization.

Answer 148

TLO 4.4: Describe structural chromosomal abnormalities Structural abnormalities: Result from chromosomal breakage and improper repair. Translocation: Exchange of segments between non-homologous chromosomes. Robertsonian translocation: Fusion of two acrocentric chromosomes (e.g., t(14;21) associated with hereditary Down syndrome). Deletion: Loss of a chromosome segment. Example: Cri-du-chat syndrome (5p deletion). Inversion: A chromosome segment is reversed end-to-end. Paracentric inversion: Does not involve the centromere. Pericentric inversion: Includes the centromere. Ring chromosome: A circular chromosome formed when the ends fuse after breakage. Example: Turner syndrome (ring X chromosome).

Answer 149

Topic 5: Genetics of Common Diseases TLO 5.1: Discuss multifactorial inheritance and its influential factors Multifactorial inheritance: Results from the combined effect of multiple genes (polygenic) and environmental factors. Examples of multifactorial diseases: Type 2 diabetes: Influenced by genetic predisposition and lifestyle factors (e.g., obesity, diet). Hypertension: Genetic susceptibility combined with environmental triggers (e.g., salt intake, stress). Congenital diseases: Cleft lip/palate, neural tube defects (e.g., spina bifida).

Answer 150

TLO 5.2: Describe the multifactorial threshold model Threshold model: Explains the likelihood of developing a multifactorial disease. Disease occurs when the combined genetic and environmental factors surpass a certain threshold. The threshold varies between sexes and populations. Example: Pyloric stenosis occurs more frequently in males, indicating a lower threshold for expression.

Answer 151

TLO 5.3: Discuss the assessment of recurrence risk for multifactorial diseases Recurrence risk depends on: Number of affected relatives. Severity of the condition in the proband. Closeness of the familial relationship. Population prevalence. Example: Risk of neural tube defects decreases with folic acid supplementation but increases with maternal history of the defect.

Answer 152

Topic 6: Genetic Analysis TLO 6.1: Describe genetic analysis and different methods used Genetic analysis involves studying DNA, RNA, and protein to identify mutations and chromosomal abnormalities. Cytogenetic techniques: Karyotyping, fluorescence in situ hybridization (FISH). Molecular techniques: PCR, next-generation sequencing (NGS), microarrays. Biochemical analysis: Enzyme assays to detect metabolic abnormalities.

Answer 153

TLO 6.2: Describe different blotting techniques and their implications in diagnosis Southern blot: Detects specific DNA sequences. Used for large gene rearrangements (e.g., Duchenne muscular dystrophy). Northern blot: Analyzes RNA to study gene expression. Example: Detection of gene silencing in Fragile X syndrome. Western blot: Detects specific proteins. Example: Diagnosing HIV through detection of viral proteins.

Answer 154

TLO 6.3: Describe the polymerase chain reaction (PCR) and its use in genetic analysis PCR amplifies specific DNA sequences using primers and a thermostable DNA polymerase (e.g., Taq polymerase). Steps: Denaturation: DNA strands separate at high temperature. Annealing: Primers bind complementary sequences. Extension: DNA polymerase synthesizes the target sequence. Applications: Detecting mutations (e.g., BRCA1/2 mutations in breast cancer). Pathogen detection (e.g., HIV, SARS-CoV-2).

Answer 155

TLO 6.4: Discuss different genetic diseases routinely screened in fetuses and newborns Prenatal screening: Non-invasive tests: Ultrasound for structural abnormalities. Cell-free DNA (cfDNA) for detecting trisomies (e.g., trisomy 21, 18, 13). Invasive tests: Amniocentesis: Analyzes fetal karyotype. Chorionic villus sampling (CVS): Detects genetic disorders.

Answer 156

a.Phenylalanine b.Proline c.Arginine **d.Valine** e.Lysine Sickle cell anemia is a condition due to missense mutation where Glutamic acid is replaced by Valine.Hydrophilic amino acid is replaced by hydrophobic amino acid in the outer surface of protein resultingin abnormal hemoglobin. It is an autosomal recessive disease caused by a point mutation in thehemoglobin beta gene (HBB) found on chromosome 11p15.5. Carrier frequency of HBB variessignificantly around the world, with high rates associated with zones of high malaria incidence, sincecarriers are somewhat protected against malaria. About 8% of the African American population arecarriers. A mutation in HBB results in the production of a structurally abnormal hemoglobin (Hb), calledHbS. Hb is an oxygen carrying protein that gives red blood cells (RBC) their characteristic color. Undercertain conditions, like low oxygen levels or high hemoglobin concentrations, in individuals who arehomozygous for HbS, the abnormal HbS clusters together, distorting the RBCs into sickled shapes.These deformed and rigid RBCs become trapped within small blood vessels and block them, producingpain and eventually damaging organs. The correct answer is: Valine

Answer 157

a.0%; 100% **b.50%; 50% ** c.100%; 0% d.0%; 50% e.2/3; 1/3 Because the man transmits his X chromosome to all of his daughters, all of the daughters must carry atleast one copy of the mutation. The mother will transmit a mutation-carrying X chromosome half thetime and a normal X chromosome half the time. Thus, half of the daughters will be heterozygouscarriers, and half will be affected homozygotes, having received a mutation from both parents. The correct answer is: 50%; 50%

Answer 158

**a.0%** b.100% c.50% d.25%

Answer 159

a.Acceptation b.Mutation **c.Anticipation ** d.Assumption

Answer 160

a.25% b.75% **c.0%** d.100% e.50% In these situations, try to identify the pattern of inheritance first. The pattern shown here is autosomalrecessive because we can see that in generation I, the male parent is affected, whereas the femaleparent is normal. In the progeny, the sons and daughters are affected with an approximately equalfrequency. This shows it to be an autosomal trait. It is not an X-linked trait, because the father contributes the X chromosome only to the daughter, not tothe son. Similarly, the Y chromosome is passed down to the son, not the daughter. Since the affectedfather has affected both the son and daughter, it is not a sex-linked trait, rather it is an autosomal trait. Had it been a dominant trait, all the progeny would have been affected. Here we can see that ingeneration II, a son is normal. Also, in the next generation we can see the trait skipping a generation.This happens in case of a recessive trait. Recessive traits require two identical alleles for their expression.An affected child can have unaffected parents. Hence, we can conclude that the given pedigree represents the transmission of an autosomal recessivetrait. Now draw the punnett square based on what the question is asking. Here the male is affected so in AR for them to be affected they should be homozygous for the disease;you can give any nomenclature to the allele but remember what nomenclature or color you are givinghere I will give ‘a’ for affected and ‘A’ for unaffected allele. So, the male’s genotype is aa. Now for thefemale it says homozygous and normal so her genotype is AA. If the question had said heterozygousnormal/carrier then it would have been Aa. But let’s go back to our scenario and draw a Punnett square. a (male) a (male) A (female) Aa Aa A (female) Aa Aa As it is AR we need both affected allele’s to be inherited for the disease to be phenotypically visible orfor the individual to be affected. Hence the affected individual recurrence risk ratio is 0/4= 0% But the risk of the child being a carrier for the disease is 4/4= 100% Answer: (0%)

Answer 161

**a.X-linked recessive** b.X-linked dominant c.Autosomal dominant d.Mitochondrial e.Autosomal recessive The pedigree shows that only males are affected by the drug intolerance. Specifically, male offspring ofunaffected parents are affected. There is no evidence of male-to-male transmission. This pattern is mostconsistent with X-linked recessive inheritance from an asymptomatic carrier female in the firstgeneration. In X-linked recessive inheritance: 1. Affected males will always produce unaffected sons and carrier daughters. 2. Carrier females have a 50% chance of producing an affected son or carrier daughter. G6PD deficiency,which causes acute hemolytic anemia on exposure to oxidant drugs, follows an X-linked recessivepattern of inheritance. The correct answer is: X-linked recessive

Answer 162

a.The phenomenon is due to incomplete penetrance b.Autosomal dominant **c.Mitochondrial** d.The phenomenon is due to imprinting e.Autosomal recessive The correct answer is: Mitochondrial

Answer 163

a.Silent mutation b.Nonsense mutation **c.Trinucleotide repeat** d.Missense mutation e.Chromosomal deletion HD is an autosomal dominant disease caused by degeneration of striatal neurons and characterized bya progressive movement disorder and dementia. Jerky, hyperkinetic, sometimes dystonic movementsinvolving all parts of the body (chorea) are characteristic; affected individuals may later developbradykinesia and rigidity. The disease is relentlessly progressive and uniformly fatal, with an averagecourse of about 15 years. The gene for HD, HTT, located on chromosome 4p16.3, encodes a 348-kDprotein known as huntingtin. In the first exon of the gene, there is a stretch of CAG repeats that encodesa polyglutamine region near the N terminus of the protein. Normal HTT genes contain 6 to 35 copies ofthe repeat; when the number of repeats is increased beyond this level, it is associated with disease. The correct answer is: Trinucleotide repeat

Answer 164

a.Northern blot b.Southern blot c.Dot blot d.Western blot **e.Polymerase chain reaction (PCR)** PCR provides a means of amplifying distinct DNA sequences, starting with incredibly tiny amounts ofDNA and resulting in large amounts of identical copies sufficient for analysis. PCR is sensitive enough toamplify the DNA from a single cell to yield amounts sufficient for analysis. PCR requires prior knowledgeof sequence information at the two ends of the target sequence. PCR needs primers to start DNAsynthesis, which means that some DNA sequence in or close to the region of interest must be known. The correct answer is: Polymerase chain reaction (PCR)

Answer 165

**a.Electrophoresis** b.Autoradiography c.Hybridization d.Addition of primer e.Probing

Answer 166

a.protein-->RNA-->DNA **b.DNA-->mRNA-->protein** c.RNA-->DNA-->protein d.mRNA-->DNA-->protein e.DNA-->protein-->mRNA

Answer 167

a.2/3,000 b.1/9,000 c.1/6,000 d.(1/3,000)2 e.1/3,000 Because males have only a single X chromosome, each affected male has one copy of the disease-causing recessive mutation. Thus, the incidence of an X-linked recessive disease in the male portion of a population is a direct estimate of the gene frequency in the population. The correct answer is: 1/3,000

Answer 168

**a.Trisomy 21** b.Neural tube defects c.Turner syndrome d.Omphalocele e.Fetal alcohol syndrome The correct answer is: Trisomy 21

Answer 169

a.Polyploidy b.Variable penetrance c.Segregation d.Imprinting **e.Pleiotropy** Cystathionine beta-synthase deficiency is the enzyme defect present in classic homocystinuria.Homocystinuria is characterized clinically by ectopia lentis, mental retardation, marfanoid habitus andosteoporosis in addition to vascular problems. Pleiotropy is the occurrence of multiple phenotypicmanifestations, often in different organ systems, as a result of a single genetic defect. Pleiotropydescribes instances where multiple phenotypic manifestations result from a single genetic mutation.Most syndromic genetic illnesses exhibit pleiotropy. Polyploidy occurs when more than two completesets of homologous chromosomes exist within an organism or partial hydatidiform mole, for example,there are cells of nonstandard ploidy (typically 69XXX, 69XXY or 69 XYY). The chromosomes in this caseare derived from one haploid maternal set and two haploid paternal sets of chromosomes. Penetrancerefers to the proportion of individuals with a given genotype that express the associated phenotype. Inincomplete penetrance, less than 100% of individuals with a given genotype express its associatedphenotype. The law of segregation (Mendel's first law) describes the phenomenon wherebygametogenesis within the parent organism results in the separation of paired chromosomes and thusthe separation of paired 31 genes so that each offspring inherits only half of each parent's geneticcomposition Parental imprinting refers to the preferential transcription of genes from one or another ofa homologous pair of chromosomes depending on the parental origin of the chromosome. The correct answer is: Pleiotropy

Answer 170

a.Mitochondrial inheritance b.X-linked recessive inheritance c.Sex-dependent penetrance **d.Imprinting** e.X-linked dominant inheritance Imprinting refers to the differential transcriptional activity of genes inherited from the father versus themother. Under mitochondrial inheritance, only an affected mother can transmit the disease phenotype;the offspring of affected males are always unaffected. The other modes of inheritance can influence therelative proportions of affected individuals who belong to one gender or the other (e.g., more affectedmales under X-linked recessive inheritance, more affected females under X-linked dominantinheritance), but they do not involve any differences in expression depending on the transmittingparent. The correct answer is: Imprinting

Answer 171

**a.cfDNA of the fetus** b.Maternal DNA c.The presence of neural tube defect d.Amniotic fluid e.The gestational age Non-invasive prenatal screening (NIPS), used for common autosomal and sex chromosomeaneuploidies possible, with sensitivities and specificities approaching 99% for trisomy 21. After 9-10weeks post LMP, the serum of a pregnant woman contains fetal DNA that is not contained in thenucleus of a cell but is floating freely in the maternal circulation. Significant proportion (5 - 50 %) of allcfDNA found in maternal plasma. Short pieces of DNA. Commercial kits and PCR to isolate and prepareDNA for analysis. The correct answer is: cfDNA of the fetus

Answer 172

a.Male are more frequently affected than females b.Females are more frequently affected than males **c.Affected individuals are not seen in every generation** d.Clinical expression results from heterozygous allele inheritance The correct answer is: Affected individuals are not seen in every generation

Answer 173

Controls cellular activities and houses genetic material.

Answer 174

Produce energy through ATP synthesis

Answer 175

Rough ER synthesizes proteins; smooth ER synthesizes lipids.

Answer 176

Modifies, packages, and distributes cellular products.

Answer 177

Contain digestive enzymes for breaking down cellular waste.

Answer 178

Involved in oxidation reactions, particularly fatty acid breakdown.

Answer 179

Site of protein synthesis.

Answer 180

Storage organelles for various substances.

Answer 181

Responsible for photosynthesis.

Answer 182

Controls what enters and exits the cell.

Answer 183

Forms the membrane's basic structure.

Answer 184

Allows lateral movement of membrane components.

Answer 185

Perform various functions (e.g., transport, signaling).

Answer 186

Regulates membrane fluidity and stability.

Answer 187

Form the glycocalyx for cell recognition.

Answer 188

This structure enables selective permeability, cell signaling, and maintenance of cell shape.

Answer 189

Sourced from dietary amino acids.

Answer 190

Sourced from dietary fatty acids and glycerol.

Answer 191

Sourced from dietary simple sugars.

Answer 192

Sourced from nucleotides synthesized in the body or from diet.

Answer 193

1. Structural components (e.g., collagen) 2. Enzymes catalyzing biochemical reactions 3. Transport molecules (e.g., hemoglobin) 4. Hormones (e.g., insulin) 5. Antibodies for immune function 6. Cell signaling receptors 7. Muscle contraction components (actin and myosin)

Answer 194

1. Energy storage (triglycerides) 2. Cell membrane components (phospholipids and cholesterol) 3. Insulation (subcutaneous fat) 4. Hormone precursors (steroid hormones) 5. Facilitators of fat-soluble vitamin absorption 6. Cell signaling molecules (lipid-based second messengers)

Answer 195

1. Primary energy source (glucose) 2. Energy storage (glycogen) 3. Structural components (e.g., ribose in nucleic acids) 4. Cell recognition molecules (glycoproteins and glycolipids) 5. Dietary fiber for digestion and gut health

Answer 196

1. Genetic information storage (DNA) 2. Protein synthesis (mRNA, tRNA, rRNA) 3. Gene regulation (miRNA and other regulatory RNAs) 4. Enzyme cofactors (e.g., NAD+ and FAD in metabolism)

Answer 197

Misfolding (e.g., Alzheimer's) or enzyme deficiencies (e.g., Phenylketonuria)

Answer 198

Impaired glucose metabolism (diabetes) or glycogen storage diseases

Answer 199

Cholesterol imbalance (atherosclerosis) or lipid storage disorders (e.g., Tay-Sachs)

Answer 200

Genetic mutations (e.g., sickle cell anemia) or DNA repair defects (increased cancer risk)

Answer 201

Simple diffusion, facilitated diffusion, osmosis

Answer 202

Primary active transport, secondary active transport

Answer 203

Endocytosis, exocytosis

Answer 204

* Concentration gradient * Molecule size and polarity * Membrane permeability * Energy requirements * Presence of specific transport proteins

Answer 205

* Molecules move directly through the phospholipid bilayer * No energy required * Limited to small, nonpolar molecules

Answer 206

* Requires transport proteins (channels or carriers) * No energy required * Allows passage of larger or polar molecules * Can be regulated by the cell

Answer 207

* Uses energy from electrochemical gradient created by primary active transport * Example: Glucose-sodium cotransporter (SGLT) in kidney tubules (glucose reabsorption)

Answer 208

* Directly uses ATP for energy * Example: Na+/K+ ATPase pump in neurons (maintains resting membrane potential)

Answer 209

* G1: Cell growth and preparation for DNA synthesis * S: DNA replication * G2: Preparation for mitosis

Answer 210

* Mitosis: Nuclear division * Cytokinesis: Cytoplasmic division

Answer 211

Quiescent or senescent state (optional)

Answer 212

Chromatin condenses, nuclear envelope breaks down, spindle fibers form

Answer 213

Chromosomes align at the metaphase plate

Answer 214

Sister chromatids separate and move to opposite poles

Answer 215

Chromosomes decondense, nuclear envelopes reform, cytokinesis begins

Answer 216

Can form all cell types (e.g., zygote)

Answer 217

Can form most cell types (e.g., embryonic stem cells)

Answer 218

Can form multiple cell types within a lineage (e.g., hematopoietic stem cells)

Answer 219

Can form only one cell type (e.g., spermatogonial stem cells)

Answer 220

Regenerative medicine, tissue engineering, disease modeling, drug screening.

Answer 221

* Tissue homeostasis * Proper organ function * Prevention of cancer and other diseases * Embryonic development * Immune system regulation

Answer 222

Homologous chromosomes pair, crossover, and separate

Answer 223

Sister chromatids separate

Answer 224

Results in four haploid gametes with genetic diversity.

Answer 225

* Both involve DNA replication and cell division

Answer 226

* Meiosis produces haploid gametes; mitosis produces identical diploid cells * Meiosis involves two rounds of division; mitosis involves one * Meiosis includes genetic recombination; mitosis does not * Meiosis occurs only in germ cells; mitosis occurs in somatic cells

Answer 227

23 pairs of chromosomes

Answer 228

Circular DNA in mitochondria

Answer 229

Protein-coding sequences

Answer 230

Promoters, enhancers, silencers

Answer 231

Introns, repetitive sequences

Answer 232

Protective end sequences of chromosomes

Answer 233

Unwinds the DNA double helix

Answer 234

Synthesizes RNA primers

Answer 235

Main replicative enzyme, extends DNA strands

Answer 236

Removes RNA primers, fills gaps

Answer 237

Joins Okazaki fragments

Answer 238

* Eukaryotic replication is slower and more complex * Eukaryotes have multiple origins of replication; prokaryotes have one * Eukaryotes replicate linear chromosomes; prokaryotes replicate circular DNA * Eukaryotes have telomere maintenance; prokaryotes do not

Answer 239

* Both use semiconservative replication * Both require similar enzymes (helicases, polymerases, ligases)

Answer 240

1. Initiation: RNA polymerase binds to promoter 2. Elongation: RNA synthesis 3. Termination: RNA release 4. Post-transcriptional modifications: 5' capping, 3' polyadenylation, splicing

Answer 241

1. Initiation: Ribosome assembly on mRNA 2. Elongation: Amino acid chain formation 3. Termination: Release of completed protein 4. Post-translational modifications: Folding, chemical modifications

Answer 242

1. G protein-coupled receptors (GPCRs) 2. Receptor tyrosine kinases (RTKs) 3. Ion channel-linked receptors 4. Enzyme-linked receptors

Answer 243

1. G protein-coupled receptors (GPCRs): Signal transduction through G proteins 2. Receptor tyrosine kinases (RTKs): Phosphorylation of target proteins 3. Ion channel-linked receptors: Direct ion flow across membranes 4. Enzyme-linked receptors: Catalyze intracellular reactions

Answer 244

1. Receptors: Detect and respond to signals 2. Signal transducers: Relay and amplify signals 3. Enzymes: Modify other proteins 4. Scaffold proteins: Organize signaling complexes 5. Transcription factors: Regulate gene expression 6. Ion channels: Control ion flow and membrane potential

Answer 245

Endocrine signaling: Long-distance communication via bloodstream Paracrine signaling: Short-distance communication between nearby cells Autocrine signaling: Cell signals to itself. Transduction pathways: 1. cAMP pathway 2. Phosphoinositide pathway 3. JAK-STAT pathway 4. MAP kinase pathway Each signaling mechanism can activate various transduction pathways depending on the specific receptor and ligand involved.

Answer 246

1. Lower activation energy of reactions 2. Exhibit substrate specificity 3. Remain unchanged after catalysis 4. Function optimally under specific conditions (pH, temperature) 5. Can be regulated by various factors

Answer 247

1. Michaelis-Menten kinetics 2. Km (Michaelis constant) and Vmax (maximum velocity) 3. Lineweaver-Burk plot for determining kinetic parameters 4. Effects of substrate concentration on reaction rate 5. Enzyme saturation

Answer 248

1. Oxidoreductases: Catalyze oxidation-reduction reactions 2. Transferases: Transfer functional groups between molecules 3. Hydrolases: Catalyze hydrolysis reactions 4. Lyases: Add or remove groups without hydrolysis 5. Isomerases: Catalyze intramolecular rearrangements 6. Ligases: Join two molecules using ATP hydrolysis

Answer 249

1. Competitive inhibitors: Compete with substrate for active site (e.g., statins inhibiting HMG-CoA reductase) 2. Non-competitive inhibitors: Bind to allosteric site (e.g., aspirin inhibiting cyclooxygenase) 3. Irreversible inhibitors: Permanently modify enzyme (e.g., penicillin inhibiting bacterial cell wall synthesis) 4. Suicide inhibitors: Enzyme converts inhibitor to reactive form (e.g., acyclovir inhibiting viral DNA polymerase)

Answer 250

Glucose is the primary energy source because: 1. It's readily available from carbohydrate digestion 2. It can be quickly metabolized for energy 3. All cells can use it 4. It can be stored as glycogen for later use 5. It's essential for brain function

Answer 251

1. Cytoplasm: Glycolysis 2. Mitochondrial matrix: Krebs cycle, fatty acid oxidation 3. Inner mitochondrial membrane: Electron transport chain, oxidative phosphorylation 4. Endoplasmic reticulum: Lipid synthesis 5. Peroxisomes: Fatty acid oxidation (very long-chain fatty acids)

Answer 252

Aerobic metabolism: Requires oxygen for complete oxidation of substrates Example: Complete glucose oxidation through glycolysis, Krebs cycle, and electron transport chain. Anaerobic metabolism: Occurs without oxygen Example: Lactic acid fermentation during intense exercise

Answer 253

Glycolysis: 1. Glucose → 2 Pyruvate 2. Net production: 2 ATP, 2 NADH Krebs cycle: 1. Acetyl-CoA → 2 CO2 2. Per cycle: 3 NADH, 1 FADH2, 1 GTP Electron Transport Chain: 1. NADH and FADH2

Answer 254

1. Glycogen synthase: Adds glucose units to glycogen 2. Glycogen phosphorylase: Breaks down glycogen to glucose-1-phosphate 3. Branching enzyme: Creates branch points in glycogen 4. Debranching enzyme: Removes branch points during glycogen breakdown Steps: 1. Glycogenesis: Glucose → Glucose-6-phosphate → Glucose-1-phosphate → UDP-glucose → Glycogen 2. Glycogenolysis: Glycogen → Glucose-1-phosphate → Glucose-6-phosphate → Glucose (in liver) or pyruvate (in muscle)

Answer 255

1. Diabetes mellitus: Impaired glucose metabolism 2. Phenylketonuria: Phenylalanine metabolism disorder 3. Glycogen storage diseases: Impaired glycogen metabolism 4. Fatty acid oxidation disorders: e.g., Medium-chain acyl-CoA dehydrogenase deficiency 5. Urea cycle disorders: e.g., Ornithine transcarbamylase deficiency

Answer 256

1. Activation: Fatty acid → Fatty acyl-CoA 2. Transport into mitochondria via carnitine shuttle 3. β-oxidation cycle: a. Dehydrogenation (FAD → FADH2) b. Hydration c. Dehydrogenation (NAD+ → NADH) d. Thiolysis (CoA-SH) 4. Acetyl-CoA enters Krebs cycle

Answer 257

* Inhibited by high levels of acetyl-CoA and NADH * Stimulated by glucagon and epinephrine * Inhibited by insulin

Answer 258

1. Activation: Fatty acid + CoA + ATP → Fatty acyl-CoA + AMP + PPi 2. Carnitine shuttle: a. Fatty acyl-CoA + Carnitine → Fatty acyl-carnitine + CoA b. Transport across inner mitochondrial membrane c. Fatty acyl-carnitine + CoA → Fatty acyl-CoA + Carnitine 3. Fatty acyl-CoA enters β-oxidation cycle

Answer 259

Rationale: Ketogenesis occurs when glucose is scarce and fatty acid oxidation is high, providing alternative fuel for the brain. Pathway: 1. Acetyl-CoA → Acetoacetyl-CoA 2. Acetoacetyl-CoA + Acetyl-CoA → HMG-CoA 3. HMG-CoA → Acetoacetate 4. Acetoacetate → β-hydroxybutyrate or Acetone Major intermediates: Acetoacetyl-CoA, HMG-CoA Major products: Acetoacetate, β-hydroxybutyrate, Acetone (ketone bodies)

Answer 260

1. Transamination: Transfer of amino group to α-ketoglutarate, forming glutamate 2. Oxidative deamination: Removal of amino group as ammonia by glutamate dehydrogenase 3. Urea cycle: Conversion of ammonia to urea for excretion

Answer 261

Urea cycle steps: 1. Carbamoyl phosphate synthesis 2. Citrulline formation 3. Argininosuccinate synthesis 4. Argininosuccinate cleavage 5. Arginine cleavage to urea Key regulatory steps: * Carbamoyl phosphate synthetase I (rate-limiting) * N-acetylglutamate (allosteric activator)

Answer 262

Glucogenic amino acids: Can be converted to glucose Examples: Alanine, Aspartate, Glutamate Ketogenic amino acids: Can be converted to ketone bodies Examples: Leucine, Lysine Some amino acids are both glucogenic and ketogenic (e.g., Phenylalanine, Tyrosine)

Answer 263

Sources of ammonia: 1. Amino acid deamination 2. Bacterial action in the gut 3. Glutamine breakdown in the kidney Uses of ammonia: 1. Urea synthesis 2. Glutamine synthesis 3. Nucleotide synthesis Nitrogen balance: The state where nitrogen intake equals nitrogen excretion. Positive balance indicates growth or tissue repair, while negative balance suggests catabolism or inadequate protein intake.

Answer 264

Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, Valine Nonessential amino acids (can be synthesized): Alanine, Arginine, Asparagine, Aspartate, Cysteine, Glutamate, Glutamine, Glycine, Proline, Serine, Tyrosine Metabolic sources of nonessential amino acids: 1. Transamination of keto acids 2. Conversion from other amino acids 3. Synthesis from metabolic intermediates (e.g., 3-phosphoglycerate for serine)

General Principles Week 1 to 4 Flashcards

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