Teaching block 2 [1] Flashcards

Question

How are the Nitrogenous Bases connected in DNA

Answer 1

- The 2 DNA strands are connected via hydrogen bonds between the nitrogen bases of each strand (double-helix). - Double helix structure relies on the pairing of 1 pyrimidine with 1 purine, ensuring that the width of the helix remains constant - **purine A** pairs with **pyrimidine T** with **2 H** bonds - **purine G** pairs with the **pyrimidine C** with **3 H** bonds specific pairing due to complimentary shape of bases + ability to form H bonds

Answer 2

1. **Triplet code**: - Read in groups of three nucleotides, called codons. - Each codon specifies a single amino acid. 2. **Universal**: - The genetic code is almost universal across all organisms - The same codon specifies the same amino acid in most living beings. - EG in both humans + bacteria, AUG codes for methionine

Answer 3

3. **Degenerate**: - The genetic code is degenerate, * Multiple codons can code for the same amino acid. * EGGCU, GCC, GCA + GCG all code for the amino acid alanine 4. **Non-Overlapping**: - Codons are read in a continuous, non-overlapping manner - Each nucleotide is part of only one codon 5. **Start and Stop Codons**: - The codon *AUG* = start codon = signalling beginning of protein synthesis - 3 stop codons - *UAA, UAG, UGA* = signal end of protein synthesis

Answer 4

- A **codon** = Each sequence of 3 bases ( a triplet) = codes for 1 a specific amino acid There are 64 possible combinations: * 61 represent amino acids * 3 represent stop signal 20 amino acids make up the proteins in human body

Answer 5

- process where DNA produces an **exact copy of itself** - Genetic info is passed from parent to daughter cells - Basis for biological inheritance, ensuring genetic continuity - The parental DNA strand serves as a template for the synthesis of daughter nucleic acid molecules -` Results in 2 identical DNA molecules, each containing 1 parental strand + 1 newly synthesized strand` - (= **semi conservative**). **Important**: - essential for growth, reproduction + inheritance of geneic traits. - Ensures every new cell gets a complete, accurate copy of the organism's genome - innacurate copying of genetic info = mutations =diseases (eg colon+breast cancer linked to mutations in proofreading + errors in repair enzymes of replication)

Answer 6

1. Helicase 2. Binding Proteins 3. Primase 4. Polymerase 5. Ligase

Answer 7

- Helicase unzips + unwinds the DNA molecule - DNA polymerase creates a new complementary strand of DNA on each of the originals halves that were separated by helicase - New nucleotides are added through complementary base pairing: A pairs with T, and C with G - Ligase repairs gaps in the sugar-phosphate backbone between Okazaki fragments - DNA replication is semi-conservative because each daughter molecule contains one strand from the parent molecule and one new complementary strand

Answer 8

* **Role**: Unzips the DNA double helix * **Function**: Breaks the hydrogen bonds between complementary base pairs separating the 2 strands + forming a replication fork * **Importance**: Creates single-stranded DNA templates for replication

Answer 9

* **Role**: Stabilises the unwound DNA strands * **Function**: Binds to single-stranded DNA to prevent it from re-annealing (re forming hydrogen bonds) or degrading. * **Importance**: Ensures the DNA remains open + accessible for replication machinery.

Answer 10

* **Role**: Synthesises DNA primers * **Function**: creates short DNA primers on the DNA template *to provide a starting point for DNA polymerase* * **Importance**: DNA polymerase can only add nucleotides to an existing strand; primers act as a foundation for this process.

Answer 11

* **Role**: Synthesises new DNA strands * **Function**: Adds complementary nucleotides from the 5’ to the 3' end of the DNA primer + Performs proofreading to correct errors during replication. * **Importance**: Responsible for creating the new daughter DNA strand, ensuring it is complementary to the parental strand.

Answer 12

- Polymerase can only synthesize new DNA in one direction on the template strand = the 5' to 3' direction - * One set of DNA being replicated in one long strand (the **leading strand**) [5'-3'] * One replicated in small chunks called Okazaki fragments (the **lagging strand**) [3'-5'] **Okazaki Fragments** = short fragments of DNA synthesized on the lagging strand

Answer 13

* **Role**: Joins DNA fragments * **Function**: Seals the gaps between Okazaki fragments on the lagging strand by *forming phosphodiester bonds* (fuses sugar-phosphate backbone). * **Importance**: Finalises the DNA molecule, ensuring the strands are continuous + complete.

Answer 14

-Transcription takes place in the nucleus - DNA is used as a template to make a molecule of messenger RNA (mRNA) ``` Process of transcription 3 stages: 1. Initiation 2. Elongation 3. Termination ```

Answer 15

- Transcription begins when the enzyme **RNA polymerase** binds to a region of a gene called the **promoter sequence** * This signals the DNA to unwind [dNA helicase breaks H bonds] so the enzyme can “read” the bases of DNA ``` -strand used as template = template/antisense strand -The sequence of bases on the opposite strand of DNA = non-coding / sense strand ```

Answer 16

- Once the DNA has opened + RNA polymerase has attached = **RNA polymerase** moves along the DNA = **adding RNA nucleotides** to the growing mRNA strand. * The template strand of DNA is used as to create mRNA through complementary base pairing - chain, which grows from 5’ to 3’. - RNA transcription has the same information as a non-template strand of DNA by copying the information, but it consists of the base **uracil** (U) instead of thymine (T)

Answer 17

- Once RNA polymerase reaches terminator = signals the RNA polymer to stop + release from DNA - the mRNA strand is complete + detaches from DNA (the 2 DNA strands then recoil + form double helix again) - pre-mRNA released * The result is a strand of mRNA that is nearly identical to the coding strand DNA – only difference = DNA uses base thymine + mRNA uses uracil in the place of thymine

Answer 18

- In eukaryotes, the new mRNA is not yet ready for translation = called pre-mRNA + must go through more processing before it leaves the nucleus as mature mRNA - Non-coding regions of DNA = **introns** = regions that don't code for the protein. The remaining mRNA consists only of regions called **exons** = do code for the protein. - **Splicing** removes introns from mRNA + then leaves nucleus

Answer 19

- The molecule of mRNA that leaves the nucleus then travels to a ribosome in the cytoplasm, where translation occurs RNA → Protein - Activation energy from ATP used to combine tRNA with amino acid molecules (20 types of tRNA) - The genetic code within the mRNA is “decoded” to build a protein that contains a specific series of amino acids

Answer 20

The process of DNA Translation is completed in three stages: 1. Initiation 2. Elongation 3. Termination

Answer 21

- For translation to begin, the start codon (AUG) must be recognised - AUG is specific to the amino acid methionine - At the 5’ cap of mRNA, the small subunit of the ribosome binds - Subsequently, the larger subunit binds to complete the initiation complex

Answer 22

- The ribosome has two tRNA binding sites: 1. P site which holds the peptide chain 2. A site which accepts the tRNA - Methionine moves from the P site to the A site to bond to a new amino acid there = starting the growth of the peptide. - tRNA molecule in the P site no longer has an attached amino acid = leaves ribosome via the E site - The ribosome translocates along the mRNA molecule to next codon - The growing peptide lies at the P site freeing the A site for the binding of the next aminoacyl-tRNA - The cycle continues

Answer 23

1. **P Site** (Peptidyl Site) - Holds the tRNA carrying the growing polypeptide chain. - This is where the peptide bond forms between the amino acids - The first tRNA carrying methionine (AUG start codon) always starts in the P site. 2. **A Site** (Aminoacyl Site) - Entry site for the next tRNA carrying an amino acid. - The tRNA in this site matches its anticodon to the mRNA codon. - The ribosome then transfers the growing peptide chain from the P site tRNA to the new amino acid in the A site. 3. **E Site** (Exit Site) - Where the empty tRNA exits the ribosome after it has passed on the polypeptide

Answer 24

- One of the three stop codons enters the A site [UAA, UAG, UGA] - No tRNA molecules bind to these codons, so the peptide + tRNA in the P site become hydrolysed = releasing the polypeptide into the cytoplasm - The small + large subunits of the ribosome then dissociate, ready for the next round of translation

Answer 25

**Tissue** - A group of cells that are similar in structure + perform a specific function - Organized into categories based on structural + functional similarities - Tissue types work together to contribute to the overall health + maintenance of the human body

Answer 26

1. **Epithelial** - covering or lining tissue = form a protective barrier around organs + can also be involved in secretion 2. **Connective** - responsible for connecting, supporting + binding other tissues + organs together - can form many diverse types + roles depending on the contents of the surrounding matrix + the cells within 3. **Muscle** - are responsible for movement 4. **Nervous** - are responsible for transmitting signals - Each of these tissue types can differ based on the requirements of the organ they are part of

Answer 27

* Numerous – continuous rate of cell division * In close apposition to each other – little space between cells * Tightly held together by junctions * Avascular – no blood vessels between cells

Answer 28

* Covers internal + external surfaces of your body * Found in organs * Lines body cavities + hollow organs * Major tissue in glands * Structures + functions depending on where it is in the body

Answer 29

* The outer layer of your skin (epidermis) * The lining of your intestines * The lining of your respiratory tract * The lining of your abdominal cavity * Your sweat glands

Answer 30

1. Protection 2. Absorption 3. Secretion 4. Filtration 5. Sensory 6. Excretion

Answer 31

1. **Protection** - protect several aspects on or within the body - EG, the skin- protects the tissues deeper in your body, such as blood vessels, muscle + internal organs 2. **Absorption** - allow the absorption of substances - EG the internal epithelial lining of your intestines- absorbs nutrients from the food you eat 3. **Secretion** - EG the glandular epithelium- secrete (release) enzymes, hormones + fluids

Answer 32

4. **Filtration** - - The epithelium of your respiratory tract filters out dirt + particles + cleans the air that you breathe in - EG the epithelial tissue in your kidneys filters your blood 5. **Sensory** - nerve endings that are embedded in epithelial tissue allow the body to receive outside sensory stimuli * EG the stereocilia on the surface of the epithelial tissue in the ear essential for hearing + balance * EG taste buds are embedded in the epithelium of the tongue 6. **Excretion** - removal of waste from the body * EG the epithelial tissue in the kidneys excrete waste * EG the epithelial tissue in sweat glands excrete sweat

Answer 33

- **Simple tissue**: has only 1 layer of cells that are in direct contact with the basement membrane [squamous/pavement, columnar, ciliated, glandular] - **Stratified tissue**: has many layers stacked on top of each other [stratified, glandular, cuboidal] - both have nucleus, cytoplasm, basement membrane, free surface (aka apical surface = surface facing external environment)

Answer 34

- Squamous epithelial cells are **flat** + sheet-like in appearance - Line surfaces that require a **smooth flow** of fluid (blood vessels) - Line very **thin surfaces** for molecules to pass through (lung air sacs) *EG* - Inner lining of Alveoli in the lungs, glomerular capsule in the kidneys, blood vessels, lymphatic vessels, the heart - thin = speed up gas exchange in the lungs | EG given in class: Alveoli in lungs

Answer 35

* Simple cuboidal epithelial cells are **cube**like in appearance = have equal width, height + depth *EG* - Inner lining of some kidney tubules + ducts * Secretory function - eg in the thyroid * Absorptive function - Collecting ducts of the kidney]

Answer 36

* **Column**-like appearance - they are **taller** than they are wide * Found in places that secrete mucus (stomach) * Often specialised for absorption - usually has apical **cilia** or **microvilli** * can be **ciliated** - respiratory system EG * Inner lining of the majority of the digestive tract * Inner lining of ducts * Lower respiratory tract * Female reproductive system | EG given in class: Intestines

Answer 37

* Epithelial tissue involved in the production + release of **secretory products** [sweat, Saliva, Breast milk, Digestive enzymes, Hormones] * Arranged into **glands** * Glands can be classified as exocrine or endocrine depending on presence / absence of ducts **Endocrine** - internal secretion - no ducts - Release secretory products, hormones, into nearby blood vessels = to travel to other parts of body - Pituitary gland, Thyroid gland, Adrenal glands **Exocrine** - external secretion - glands with ducts - Release secretory products into a duct which opens into a specific part of the body (eg skin, stomach, respiratory tract) - Sweat glands, Salivary glands, Lacrimal (tear) glands

Answer 38

* Consist of **several layer** of cells * One layer is in direct contact with the basement membrane * One layer of cells has the apical surface exposed to the lumen of the organ / the external environment * Have a **protective role** ...The extent of friction / abrasion often determines number of layers of cells *EG* * outer skin layer - epidermis: Protection against microorganisms + water loss

Answer 39

- selective breeding of crops + animals - Artificial selection - Use of microorganisms for food production + preservation (eg cheese,bread beer) | these techniques have been around for thousands of yrs

Answer 40

* Restriction enzymes = "molecular scissors" * = they **cut DNA at specific points** * More accurate name = **restriction endonuclease** * Restriction enzymes are produced by *bacteria*. * They **cut DNA at a specific base sequence** = **recognition site**

Answer 41

**Enzyme** > **Bacterial Origin** > **Recognition Site** EcoRI > E. coli > G↓AATTC _ CTTAA↑G HindIII > H. influenzae > A↓AGCTT _ TTCGA↑A BamHI > B. amyloliquefaciens > G↓GATCC _ CCTAG↑G | (Arrows (↓ + ↑) indicate where the enzyme cuts the DNA strand.)

Answer 42

- Restriction enzymes make staggered cuts in the DNA called sticky ends - Sticky ends combine with complimentary sticky ends so different pieces of DNA can be joined / spliced - DNA ligase is used to join the sticky ends of 2 pieces of DNA | Sticky ends = single strands of DNA that overhang from the other side

Answer 43

- EG isolating useful genes (eg produce insulin & growth hormone) + place the gene into another organism - Transfer gene into animals, so that they produce special proteins in their milk. [ **Involves the transfer of fragments of DNA from 1 organism/species into another organism/species = becomes a genetically modified organism (GMO) = contains the recombinant DNA**] How? 1. Isolate gene from human cell 2. Use restriction enzymes to cut DNA on either side of useful gene 3. Isolate a plasmid from a bacterial cell—cut it with same restriction enzyme 4. Splice human gene into plasmid using DNA ligase 5. Treat bacterium so it takes up recombinant plasmid 6. Bacterium multiplies & product of gene can be used

Answer 44

A genetic engineering technique that treats diseases by introducing a functional gene into cells that have a faulty gene EG Treating genetic diseases such as cystic fibrosis. METHODS OF GENE THERAPY: - Normal allele inserted into genome - Normal allele swapped with a faulty allele - Faulty allele can be repaired - Degree to which an allele can be turned on/off can be changed

Answer 45

- Insert gene into a **virus** + use virus to insert the gene into human cells, eg herpes simplex virus. - **Liposomes** – non-virus – this is a lipid sphere that blends with cell membrane & drops allele into the cell

Answer 46

- monarch butterfly can be found in very, very large numbers - the monarch butterfly is migratory, flying huge distances every year - Monarch butterflies have larvae or caterpillars that feed on milkweed plants - there are a lot of different species of milkweed, but the genus is Asclepias.

Answer 47

* - Bt + the Monarch Butterfly - Bt = Bacillus thuringiensis [biological pesticide bacteria] - Population west of Rocky Mountain has declined > 50% since 1997 - Population east of Rocky Mountain has declined by 90% since 1995 - One billion monarchs have vanished since 1990 - Linked to herbicide use in herbicide-resistant GM corn + soybean which now constitute 89% & 94% of these crops in USA. Herbicide kills the milkweed (glyphosphate resistant GM corn). - Loss of overwintering habitat - Larva eating pollen that contains the Bt gene → toxic | all genetic reseach has potenial for abuse=should think abt consuquences

Answer 48

``` Glyphosate [herbicide] used in farming = kill weeds in crop fields - Farmers grow genetically modified (GM) crops like corn + soybeans that R resistant to glyphosate = can spray glyphosate on their fields to kill weeds without harming their crops ``` **ENVIRONMENTAL / NAURE DEBATE**: - Milkweed naturally around farms...when farmers spray glyphosate to kill weeds = milkweed gets destroyed too. - No milkweed = Monarch caterpillars have nowhere to grow = fewer butterflies. - =Glyphosate-resistant crops lead to more glyphosate use = leads to less milkweed = causes declining Monarch butterfly populations - Glyphosate use is bad for monarchs = We should protect milkweed habitats + reduce chemical use **AGRICULTURE INDUSTRY DEBATE**: - GM crops help produce more food efficiently - There’s no strong direct proof that glyphosate alone is the main cause of monarch decline (climate change + habitat loss might also play roles)

Answer 49

**Collagen** - protein, non-stretchy, white fibres - protein that makes up connective tissue - Provides structural support + tensile strength to tissues - =Prevents tissues from tearing or separating -Found in tendons, ligaments, and bones **Elastin** - Protein, stretchy, yellow fibres - Provides elasticity to tissues - =Allows tissues to stretch + recoil without damage - Found in the lungs, urinary bladder + skin

Answer 50

**Collagen tissue** - white fibrous tissue - Type of connective tissues that contain a high amount of collagen - such as tendons, ligaments, and cartilage. - Tissue that connects other tissues, such as skin, muscles, tendons, and cartilage + contains collagen as a major component - Collagen in glycoprotein matrix - EG: Tendons -mostly made of white fibrous tissue + connect muscles to bones + rely on strong collagen fiber **Elastic tissue** - yellow elastic tissues + elastin + contain glycoprotein matrix - Made up of collagen and elastin fibers - Provides elasticity + mechanical strength to tissues - Found in the skin, lungs + urinary bladder - In structures that need to return to original shape after stretching: elastic ligaments, skin, blood vessel walls + lung tissue. - EG: some ligaments (like ligamentum nuchae [neck] + flavum [spine]) are elastic, but most are collagen-based

Answer 51

**areolar tissue** - loose connective tissue that provides support + cushioning to various organs + tissues in the body **adipose tissue** - large tissues full of fat - energy store + thermal insulation to maintain body temp + acts as cushioning to protect organs - (full of adipocytes = fat cells) - Found under the skin, around organs (eg kidneys, heart) + In the bone marrow + breasts. **Brown Adipose Tissue** (brown fat) = type of adipose fat tissue invovled in heat production (thermogenesis) **White Adipose Tissue** mainly stores energy

Answer 52

BE ABLE TO DRAW IT Areolar tissue is wrapped around organs especially where blood vessels + nerves enter the organs - contains macrophage (phagocytosis + defence) - Fat cells - energy store + insulation - Elastin - strong + stretchy - Mast cells - secrete matrix - Matrix - Collagen - strong, non-stretchy - Fibroblast - secretes fibres

Answer 53

**Tendons** - muscle to bone (archilles tendons - connects the calf muscles to the heel bone) tibula/ fibula **Ligaments** - bone to bone (around knee)

Answer 54

**Skull** – Protects the brain **Clavicle** (collarbone) – Connects the arm to the body **Scapula** (shoulder blade) – Important for shoulder movement **Sternum** (breastbone) – Protects the heart + lungs **Ribs** – Protect the thoracic organs **Humerus** – Upper arm bone **Radius** – One of the forearm bones (thumb side) **Ulna** – The other forearm bone (pinky side) **Pelvis** – Supports the lower body and protects organs **Femur** – Thigh bone, the longest and strongest bone **Patella** (kneecap) – Protects the knee joint **Tibia** – The larger shin bone **Fibula** – The smaller shin bone **Carpals** – Wrist bones **Metacarpals** – Hand bones **Phalanges** – Finger and toe bones **Tarsals** – Ankle bones **Metatarsals** – Foot bones

Answer 55

- **7 cervical vertebrae** - **12 dorsal** or **thoracic vertebrae** - **5 lumbar vertebrae** - sacrum of **5 sacral vertebrae** - coccyx of **4 coccygeal vertebrae** ``` on opposite side of these labelles vertebraes on diagram of vertebral column there are... cervical curvature, thoracic curvature, lumbar curvature, sacral curvature ```

Answer 56

**Bone in Heat:** - Heat burns away the organic parts (like collagen), leaving only minerals (mostly calcium phosphate) - Bone becomes brittle, lighter + weaker - process called calcination **Bone in Acid:** - Acid dissolves the minerals (calcium phosphate), leaving mostly collagen - Bone becomes flexible, soft + weaker

Answer 57

- found in compact bones - the **structural unit of compact bone** Components: **Haversian canal:** A central canal containing arteries, veins, nerves, lymph ducts **Lamellae:** Concentric layers of bone matrix around the Haversian canal **Lacunae:** Small spaces between lamellae that contain osteocytes (bone cell) **Osteocytes:** Bone cells that maintain the bone matrix **Canaliculi:** Tiny channels that connect lacunae, allowing osteocytes to communicate + exchange nutrients

Answer 58

**osteocytes** [bone cell] - Live in lacunae (small spaces between lamellae) - Extend tiny "arms" = `canaliculi`, which are little channels used for communication + nutrient exchange - Maintain bone tissue and are connected to each other + the central Haversian canal by tiny canaliculi channels

Answer 59

**osteoblasts** - specialized bone cells responsible for the formation of bone tissue Produce + secrete bone matrix, which consists of: - `Collagen fibers` → give bones flexibility + strength. - `Mineral salts` (mainly calcium phosphate) → give bones hardness - calcium makes bones hard + can be used for milk production in women - The matrix hardens (calcifies) to form new bone. [Once octeoblasts get trapped inside the hardened matrix, they become osteocytes]

Answer 60

- bone has blood vessels through it which means that a fracture can cause major blood loss - improvised explosive devices smash limbs so badly that the only way to control the blood loss is relatively quick amputation

Answer 61

**Epiphysis** (proximal and distal): ENDS OF BONE - The rounded ends of the bone, where it articulates with other bones at the joint - Contains spongy bone (also called cancellous bone) + is filled with bone marrow. **Diaphysis**: LONG MIDDLE OF BONE - The long, central shaft part of the bone - Contains compact bone on the outer layer + a central cavity (the medullary cavity) filled with bone marrow ... - articular or hyaline cartilage - Trabeculae (thin,flat layers of bones) - Spongy bone (support + also RBC production) - Red bone marrow - blood cell prduction - Compact bone - Yellow marrow - Periosteum - Trabeculae - articular or hyaline cartilage | Femur links to hip breakages in older people

Answer 62

- **Small, needle-like structures** that make up the **spongy bone** (cancellous bone) - Trabeculae form a network of **thin, interconnecting rods or plates**, creating a **lattice-like structure** within spongy bone - They help to make the **bone lighter** while still providing strength + support - The spaces between trabeculae are filled with bone marrow (red marrow in spongy bone), where blood cell production occurs

Answer 63

A bone disease that occurs when the body breaks down more bone than it replaces = makes bones weak + brittle = more likely to break = increasing the risk of fractures bone resorption (breakdown of bone tissue by osteoclasts) outpaces bone formation (by osteoblasts), leading to a decrease in bone density

Answer 64

**Age**: The risk increases as you get older **Gender**: Women more likely to develop osteoporosis, especially after menopause due to lower estrogen levels [estrogen plays crucial role in maintaining healthy bone density + structure] **Lifestyle**: Lack of physical activity, poor diet (low in calcium + vitamin D) smoking + excessive alcohol use **Genetics**: Family history of osteoporosis increases risk *Symptoms*: no symptoms until a bone breaks - Common fractures occur in the spine, hip + wrists

Answer 65

- treatment used to relieve symptoms of menopause by replacing hormones that the body no longer produce - provides estrogen + sometimes progesterone to help manage menopause symptoms (hot flashes, night sweats) - **Helps prevent osteoporosis (bone loss) in postmenopausal women** as increases eostrogen levels

Answer 66

- A surgical procedure in which a damaged or worn-out hip joint is replaced with an artificial joint (prosthesis) - Relieves pain + improve function in people with hip joint problems, typically caused by arthritis, fractures, or other joint disorders

Answer 67

Simple falls landing badly can transmit impact up spine causing fracture of skull - When you fall, the impact from landing can travel through the body, along the spine - Thee force can travel up the spine to the head, potentially causing a skull fracture or injury to the brain

Answer 68

- Type of connective tissue that provides support + flexibility in various parts of the body **Structure**: - most common type of cartilage + has smooth, glassy appearance - Made up of chondroblasts / chondrocytes (cartilage cells) embedded in a gel-like matrix of collagen + proteoglycans - chondroblasts secrete matrix (chondrin) - No Blood Vessels / Nerves - Relies on synovial fluid for nutrient supply + waste removal = slow to heal **Function**: - Provides Support - Reduces Friction: Covers the ends of bones in joints minimizing wear + tear - Assists in Growth: Forms the embryonic skeleton + template for bone development | covers the end of femur bone + ends of bones in synovial joints

Answer 69

In joints, hyaline cartilage is known as articular cartilage + plays role in smooth joint movement - **Reduces Friction**: Provides a smooth, slippery surface for bones to glide over - **Absorbs Shock**: Helps distribute loads across the joint = reducing stress on bones - **Protects Bones**: Prevents direct bone-to-bone contact = minimizing wear + tear

Answer 70

**Chondrin** (outdated term): - describe the gel-like part of the cartilage matrix - responsible for cartilage's flexibility + support - part of the overall extracellular matrix **Chondroblasts** - Immature cartilage cells - produce + secrete the extracellular matrix (ECM) of cartilage - The matrix they secrete contains: Collagen fibers for strength, Proteoglycan +Glycoproteins

Answer 71

Inflammation of the joints, causing pain, swelling, and stiffness 2 types 1. *Osteoarthritis*. Cause: **Wear + tear on cartilage** due to **aging** 2. *Rheumatoid Arthritis*. Cause: Autoimmune disease where the **immune system attacks joint lining**

Answer 72

**Function:** Flexible support for structures that need shape retention and flexibility **Elastic Fibers:** Provides flexibility and cartilage can returns to shape after stretching **Color:** Yellowish due to elastic fibers **Chondrocytes:** Cells found in lacunae **Locations:** External ear, epiglottis, Eustachian tube

Answer 73

**Function:** Shock absorption + tensile strength for areas under heavy stress. **Collagen Fibers:** Dense collagen fibers provide strength + resistance to compression **Chondrocytes:** Fewer cells in lacunae compared to other types **Locations:** Intervertebral discs, pubic symphysis, menisci, temporomandibular joint. | Cartilage + bones are also types of connective tissue

Answer 74

1. Visceral / **smooth** / **involuntary** muscle 2. Skeletal / striated / **voluntary** muscle 3. **Cardiac** muscle

Answer 75

**Structure**: - Spindle-shaped cells with a `single nucleus` + no striations + has `elastin` **Control**: Involuntary (controlled automatically) **Location**: - Walls of internal organs (eg stomach, intestines, blood vessels) **Function**: - Involved in peristalsis, control of blood pressure, distribution of blood flow, blood pressure, vasoconstriction + vasodilation - Controls the movement of substances within organs (eg food through digestive system, blood through vessels) **Example**: - Digestive system - Stomach, bladder blood vessels - arteries, veins

Answer 76

**Structure**: - Long, cylindrical fibers with `multiple nuclei` + visible `striations` (stripes). - `actin` - protein filament involved in muscle contraction - `myosin` - protein with myosin heads that form cross-bridges with actin + Uses ATP for contraction - `cross bridges` - for muscle contraction [form between actin + myosin heads within sacromere] - `Sarcomere` - basic unit of a muscle fiber Made up of actin + myosin filaments. [z-line to z-line forms 1 sacromere] **Control**: - Voluntary (controlled consciously). **Location**: - Attached to bones for movement **Function**: - Responsible for body movement, posture + generating heat. **Example**: - Biceps, quadriceps.

Answer 77

**Structure**: - `Branched` cells with a `single nucleus` and *striations*; cells joined by `intercalated plates / discs` **Control**: - Involuntary (controlled by the heart's pacemaker). **Location**: - Heart **Function**: - Pumps blood throughout the body **Example**: - Heart muscle

Answer 78

- CNS consists of brain + spinal cord 1. Stimuli detected by **Receptor** [converted to electrical impulse] 2. Impulse sent along **sensory neurone** to the **CNS** 3. **CNS** processes impulse 4. **Motor neurone** carries impulse from CNS to **effector** 5. **Effector** cause response in body | flow diagram: arrow from receptor > CNS > effector [muscle+glands]

Answer 79

- **dendrites**: Receive nerve impulses from other neurons / sensory receptors + transmit them towards the cell body - **Cell body**: Contains nucleus, which controls the cell’s activities. processes incoming signals - **axon**: Carries nerve impulses away from the cell body towards other neurons, muscles, or glands - **myelin sheath** - **node of Ranvier** - **Axon Terminal**: Sends the nerve impulse to the next neuron, muscle, or gland by releasing neurotransmitters

Answer 80

- **myelin sheath**: Fatty layer that insulates the axon + increases the speed of nerve impulse transmission - **node of Ranvier**: Small gaps between sections of the myelin sheath that allow the impulse to jump from one node to another = speeding up transmission. [1mm between each node of ranvier]

Answer 81

`Carries sensory information from receptors (eg skin, eyes, ears) to the CNS for processing.` - **long dendrites** - carry impulses from sensory receptors to the CNS - Cell body is located outside the CNS in the dorsal root ganglia. - **long axon** - often myelinated Receptor detect stimuli (like touch, heat, sound) | know diagram

Answer 82

```Relays messages between sensory + motor neurons and processes information in the CNS + forms reflex arcs``` - **Short axon** as they only transmit impulses within the CNS - Cell body + dendrites are in the CNS. - Connects sensory + motor neurons.

Answer 83

```Transmits nerve impulses from the CNS to effectors (muscles or glands) to cause a response``` - **short Dendrites** = receive signals from intermediate neurons - **Long axon** - carry impulses from cell body to muscles / glands. - Cell body is located in the CNS (spinal cord or brain). - **myelin sheath** (made by **Schwann cells**) - **Axoplasm** - the cytoplasm inside the axon of a neuron

Answer 84

- neural pathway that controls an automatic, involuntary response to a stimulu - very useful as message gets from receptor to effector quickly as possible - do not waste time thinking about what to do = involuntary action - brain only consciously aware of what is happening after mesage is sent to the muscle

Answer 85

1. **Stimulus** (heat, pain, touch) detected receptor (skin) 2. **Receptor** converts stimulus into electrical impulse 3. **Sensory Neuron** carries the impulse from the receptor to the spinal cord (CNS) 4. **Relay/intermediate Neuron** transfers impulse from sensory neuron to motor neuron [does not involve the brain] 5. **Motor Neuron** carries impulse from spinal cord to effector (muscle / gland) 6. **Effector** (muscle) responds to the impulse by contracting / moving =causing quick reaction 7. **Response** = automatically move your hand away from the hot surface (without thinking)

Answer 86

- myelin sheath acts as **electrical insulator**, preventing the electrical impulse from leaking out of the axon = helps the impulse travel more efficiently - myelin sheath has small gaps called **Nodes of Ranvier** (unmyelinated gaps). - The electrical impulse jumps from one Node of Ranvier to the next, instead of traveling continuously along the axon - =called **saltatory conduction** = significantly increases speed of nerve transmission

Answer 87

1. **Myelination of neurone** - nerve impulse trvels faster in myelinated nerve - In a myelinated neuron = impulse can travel at speeds up to 3-120 m/s - In an unmyelinated neuron, the impulse speed is much slower, around 1-3 m/s 2. **Axon diameter** - the larger the diameter = the faster the conduction 3. **Number of synapses** - more synapses = slow conduction velocity

Answer 88

1. **Potential difference** measures the difference in charge across a membrane (inside v outside axon) 2. **Resting potential** - The potential difference across the cell membrane of a neuron at rest which is around **-70 millivolts (mV)** - Nerve cells are polarised in their resting state = As a result there is a difference in the voltage across the neuron membrane, with a value of -70mV known as the resting potential

Answer 89

- Due to the **sodium - potassium pump** which moves sodium ions out of the neuron + potassium ions into the neuron - Requires energy = ATP broken into ADP + P [active transport - also called Na+K+ ATPase] - To **pump out 3 NA+** and **pump in 2 K+** (actively transported) - Because for every 3 NA+ pumped out, only 2 K+ pumped in = number of positive ions outside membrane is higher than inside - makes **inside of axon more negative** -70mV compared to outside (which is positive)

Answer 90

The temporary change in electrical potential across the membrane of an axon [+40 mV] in response to the transmission of a nerve impulse

Answer 91

1. When impulse arrives = axon membrane becomes permeable to Na+ 2. Na+ outisde is 10x more concenrated = Na+ diffuse into neuron 3. =inside the cell becomes positively charged/less negative = about +40 mV = generates action potential 4. As Na+ enters cells = K+ begin to leave (Facilitated diffusion) = start of recovery = inside of axon becomes more negative again 5. recovery = sodium-potassium pump returns voltage back to resting potential by pumping NA+ out and K+ in = resting potential equilibrium restored

Answer 92

- where 2 nerves meet - a "swelling" or thicker part of the nerve at the synapse = sometimes called synaptic knob - Know the diagram including: presynaptic membrane, mitochondria, synaptic cleft, post-synaptic membrane - synaptic vesicles contain acetylecholine = neurotransmitter molecule

Answer 93

1. **Electrical impuls**e arrives at synaptic knob 2. Impulse causes **calcium ions** to **enter** the neurone / knob from synaptic cleft 3. Ca²⁺ causes synaptic vesicles containing **acetylcholine** to move towards the pre-synaptic membrane 4. Acetylcholine is discharged into the **synaptic cleft** 5. Acetylcholine **diffuses** across the synaptic cleft + binds to receptors on postsynaptic membrane = **depolarizing** the **post-synaptic membrane** 6. **Local influx of Na⁺** into the post-synaptic membrane causes an **excitatory post-synaptic potential (EPSP)** 7. If the EPSP is large enough, then the nerve cell develops an **action potential** 8. **Acetylcholinesterase** (cholinesterase) destroys acetylcholine.

Answer 94

- where a nerve joins with a muscle 1. Impulse arrives 2. Acetylcholine discharged 3. Depolarise muscle end plate 4. if end plates potential is high enough = an action potential is fired into muscle = contracts | learn drawing of this

Answer 95

1. **Atropine** - stops post synaptic membrane depolarising = [Blocks acetylcholine receptors] blocks action of acetylcholine = preventing nerve impulses from affecting muscles / glands 2. **Eserine** - prevents acetylcholinesterase from destroying acetylcholine 3. **Strychine** - enhances synaptic transmission causing convulsion (rapid involuntary muscle contractions) 4. **Curare** = South American Indian arrow poison, works in similiar way to atropine - Blocks nicotinic acetylcholine receptors on muscle cells = preventing acetylcholine from binding + triggering muscle contractions

Teaching block 2 [1] Flashcards

(119 cards)