bio cheat sheets Flashcards
(122 cards)
1
Q
For lipids, what is the:
monomer:
polymer:
linkage type:
And what are 3 types of lipids?
A
monomer: hydrocarbons
polymer: hydrocarbon chain
linkage type: covalent carbon-carbon
Types of lipids:
1. Triglycerides (glycerol + 3 fatty acids)
2. Phospholipids (2 fatty acids + phosphate group attached to glycerol backbone)
3. Steroids (three 6-membered rings + one 5-membered ring)
Note: Porphyrins (4 joined pyrrole rings with a center metal atom) are NON-lipids, but commonly associated with lipid membranes
2
Q
Nucleolus is what?
A
the site of ribosome (rRNA) synthesis
3
Q
Rough ER vs smooth ER
A
Rough ER: has ribosomes attached to the structure, functions to synthesize and store proteins
Smooth ER: functions to synthesize lipids and steroid hormones for export
4
Q
What is Michalis Constant (Km)?
A
(Km): The substrate concentration at which the rate of the reaction is half of the maximum velocity
* Inversely represents binding affinity
* Small Km= less substrate needed to reach Vmax (i.e., higher binding affinity)
5
Q
What occurs where, and in what order for cellular respiration (glycolysis, etc)
A
- Glycolysis (CYTOPLASM)
- Transformation of pyruvate into acetyl CoA (MITOCHONDRIAL MATRIX)
- Krebs cycle (MITOCHONDRIAL MATRIX)
- Oxidate phosphorylation (MITOCHONDRIAL INNER MEMB.)
6
Q
What are the important enzymes in glycolysis?
A
Hexokinase: The first “committed” step of glycolysis, transforms glucose to glucose-6-phosphate, consuming 1 ATP. Phosphorylating glucose is irreversible and prevents it from leaving the cell.
Phosphofructokinase (PFK): Adds second phosphate, committing molecule to glycolysis.
7
Q
Where do each part of photosynthesis occur?
- Outer Membrane
- Granum
- Thylakoid
- Thylakoid Membrane
- Thylakoid lumen
- Intermembrane Space
- Inner Membrane
- Stroma
- Stroma Lamallae
A
- Outer Membrane
- Granum – Stacks of thylakoids
- Thylakoid
- Thylakoid Membrane – Location of the ETC (Non-Cyclic Photophosphorylation)
– Structure which absorbs light - Thylakoid lumen – Location of photolysis. H+ ions accumulates due to ETC
- Intermembrane Space
- Inner Membrane
- Stroma – Location of the Calvin Cycle
- Stroma Lamallae - Location of Cyclic Photophosphorylation
8
Q
Describe the light reaction
A
- The electrons (e-) trapped by PSII are energized by light
- 2 excited e- are passed to a primary e- acceptor and move through the ETC
- These 2 e- lose their energy, which is used to form ~ 1.5 ATP
The ETC ends at PSI. e- are re-energized and passed to a different primary e- acceptor. e- can now either go through the cyclic or non-cyclic path:
Cyclic:
- 2 e- from PSI go back through the first ETC and generate 1 ATP
- These 2 e- are recycled into PSI and can either go through the cyclic or non-cyclic pathway again
Noncyclic:
- 2 e- go through an ETC and combine with NADP+ & H+ to form NADPH
- This NADPH is used in the Calvin Cycle to create glucose
9
Q
What is photolysis?
A
Occurs in photosynthesis
H2O splits into 2H+, 2e-, and 1⁄2 O2.
- 2H+ is used for NADPH formation
- The 2 e- lost in PSII is replenished through this process
- 1⁄2 O2 is released as gas
Photolysis occurs at PSII.
10
Q
What is chemiosmosis in photosynthesis?
A
Uses H+ gradient to create ATP.
H+ accumulates in the thylakoid lumen:
1. H+ is released into the lumen through photolysis
2. Between PSII and PSI, Cytochromes bring H+ into the lumen from the stroma. This creates a pH and an electrical gradient
- ATP Synthase uses a gradient to turn ADP into ATP
- This ATP is used in the Calvin Cycle to create glucose
Chemiosmosis occurs across the Thylakoid membrane.
11
Q
Describe the dark rxn/Calvin cycle
A
In photosynthesis, purpose: Fixes Carbon Dioxide (CO2) into glucose (2 G3P).
- Carboxylation: 6 CO2 + 6 RuBP –> 12 PGA
Reaction is catalyzed by the enzyme RuBisCo. - Reduction: 12 ATP + 12 NADPH converts 12 PGA to 12 G3P or 12PGAL
The byproducts, NADP+ & ADP, go into non-cyclic photophosphorylation. - Regeneration: 6 ATP convert 10 G3P to 6RuBP
- Carbohydrate Synthesis: Remaining 2 G3P used to form glucose
The Calvin cycle is light independent; however, it requires the high energy molecules, NADPH & ATP, produced in the light reaction.
12
Q
What are the alternatives to C3 photosynthesis?
A
C4:
- Alters location of photosynthesis
- CO2 moved to bundle sheath cells to minimize photorespiration & H2O loss
- Produces an intermediary 4-carbon compound & uses 1 extra ATP
CAM:
- Alters timing of photosynthesis
- Fixes CO2 at night instead of
day to minimize photorespiration & H2O loss
13
Q
________ produce the spindle fibers that will separate sister chromatids during anaphase
A
Centrioles
Note: Animal cells have cellular structures called centrosomes, each centrosome contains a pair of centrioles
14
Q
What are Mendel’s Laws of Inheritance?
A
- The Law of Segregation
- During Anaphase 1, homologous chromosomes segregate, resulting in haploid gametes that contain only one allele per gene - The Law of Independent Assortment
- The lining up & separation of one pair of homologous chromosomes does not influence that of a different pair of homologous chromosomes - The Law of Dominance
- A dominant allele masks the effect of a recessive allele
15
Q
What is pleiotropy?
A
A type of pattern of inheritance where a single gene controls for the expression of multiple phenotypic traits (e.g., a single gene controls a plant’s height, color, and texture)
16
Q
What is polygenic inheritance?
A
A type of pattern of inheritance where many genes interact to shape a single phenotype, often with continuous variation (e.g., height)
17
Q
What is epistasis?
A
A type of pattern of inheritance where one gene affects the phenotypic expression of an independently inherited gene
(e.g, baldness: 1st gene controls whethere one is bald or not, 2nd controls the hair colour)
18
Q
What are linked genes?
A
Linked genes reside close together on a chromosome, making them less likely to be separated by recombination during meiosis, and more likely to be inherited together
19
Q
What is penetrance vs expressivity?
A
Penetrance: The proportion of individuals with a specific genotype will express the corresponding phenotype
Expressivity: The variation of a phenotype for a specific genotype
20
Q
On a pedigree, describe how the following would appear:
Autosomal dominant
Autosomal recessive
X-linked dominant
X-linked recessive
A
Autosomal dominant:
- can NOT skip generations
- affects males and females equally
- two (heterozygous) affected parents can have unaffected offspring
Autosomal recessive:
- can skip generations
- affects males and females equally
- two (heterozygous) unaffected parents can have affected offspring
X-linked dominant:
- can NOT skip generations
- affects males and females equally
- affected FATHERS ALWAYS have affected DAUGHTERS
X-linked recessive:
- can skip generations
- affects MALES more commonly than females
- affected MOTHERS always have affected SONS
- normal fathers NEVER have affected daughters
21
Q
What is the function of each of the following:
Colchichine
Proto-oncogenes
Tumor suppressor genes
A
Colchicine arrests mitosis by interfering with mitotic spindle formation; it can prevent cells from replicating and has anticancer effects
Proto-oncogenes stimulate normal growth; if mutated become oncogenes (cancer-causing genes)
Tumor suppressor genes make proteins that help control cell growth; if mutated may lead to cancer
22
Q
Describe the following terms
Operons
Promoter
Operator
A
Operons: Gene clusters that control
transcription and consist of promoter,
operator, structural genes
- Promoter: DNA sequence where RNA Polymerase attaches to
- Operator: Region that can block the action of RNA Polymerase if occupied by a repressor
- Structural genes: Genes that code for proteins that are to be produced
23
Q
Describe the Lac operon vs Trp operon
A
Lac Operon: Operon in prokaryotic cell that encodes genes required for processing of lactose
- Presence of lactose induces the operon to produce lactose breakdown enzymes
- allolactose (rearranged lactose) binds to the lac repressor and makes it LET GO of the operator; RNA polymerase can now transcribe the operon
Trp Operon: Operon: A group of genes necessary to synthesize tryptophan in prokaryotic cells
- when tryptophan is present, trp respressor binds to operator; RNA synthesis is blocked
- in absence of tryptophan, the repressor dissociates from operator; RNA synthesis process
24
Q
Transformation vs transduction
A
Transformation:
A competent recipient bacterium takes up free DNA from the surrounding
Transduction:
DNA is transferred from one bacterium to another by a bacteriophage (virus that infects bacteria)
25
Genome size vs gene number vs gene density
Genome size:
The total number of NUCLEOTIDES an organism has
- Unrelated to organism complexity (ex. A grape may have a larger genome than a human)
- Eukaryotes have larger genomes than prokaryotes
- Prokaryotes lack introns and have less “junk DNA” (DNA that does not code for anything)
Gene number:
The total number of GENES (sequences of nucleotides that code for a product)
- No correlation between genome size and # of genes
- Eukaryotes have more genes than Prokaryotes
- Humans have less genes than expected for their complexity due to alternative splicing (single gene may be used to make multiple different protein products)
Gene density:
The ratio of gene number to genome size
- Eukaryotes have a lower gene density
than prokaryotes because the majority of eukaryotic genome is noncoding DNA
26
Histones have a tail made of ______ amino acids (if mutated, gene expression could be affected --> increased or decreased)
LYSINE
27
What are two epigenetic conditions we should know? How do they work?
Prader-Willi Syndrome:
A set of genes are only expressed on the father’s Chromosome 15, while the mother’s genes are imprinted
- When the genes on the father’s copy are mutated or deleted, the child develops health conditions
Angelman Syndrome:
A (different) set of genes is only expressed on the mother’s Chromosome 15, while the father’s genes are imprinted
- If the maternal copies of the gene are deleted or mutated, health conditions result
28
How are queen bees formed?
In a honeybee colony, although genetically identical, the queen is larger, lives longer, develops more rapidly, and has functional ovaries – compared to the workers
- The queen larva is fed a special diet of royal jelly that blocks DNA methylation, allowing for the expression of different genes, resulting in a different phenotype
29
What are each of the following used for?
- Light microscope
- Scanning electron microscope
- Transmission electron microscope
- Confocal Laser Scanning microscope
Light Microscope: Use visible light to view a thin sample
Scanning Electron Microscope: Used to view surface of 3D objects with high resolution
Transmission Electron Microscope: Used to view thin cross sections and internal structures within samples at very high magnification
Confocal Laser Scanning Microscope/Fluorescence: Can observe
specific parts of a cell using fluorescent tagging antibodies (ex: used to view chromosomes during mitosis)
30
What are the steps of PCR?
PCR creates a large amount of DNA by amplifying a DNA sample through the following steps:
1. Denaturation: High heat separates double stranded DNA
2. Annealing: Sample is cooled so primers attach to separated strands
3. Elongation: Polymerase synthesize new strands
31
What are the steps of blotting?
Blotting techniques are used for identifying specific fragments of DNA, RNA, or protein
Blotting Methodology:
1. Electrophoresis is used to separate sample
2. Sample is transferred to nitrocellulose gel
3. Probe is added to hybridize and mark target fragment
32
Dideoxy Chain Termination is based on the principle that during DNA synthesis, addition of a nucleotide requires a _______________________ of the last nucleotide of the growing DNA strand
free OH group on the 3ʹ carbon of the sugar of the last nucleotide of the growing DNA strand
33
____________ = first type of living organisms to appear
anaerobic prokaryotes = first types of living organisms to appear
34
What is the cell wall composition of each of the following
Eukaryotic
Prokaryotic (archaea)
Prokaryotic (bacteria)
Eukaryotic
- plants: cellulose
- fungi: chitin
Prokaryotic (archaea)
- pseudomurein
Prokaryotic (bacteria)
- peptidoglycan
35
What are sporangium in fungi?
Sporangium: Multicellular organ where meiosis occurs, and haploid cells (spores) are formed
36
What are rhizoids in fungi?
Small branching hyphae that anchors structures to the ground
Note: unlike roots, they are NOT composed fo tissues & lack specialized conducting cells
37
Non-filamanteous vs filamentous fungi, and examples
Non-filamentous fungi:
- Unicellular
- Includes yeasts
- Asexual reproduction by budding via mitosis
- Replicate genetic material and pinch off a portion of cytoplasm and cell membrane to form a new cell
Filamentous fungi
- Multicellular
- Includes molds & mushrooms
- Sexual or asexual reproduction
- Mushrooms grow outward from mycelium
38
What is mycelium?
Mycelium: Network of fungi filaments (hyphae) that connect fungi together
- Secrete enzymes that break down organic matter
- Releases nutrients for absorption by hyphae
- Allows fungi to be effective decomposers
Pro-Tip: All are heterotrophic saprophytes
39
What are hyphae and the types?
Hyphae: Filamentous branches produced by multicellular fungi as they grow
1. Septate hyphae
- Have septa (cell walls that separate hyphae)
2. Coenocytic hyphae
- No division of hyphae (no cytokinesis during cell division)
- Multinucleated
40
Describe the angiosperm lifecycle
1. Meiosis in Ovary (Female)
– Megasporocyte, the megaspore mother cells (2n), are converted into four megaspores (n) via meiosis
2. Mitotic Divisions Produce Female Gametophyte
– One megaspore (n) survives and undergoes mitosis once fertilized to produce the egg cell and polar nuclei
I. Two Synergid Cells: Help flank the cell and help attract/guide pollen tube to the female gametophyte
II. Antipodal Cells: Unknown Function
3. Meiosis Within Anther
– Microsporocytes (2n) → four microspores (n) via meiosis
4. Mitotic Divisions Produce Male Gametophyte
– Microspore undergoes mitosis producing male gametophyte (n), or the pollen grain.
Male gametophyte (n) contains generative cell (forms into two sperm) and tube cell (forms into pollen tube)
5. Pollen Tube Elongates Through the Style
– Upon reaching ovule, two sperm are discharged
6. Double Fertilization Occurs
– One male gamete (n) fuses with the female egg gamete (n) to form an embryo/zygote (2n) & another male gamete fuses with polar nuclei to form endosperm (3n)
7. Zygote Develops into Embryo
41
Describe xylem and what kinds of cells are present
Xylem:
- conducts water and minerals throughout the plant
- provide mechanical support
Xylem cells:
1. Tracheids: long and tapered, water passes laterally from one to another through pits
2. Vessel elements: short and wide, have little to no taper at ends, perforations allow for H2O to pass from one vessel element to another
42
What are endosperm?
Primary storage tissue in angiosperm seeds
43
What are cotyledons?
Transfer nutrients from endosperm to embryo in angiosperm seeds
44
Angiosperm seeds are equivalent to __________________
Angiosperm seeds are equivalent to fertilized animal eggs
45
What do each of the following plant hormones do?
Auxin
Gibberellins
Cytokinins
Absisic Acid
Ethylene Gas
Auxin: Influences plant’s response to light + gravity to stimulate growth/elongation
Gibberellins: Promote flower + stem elongation
Cytokinins: Stimulate cytokinesis (cell division)
Abscisic Acid: Inhibits growth and promotes
seed dormancy
Ethylene Gas: Promotes fruit ripening, flower
production, and leaf abscission
46
Describe the structure/function of each of the following
Epidermis
Palisade mesophyll
Vascular bundles
Guard cells
Spongy mesophyll
Stomata
All apart of the leaf structure
Epidermis:
- Protective layer covered w/ cuticle to reduce transpiration (water loss through evaporation)
Palisade mesophyll:
- Has cells w/ chloroplasts and is the primary site for leaf PHOTOSYNTHESIS
Vascular bundles:
Consist of xylem and phloem – surrounded by bundle sheath cell
Guard cells:
- Specialized epidermal cells to control opening of stomata and permit gas exchange
Spongy mesophyll:
- Intracellular spaces allow for gas travel
Stomata:
- Microscopic pore in epidermis that allows for gas exchange between plant and external environment
- When open, CO2 can enter the leaf where photosynthesis can then occur to make sugar
* However: risk of desiccation from transpiration (water loss)! → Regulation is important
- When closed, water loss is minimized, but CO2 cannot enter the cells of the plant which prevents the Calvin Cycle from taking place (but no risk of transpiration)
47
Primary vs secondary plant growth
Primary: increases LENGTH of plant
Secondary: increases GIRTH of plant
48
Antigenetic shift vs antigenetic drift
Antigenic shift: Viruses mix genes to increase host ranges; difficult to treat
Antigenic drift: Minor changes in viruses allow for infection of same host species
49
What are prions and viroids?
Prions:
Infectious misfolded proteins that cause other proteins to misfold into the prion form
Viroids:
Single stranded RNA molecules that infect plants
50
* Pleurae: Membranous cover with 2 layers
* Visceral pleura: lines ________________
* Parietal pleura: lines ________________
* Pleurae: Membranous cover with 2 layers
* Visceral pleura: lines lung surface
* Parietal pleura: lines inside of chest cavity
51
What are the main 3 types of pseudostratified cells in trachea and bronchi and their functions
Trachea and bronchi have pseudostratified cells
3 main types:
1. Goblet cells: secrete mucus
2. Basal cells: produce new cells
3. Cilia cells: sweep debris trapped by mucus
52
What are the chemoreceptors in the respiratory system?
Measure concentrations of specific gases and acids and uses that information to tell the brain what changes in respiration need to be made
Central chemoreceptors (in medulla):
- indirectly monitor [H+] in the cerebrospinal fluid
Peripheral chemoreceptors (in carotid arteries and aorta):
- function to monitor the atrial concentrations of CO2, O2, and pH via H+
53
A ____ shift on the oxygen dissociation curve results in oxygen being held more tightly by hemoglobin.
LEFT
54
Systole: _________ of atria/ ventricles
Diastole: _________ of atria/ ventricles
Systole: Contraction of atria/ ventricles
Diastole: Relaxation of atria/ventricles
55
Deoxygenated blood enters the right atrium via ___________.
Deoxygenated blood enters the right atrium via superior and inferior vena cava.
56
Describe the juxtaglomerular apparatus briefly
Macula Densa: Monitors filtrate pressure in kidney tubules
- If low Blood Pressure → adrenal cortex is signaled to synthesize aldosterone → more water is reabsorbed from the kidney back into the blood → Blood pressure increases/normalizes
57
Aldosterone vs ADH
Aldosterone:
Increases Na+ reabsorption from the kidney tubules into the bloodstream → water follows Na+ out of the kidney and back into the blood → water retention in blood is increased
ADH:
Increases collecting duct permeability to water → water is reabsorbed out of kidney tubule and back into the bloodstream → urine becomes more concentrated while blood pressure increases
- Alcohol & coffee block synthesis of ADH, leading to more dilute urine flow
58
Mammals, sharks, amphibians:
convert NH3 → ________
Birds, insects, reptiles: secrete ________
Mammals, sharks, amphibians:
convert NH3 → Urea
Birds, insects, reptiles: secrete Uric
Acid
59
Food enters the stomach from the esophagus through the lower esophageal/_______ sphincter
Food enters the stomach from the esophagus through the lower esophageal/CARDIAC sphincter
60
Stomach cells and what they do:
- Mucus cells
- Chief cells
- Parietal cells
- G cells
Mucus cells:
- Secrete mucus
- Lubricates & protects the stomach’s epithelial lining
Chief cells:
- Secrete pepsinogen, which is activated by low pH in stomach
- Converts to pepsin (digests proteins)
Parietal cells:
- Secrete HCl
G cells:
- Secrete gastrin, which stimulates parietal cells to secrete stomach acid
61
Bile: created in ______ & stored in ________
* If bile cannot be released, _____ breakdown
would be compromised.
Bile: created in LIVER & stored in GALL BLADDER
* If bile cannot be released, LIPID breakdown
would be compromised.
62
______ duct + ______ duct --> common bile duct
Cystic duct + hepatic duct --> common bile duct
63
3 segments of small intestine in order and their general functions
1. Duodenum: Continues breakdown of starches and proteins & remaining food types (majority of digestion occurs here)
2. Jejunum: Majority absorption of nutrients occurs here.
3. Ileum: Absorption continues; contains Peyer’s patches (lymphoid tissue)
64
Digestive Enzyme Flow
Pancreas:
- Secretes bicarbonate and digestive enzymes to the duodenum
Key digestive enzymes include:
- Trypsin/chymotrypsin (digest proteins)
- Lipase (digest lipids)
- Amylase (digest carbohydrates)
- Nucleases (digests nucleic acids)
Digestive Enzymes initially exist as zymogens (inactive). They are then cleaved in the small intestine to their active form
Digestive Enzyme Flow:
Produced in pancreas --> flow from pancreatic duct into duodenum --> neutralizes acidic chyme from stomach & allows for digestion to occur
65
Limbic system?
Limbic system = hippocampus, amygdala, and hypothalamus
(behavioral and emotional responses)
66
Diencephalon?
Diencephalon subdivision = thalamus, hypothalamus, and pineal gland
67
What is each of the lobes responsible for?
Cerebrum contains cerebral cortex; divided by lobes (telencephalon subdivision):
i. Frontal: Conscious thought (attention)
ii. Parietal: Sensory; somatosensation, proprioception
iii. Temporal: Sound processing/interpretation
iv. Occipital: Visual input
68
What are the different neurotransmitters:
- ACh
- Amino acids
- Gases
- Amino acid derived (biogenic amines)
Acetylcholine (ACh):
- Binds to ACh receptors on post-synaptic membrane for nerve transmission
- Secretion at neuromuscular junctions = contraction or relaxation of muscles (PNS)
- Recycled back to presynaptic vesicle via acetylcholinesterase --> nerve signal terminated; postsynaptic neuron cannot depolarize
Amino acids:
- Glutamate: Most common CNS neurotransmitter in vertebrates; excitatory
- GABA: Found in brain; inhibitory
- Glycine: Found in CNS outside brain; inhibitory
Gases:
- Synthesized and released on demand; not stored in vesicles (e.g., NO)
Amino acid derived (biogenic amines):
- Epinephrine (E) and Norepinephrine (NE) --> act in sympathetic nervous system
- E = bronchodilation and vasodilation to lungs and skeletal muscles; vasoconstriction to the digestive system and kidneys
69
Describe each of the following
myofibrils
sarcomeres
sarcoplasm
sarcolemma
mitochondria
1. Myofibrils: contain microfilaments divided into sarcomeres
2. Sarcomeres: individual contractile units separated by a border (Z-line)
3. Sarcoplasm reticulum: stores Ca+2 and surrounds myofibrils
4. Sarcoplasm: same thing as cytoplasm, but
referred to as sarcoplasm in muscles
5. Sarcolemma: plasma membrane of muscle cells that can propagate action potentials that are invaginated by T-tubules (channels for ion flow)
6. Mitochondria: present in large amounts in myofibrils
70
Describe the neuromuscular pathway steps
1. Action potential of a neuron releases acetylcholine at a neuromuscular junction
2. An action potential is then generated on the sarcolemma and throughout T- tubules
3. The sarcoplasmic reticulum releases
Ca2+
4. Ca2+ binds to troponin on the actin helix, allowing myosin to bind
5. Myosin cross-bridges form and contraction occurs as depicted in the “Sliding Filament Model”
Sliding filament model:
1. Ca2+ exposes binding sites on actin: Binds to troponin → pulls back tropomyosin → exposes attachment sites
2. Myosin head attaches to actin filament: This forms a cross-bridge
3. Inorganic phosphate is released from the myosin head: This initiates a power stroke (muscle contracts bringing the Z-lines together). After the power stroke, ADP is released, and myosin remains bound to actin
4. New ATP attaches to the myosin head --> cross bridges unbind: Initially, the myosin head is bound to the actin filament from the previous contraction. When ATP binds to the myosin head, myosin & actin unbind.
If no ATP is available, the muscle is stuck in contraction (ex: rigor mortis)
5. When ATP is converted to ADP + Pi, the myosin head is cocked back: The sliding filament model is ready for another cycle of contraction
71
What are the two muscle types (and their characteristics) capable of contracting without nerve stimuli?
1. Cardiac muscle
- Striated appearance
- One or two central nuclei
- Cells separated by intercalated discs that have gap junctions
- A lot of mitochondria
2. Smooth muscle
- Lacks striation
- Contains one central nucleus
- Stimulated by the autonomic nervous system
- Does not utilize sarcomeres
72
Cartilage is vascular or avascular?
AVASCULAR!!
73
Describe each of the following terms
Osteon
Lamellae
Lacunae
Volkmann's canals
Haversian canals
Medullary cavity
Osteon:
- Functional unit of compact bone; includes lamellae + Haversian canals
Lamellae:
- Concentric rings of compact bone that form the Haversian canals
Lacunae
- Osteocytes trapped b/w lamellae reside here & exchange nutrients via small canals (canaliculi)
Volkmann's canals
- Connects blood vessels, & lymph vessels contained in Haversian canal
Haversian canals:
- Passageway for nerves, blood & lymph vessels
Medullary cavity:
- Hollow part of bone surrounded by compact bone
- Contains yellow bone marrow (fat) and red bone marrow (the site of hemopoiesis or red blood cell development)
74
Compact vs spongy/cancellous bone
Compact bone: Very organized, dense bone
Spongy/cancellous bone:
- Less dense consisting of an interconnecting
lattice of bony spicules called trabeculae.
- Spaces are filled with red bone marrow.
75
Which layer of skin is held together by desmosomes?
Stratum spinosum
76
What do each of these epidermal cells do:
Melanocytes
Merkel cells
Keratinocytes
Langerhands cells
Melanocytes:
* Transfers skin pigment melanin to keratinocytes
Merkel cells:
* Attach to sensory neurons and functions in touch sensations
Keratinocytes:
* Produce keratin
* Help waterproof
Langerhans cells:
* Interact with immune cells
77
Describe the structure and functions of the dermis. What are the two layers?
The dermis is the second layer of skin and is highly vascularized. It is connected to the epidermis above via the basement membrane.
Comprised of two individual layers:
1. The Papillary Region
- Vascular network within upward projecting papillae that helps supply nutrients to epidermis & regulates temperature
- Papillae contain Meisner’s corpuscles (sensory touch receptors)
2. The Reticular Region
- Region with dense connective tissue, collagen & elastic fibers; packed with glands, sweat gland ducts, fat, and hair follicles
78
What is the hypodermis structure/function?
- subcutaneous
- Consists of areolar & adipose tissue
- Functions in fat storage, heat insulation & shock absorption
- Contains pressure sensing nerve ending & passage for blood vessels
79
Describe the function of each WBC, and which are phagocytic/nonphagocytic?
Phagocytic leukocyts (internal non-specific defense):
- Engulf foreign particles, bacteria, and dead cells via phagocytosis
1. Neutrophils – Function in the destruction of
pathogens in infected tissues
2. Monocytes – Circulate in blood until they move into tissues via diapedesis where they develop into macrophages
3. Macrophages – In tissues, they phagocytize cell debris and pathogens and are derived from monocytes
4. Dendritic cells – Ingest pathogens and stimulate the acquired immune response
Non-phagocytic leukocytes (Internal non-specific defense):
1. Mast Cells – Function in an allergic response, inflammatory response, and anaphylaxis
2. Eosinophils – Surround and destroy multicellular parasites
3. Basophils – Release histamine in the inflammatory response and recruited to tissues when needed
4. NK Cells – Attack abnormal body cells, either tumors or pathogen-infected cells.
80
Relative abundance of eosinophils, monocytes, neutrophils, and lymphocytes? (largest to smallest)
Relative abundance of the Leukocytes:
Neutrophils > Lymphocytes > Monocytes > Eosinophils
81
What are B cells? Where do they originate/mature?
* B cells originate and mature in the bone marrow, and are activated in response to foreign antigens
* Antibodies are glycoproteins produced by B cells that are specific to an antigen and have 5 classes: IgA, IgD, IgE, IgG, and IgM
82
What is clonal selection?
When a foreign antigen activates a B cell, proliferation (or expansion of the B cell population) occurs, thus forming daughter B cells. The two main types of daughter B cells are Plasma Cells and Memory Cells
83
What are T-cells? Where do they originate/mature?
What are the roles of cytotoxic vs helper vs suppressor vs memory T cells?
T cells originate in the bone marrow but mature in the thymus, and have antigen receptors
1. Cytotoxic T cells - killer T cells that destroy by releasing perforin protein and via lysis
2. Helper T cells - stimulate activation of B cells, cytotoxic T cells, and suppressor T cells
3. Suppressor T cells - play a negative feedback role in the immune system
4. Memory T cells - similar in function to Memory B cells
84
What is the humoral response vs cell-mediated response?
Cell-mediated and humoral response are both possible pathways for the adaptive immune system to regulate an immune response
Humoral response (antibody-mediated response):
- occurs when extracellular pathogens are recognized in the blood or lymph
- B-cells are then stimulated to produce antibodies that lead to the destruction of the pathogen
* B-cells are critical to the humoral response
Cell-Mediated Response:
- occurs when an infected cell is recognized and bound by a T-cell
- The T-cell then activates other T-cells, causing proliferation that leads to lysis of the infected cell
* T-cells are critical to cell-mediated response
85
All cells with a nucleus have MHC _, but only Antigen Presenting Cells have MHC _
All cells with a nucleus have MHC 1, but only Antigen Presenting Cells have MHC 2
86
Active vs passive immunity (natural/artificial) means what?
Active and passive immunity are two divisions of adaptive immunity
Active immunity:
Acquired after direct exposure to an infection/vaccine
- Natural = Antibodies made after exposure to pathogen
- Artificial = antibodies made after getting a vaccine
Passive immunity:
Acquired from external sources
- Natural = Antibodies transferred from mother to baby
- Artificial = Antibodies given to you via a serum injection
87
The three types of antigen presenting cells are ___________, ___________, and ___________.
Macrophages, dendritic cells, and B cells
88
What are the tyrosine derivate hormones, and their characteristics (water/lipid soluble)
Thyroid hormones:
- Lipid-soluble, bind to receptors in nucleus, and require protein carrier in blood
Catecholamines:
- Water-soluble, bind receptors on target tissue, and mainly act via secondary messenger cAMP
89
What are the secondary messengers we should know?
IP3, cAMP, Calcium, DAG
90
What kinds of cells are each secreted by :
Glucagon, insulin, somatostatin
Glucagon *: alpha cells
Insulin *: beta cells
Somatostatin *: delta cells
- Inhibits release of insulin & glucagon
91
What are the tropic hormones, and what do they do?
ACTH *:
Stimulates adrenal cortex → releases glucocorticoids
TSH *:
Stimulates thyroid gland to release thyroid hormones
LH *
♀: Stimulates corpus luteum formation
♂: Stimulates interstitial cells of testes to produce testosterone
FSH *
♀: Stimulates maturation of ovarian follicles to secrete estrogen
♂: Stimulates seminiferous tubule maturation & sperm production
92
What are the nontropic homrones and what do they do?
Directly stimulate target organs
GH*: Stimulates bone & muscle growth
Prolactin*: Stimulates milk production
93
What hormones does the posterior pituitary synthesize/release?
Does NOT synthesize hormones
Stores ADH & oxytocin for release
- ADH (vasopressin)*: Increases reabsorption of water by increasing permeability of nephron's collecting duct
- Oxytocin*: Increases strength of uterine contractions; stimulates milk ejection; induces maternal behavior
94
What hormones does the pineal gland affect?
Secretes melatonin: Regulates circadian rhythm (sleep)
95
What hormones does the thymus involve
Immune function
- Secretes thymosins that stimulate white blood cells to become T-cells
96
What does the parathyroid gland do in terms of hormones?
PTH *
Antagonistic to the function of calcitonin
Raises Ca2+ levels in blood by:
- Stimulating osteoclasts to breakdown bone
- Increasing kidney reabsorption of calcium
- Increasing calcium uptake from the gut
97
What hormones does the thyroid gland involve
Thyroxine (T4) & Triiodothyronine (T3) (Y)
- ↑ basal metabolic rate in body
- Iodine is necessary to synthesize thyroid hormones and prevent goiters
Calcitonin *
- Stimulates osteoblast activity (builds up bone by using calcium in the blood)
98
What hormones do the testes & ovaries involve?
Note: all steroid hormones
Testosterone : Increases spermatogenesis, secondary sex characteristics
Estrogen : Menstrual cycle regulation, secondary sex characteristics
Progesterone : Menstrual cycle regulation, pregnancy
99
What hormones do the adrenal glands involve (adrenal medulla vs adrenal cortex)?
Adrenal medulla:
Epinephrine & Norepinephrine (Y)
- “Fight or flight” catecholamines
- Converts glycogen to glucose [↑ blood
glucose]
- Vasoconstrictor to kidneys and bladder
- Vasodilator to skeletal muscle, increased heartbeat
- Bronchodilation
- Prepares body for
intense physical activity
Adrenal cortex:
1. Glucocorticoids (cortisol & cortisone) (STEROID HORMONES)
- Raise blood glucose levels
- Degrades adipose tissue to use as energy
2. Mineralocorticoids (aldosterone) (STEROID HORMONES)
- ↑ reabsorption of Na+ and excretion of K+ in kidneys
- Causes passive reabsorption of water in nephron which raises blood pressure
100
Semiferous tubules, sertoli cells, vs Leydig cells
Seminiferous tubules within the testis produce sperm. Contain the following cells:
- Sertoli cells: Stimulated by FSH and surround and nurture the sperm
- Interstitial cells (Leydig cells): Secrete male hormones (E.g., testosterone and androgens) in the presence of LH
101
Epididymys
Coiled tube attached to each testicle that serves as the site of final sperm maturation and storage.
102
seminal vesicles
Seminal vesicles: Excrete fluid into the vas deferens upon ejaculation.
103
Pathway of sperm
S – Seminiferous tubules
E – Epididymis
V – Vas deferens
E – Ejaculatory duct
n – nothing
U – Urethra
P – Penis
104
Landmarks of Fetal Development
Week 5: Heart begins beating
Week 8: Development of embryo has reached fetus stage
Week 40: Development has reached full term
105
Follicular, ovulation, and luteal phase (brief)
Follicular phase: development of egg + secretion of estrogen from follicle
Ovulation: midcycle release of egg à surge of LH
Luteal phase: secretion of estrogen + progesterone from corpus luteum after ovulating
106
Female hormonal contraception explanation
1. Estrogen + progesterone levels are spiked artificially high via medication, causing a negative feedback loop
2. Negative feedback loop on hypothalamus/anterior pituitary suppresses LH/FSH surge
3. Ovulation cannot occur due to lack of LH surge
4. Sperm cannot fertilize an egg as it was not released into the fallopian tube
107
Describe the formation of female gametes
1. Oogonia give rise to oocytes. Oogonia multiply by mitosis. In development of fetus, many oogonia begin meiosis, but stop in prophase I and now called primary oocytes. Remains until puberty
2. Primary oocytes become surrounded by single layer of granulosa cells, creating primordial follicle. Present till puberty
3. Primordial follicles develop into primary follicles when granulosa cells enlarge and increase in number
4. Secondary follicles form when fluid-filled vescicles develop and theca cells arise on the outside of the follicle
5. Mature follicles form when vesicles create a single antrum
6. Just before ovulation, primary oocyte completes meioisis I, creating a secondary oocyte and nonviable polar body
7. Secondary oocyte begins meiosis II, stops at metaphase II
8. Secondary oocyte released from ovary
9. Secondary oocyte only completes meiosis II if fertilized by a sperm cell. The completion of meiosis II forms an oocyte and a second polar body. Fertilization is complete when oocyte nucleus and sperm cell nucleus unites, creating a zygote
108
What does hCG do?
If implantation does occur, the placenta secretes human chorionic gonadotropin (hCG) which maintains the corpus luteum and stimulates it to release progesterone
--> continued release of estrogen + progesterone from corpus luteum allows for endometrium to stay intact
hCG is later replaced by progesterone from the placenta
109
Describe spermatogenesis
Process begins at puberty in the seminiferous tubules of the testes: a 2n spermatogonium undergoes mitosis and meiosis here to eventually mature into 4 sperm that then travel to the epididymis for storage until release
110
What is the male reproductive cycle
1. Hypothalamus releases GnRH
2. GnRH triggers anterior pituitary to release FSH and LH
3. FSH stimulates Sertoli cells to promote the development of the sperm (FSH stimulates spermatogenesis)
4. LH stimulates Leydig cells to release testosterone and androgens
- Injection of excess testosterone will produce a (-) feedback loop that decreases spermatogenesis
111
Describe fast vs slow block to polyspermy
Fast
- Occurs instantaneously when sperm fuses with plasma membrane
i. Sodium channels along membrane open, causing Na+ influx
ii. Depolarization of egg membrane changes charge of membrane, preventing other sperm from binding for a short duration of time
Slow
- Longer lasting block occurring after fast block
i. Depolarization of egg causes Ca2+ release from endoplasmic reticulum into cytoplasm
ii. Cortical granules fuse with membrane and release their contents outward into perivitelline space
iii. Membrane enlarges --> zona pellucida (now known as the fertilization membrane/envelope) detaches and hardens, preventing future sperm from being able to bind
� Pro-Tip: After slow block, a second meiotic division of the egg is completed
112
Determinate (mosaic) vs indeterminate (regulative) cleavage?
* Determinate (Mosaic): Cell decides its fate (what type of cell to become) early in development
i. Separated blastomere and the remaining embryo can’t form a complete organism (this is because of point 2)
ii. Removing blastomere would remove an irreplaceable and critical piece of organism
Indeterminate (Regulative): Fate of cell is determined later in development
i. Can replace missing parts or become full organism
ii. If blastomere is removed, it and the remaining embryo can form a complete organism --> resulting in 2 complete normal organisms
113
Protostome vs deuterostome
Direction of cleavage:
Type of cleavage: determinate/indeterminate?
First formation
Coelom formation
Protostome
Direction of cleavage: spiral
Type of cleavage: determinate (mosaic)
First formation: MOUTH
Coelom formation: schizocoelus
Deuterostome
Direction of cleavage: radial
Type of cleavage: indeterminate (regulative)
First formation: ANUS
Coelom formation: enterocoelus
114
What is the order for the following
morula, neurula, blastula, gastula, fertilized zygote
Fertilized zygote --> Morula --> Blastula --> Gastrula --> Neurula
115
What is blastulation?
Note: Fertilized zygote --> Morula --> Blastula --> Gastrula --> Neurula
Blastulation:
The morula (solid ball of cells) becomes a blastula (hollow sphere of cells)
* Human embryos at this stage are specifically referred to as blastocysts
116
What is gastrulation?
Note: Fertilized zygote --> Morula --> Blastula --> Gastrula --> Neurula
The blastula becomes the gastrula as cells begin to invaginate with a blastopore that will go on to become the mouth (protostome) or anus (deuterostome)
- During gastrulation, different parts of the embryo begin to interact with one another for the first time
- Embryo develops 3 germ layers: ectoderm, mesoderm, and endoderm
- Even the most primitive organisms form a gut tube (continuous tube connecting the mouth and anus) during gastrulation
117
What is embryonic induction?
Via induction, a cell can influence the development of nearby cells
- Confirmed by experimentally transplanting one part of an embryo to another to see if it causes development of new structure (E.g., transplanting an additional notochord causes a second neural tube to develop)
118
What is neurulation?
Note: Fertilized zygote --> Morula --> Blastula --> Gastrula --> Neurula
1. The notochord (which will go on to form parts of the intervertebral discs & spinal vertebrae) stimulates overlying ectoderm to thicken via induction
2. The neural plate starts to fold inwards
3. The neural plate will continue to fold and will form neural tube as it eventually pinches off
- The neural tube will go on to form the brain and spinal cord
119
What do the ectoderm, endoderm and mesoderm form?
Ectoderm:
- Epidermis layer (skin/hair)
- Adrenal medulla
- Jaw + teeth
- Sensory system
- Nervous system
Endoderm:
- Epithelial lining (GI & respiratory tract, excretory system, reproductive tract)
- Thyroid, parathyroid, and thymus
- Liver
Mesoderm:
- Circulatory system
- Lymphatic system
- Skeletal system
- Muscular system
- Adrenal cortex
- Notochord
120
Describe amphibian embryology
1. Sperm fuses with the animal pole of the egg
2. Embryo rotates 30° on its axis to form an area called the gray crescent (gray due to cytoplasm + yolk mixing)
3. Gray crescent (formed exactly opposite of the sperm’s point of entry) foretells future pattern of amphibian
4. An experiment found frog cells separated from early cleavages can grow into a frog only if they contain a portion of the gray crescent
121
Monozygotic vs dizygotic twins
Monozygotic: single sperm fertilizes an egg to
form 1 zygote --> 2 genetically identical embryos
Dizygotic: 2 eggs fertilized by 2 sperm --> regular siblings just born at the same time
122
