Lab Final Flashcards

Question

Sensory pathway basic functions

Answer 1

1. Sensory recognition: capture a form of energy (stimulus) that leads to a graded potential in receptor cells → Sensation: being aware of a stimulus 2. Transduction: converting the graded receptor potential into an action potential → basically, sensation is now transduced into a nerve impulse 3. Transmission: action potential travels to the central nervous system (brain and spinal cord) 4. Perception: interneurons provide the meaning of the stimulus → brain builds perception of the taste / molecular structure (can also extend to hearing, seeing, etc) Overall: detection and processing of sensory information allows for generation of motor responses, which is the physiological basis of animal behavior.

Answer 2

1. Ionotropic receptors: ion channel in the taste cell membrane that allow ions to flow into the cell via depolarization (opening voltage-gated Na+ in / K+ out / Ca2+ in channels in the ER membrane to open), changing the internal pH and composition of the cell → allows you to perceive sour and salty - - Sour = more H+ inside, lower pH - - Salty = more Na+ inside, therefore more positive inside the cell 2. Increased cytoplasmic [Ca2+] mobilized synaptic vesicles to fuse with cell membrane and release neurotransmitters into synaptic cleft btwn taste receptor and afferent sensory neuron 3. Once signal exceeds threshold in postsynaptic sensory neuron, action potential will travel to the gustatory centers of the brain - - More salt = more gates opened = more fusing of synaptic vesicles to cell membrane = more release of neurotransmitters = brain can tell btwn high and low salt content of the food

Answer 3

Umami: reflect the flavor of amino acids GTP: important in translation; energy rich molecule that is not as widely used as ATP -- GDP acts as a switch; if nothing is attached, then considered off → if umami attaches, then GDP released as GTP Pathway: Use metabotropic receptors; membrane bound → GPCR, largest family of receptors; membrane bound; all members have 7 transmembrane helices 1. Taste substances bind to cytoplasmic domain → GPCR changes shape, triggering a response for the intracellular G protein to activate an effector molecule → increases [secondary messenger], thus single transduction signal amplified - - FOR SWEET: activated G protein gustducin activates adenylate cyclase → adenylate cyclase catalyzes conversion of ATP to cAMP → cAMP activates protein kinase that phosphorylate and closes K+ channel → depolarization causes Ca2+ channels in ER membrane to open - - FOR BITTER: activated G protein transducin activates phospholipase C (PLC) → PLC catalyzes conversions of PIP2 into secondary messenger IP3 → IP3 binds to Ca2+ channels in ER membrane, opening them 2. Influx of Ca2+ ions into cytoplasm mobilize synaptic vesicles to migrate to PM and release neurotransmitters, which trigger AP in afferent sensory neurons

Answer 4

Blue dye: allows for visualization of the quantity of papillae density bc density can affect taste sensitivity→ bumps without taste buds will stain blue; bumps with taste buds will stain light blue Agonist: bind to receptor and mediate the typical ligand receptor response; promoter Antagonist: bind to the receptor and lessen / block the typical ligand receptor response; blocker Gymnema: brown liquid; herb from India used to treat diabetes; antagonist for sweet receptors, specifically T1R2 and T1R3 Miraculin: aka M-berry; protein extracted from a West African fruit; @ neutral pH, antagonist for sweet; @ acidic pH, antagonist for sour, agonist for sweet

Answer 5

PTC genetics: aka phenylthiocarbamide; coupled with the taste receptor TAS2R38 due of the bitter taste modality compounds with N-C=S moiety (part / functional group of a molecule) Haplotype: particular set of genetic variations that are inherited together on one chromosome → most common: PAV are tasters (dominant), AVI are non tasters (recessive); heterozygotes were intermediate tasters; inherited in a Mendelian fashion - - SNP: single nucleotide polymorphism; - - Lesser common (intermediates) PVI, AAI, AAV activated 40% when compared to PAV → may be caused by membrane targeting or impaired coupling of receptor with signal transduction G proteins Presence of Thymine @ position 785 of AVI prevents restriction Fnu4H1 from curring, thus the DNA remains intact as a 303 bp fragment; presence of Cytosine @ position 785 is the correct (think: C = correct) sequence for cutting and subsequent digestion of the PCR product, yielding 2 DNA fragments of 238 and 64 np. Presence of Alanine @ position 49 and Valine @ position 262 diminishes receptor function but variation @ position 296 had little effect PROP vs PTC: test proxy for PTC BUT not interchangeable; however, will be similar at low concentrations; former not as reliable because sensitivity can fluctuate due to genome of individual -- All alleles are expressed, therefore PTC insensibility must be due PTC not activating AVI (as opposed to not expressing the allele to not sense PTC) Tasters good for rejecting possible poisons and therefore surviving (ie dislike smoking); non tasters good for being able to eat a larger range of compounds unbothered (ie can eat broccoli BUT over ingestion of isothiocyanates can lead to thyroid disease and goiter)

Answer 6

During exercise, actively contracting muscles requires lots of ATP BUT have limited ATP stores Phosphagen: creatine phosphate (in skeletal muscle) that can be converted into ADP (see manual) -- Together, creatine phosphate and stored ATP allow for prolonged excercise outside of aerobic capacity Vigorously contracting muscles COMPRESS blood vessels, impairing blood flow and therefore oxygen exchange. Thus, ANAEROBIC processes provide additional ATP, which can prolong muscle action for about one minute. - - Glycolysis (anaerobic) is 2.5x faster BUT is more inefficient than full blown aerobic resp (ie glycolysis > kreb > oxidative phos) → 2.5 ATP yield versus original XX amount - - Anaerobic ATP production causes accumulation of lactic acid, contributing to muscle soreness

Answer 7

Prolonged activities are powered aerobically → when full engaged (within 15 min), O2 is delivered to contracting muscles by combined actions of the cardiovascular and respiratory systems Mitochondria use the O2 as a final electron acceptor, which generates the highest yield of ATP (~32 ATP / glucose) Increased energy expenditures -- Both intrinsic and extrinsic factors can improve CO and ventilation rates Arterioles (remember vasoconstriction and vasodilation) actively contracting muscles vasodilate in response to local chemical conditions (ie decreased [O2], pH and increased [H+], NO (nitric oxide), and prostaglandins) Sympathetic nervous stimulation induces widespread vasoconstriction of arterioles to minimize blood flow to areas that can wait → want to increase stroke volume in the areas that are currently working (ie not digestive viscera and skin) Total peripheral resistance: something about increasing blood viscosity / pressure as a result of vasoconstriction

Answer 8

1. Pulmonary and systemic circuits are in series, therefore both must pump equal volumes of blood BUT pulmonary is a LOW PRESSURE circuit (bc goes to lungs; keeps them dry) - - Pulmonary edema is dangerous bc gas will diffuse 200x more slowly if there is too much liquid → gas exchange will almost stop and you’ll basically suffocate to death 2. Human heart is MYOGENIC → electrical impulses originates in specialized conducting cells - - SA Node: aka pacemaker; has the fastest rate of depolarization 3. Impulses from SA node will spread through conducting fibers and from cell-to-cell through gap junctions 4. Depolarization from SA node spreads throughout the atrea, pumping blood into ventricles 5. Impulse arrives at AV node, pauses (allows atria to empty itself of blood before the ventricles contract) and then spreads to the ventricles via Bundle of His and Perkinje fibers.

Answer 9

Measures electric current through the heart → waves go P / QRS / T P wave: 0.8 seconds -- caused by spread of impulse through the atria; approximately 0.1sec after P wave, the atria will contract Expelling of blood from the atria prior to ventricular systole (contrast to atrial systole) QRS complex: results from rapid ventricular depolarization (0.08 sec) and precedes ventricular contraction; complicated shape results because the path of impulse waves changes continuously through ventricular (ie moves down AV node and then changes directions as weak signals move through interstitial fluid) → Bundle of His and Purkinje fibers Overwhelms repolarization of atria T wave: caused by ventricular repolarization (0.16 sec) → repolarization slower than depolarization, therefore T wave is more spread out

Answer 10

CO = HR (bpm) * SV (ml/beat) = Total blood volume passes through each side of the heart each minute During exercise, CO can increase 4-5x in non athletes (20-25 ml/min) ; 7x in athletes (35 ml/min) ; 10x when skeletal muscles as arterioles vasoconstriction blood flow to non targets HR influenced by intrinsic and extrinsic factors - - Intrinsic: SA node sets pace; increases when atria stretched during venous return → think about the volume of blood that is returning to your heart. During exercise, the skeletal muscles are pushing large amounts of blood back, which will stretch the atria - - Extrinsic: sympathetic stimulation of SA node by norepinephrine, epinephrine, thyroxine SV influenced also by intrinsic and extrinsic factors - - Intrinsic: stretching of cardiac muscles increases force of contraction (Frank-Starling law) - - Extrinsic: sympathetic innervation of cardiac muscles increases contractility

Answer 11

Systolic blood pressure: larger number; determined by how strongly the left ventricle contracts during systole Diastolic blood pressure: lower number; determined by the “stretchiness” of the aorta and large arteries that sustain the arterial pressure during diastole Mean arterial pressure (MAP) has about one third difference between systolic and diastolic pressures (ie ventricular systole has a one third duration of cardiac cycle) -- During exercise, MAP increases only slightly due to vasodilation of arterioles servicing active skeletal muscles, thus reducing TPR (total peripheral resistance) Biggest drop off at arterioles due to reduced diameter of arterioles (0.0037 cm) vs arteries (1.5 cm).

Answer 12

1. Blood pressure in brachial artery used to estimate systolic and diastolic blood pressure in arteries and aorta 2. Pressure cuff is inflated to obstruct blood flow through brachial artery 3. Cuff pressure is gradually lowered until it is just below systolic pressure → blood will now spurt through and turbulent blood flow (ie Korotkoff sounds) can be heard with a stethoscope - - First Korotkoff sounds indicates systolic pressure - - Korotkoff sounds disappear as cuff pressures falls below diastolic pressure Measuring ECG 1. ECG are measured for student volunteers at rest and following exercise 2. Duration (in seconds) from R peak of QRS complex to the next R peak estimates duration of a single heartbeat → duration indicates systole 3. Exercise increases heart rate, therefore increases T to P and decreases R to R → BUT P to T is fairly consistent

Answer 13

1. Inhale O2 rich air 2. O2 rich blood carried from lungs to body 3. Exercising muscles use O2 and ATP, producing CO2 4. CO2 enriched (O2 depleted) blood returns to the heart 5. O2 poor air returns to lungs 6. Exhale CO2

Answer 14

Calculation of Cardiac Output CO = HR * SV -- Both left and right ventricles pump nearly identical volumes at the same rate Calculation of Mean Arterial Pressure MAP = CO * TPR = ⅓ (Ps - Pd) + Pd → TPR = MAP / CO Calculation of SV from pulse pressure SV = 1.7 (Ps and Pd) -- Close linear relationship Calculation of heart rate: HR = 60 * 1 / (RR time interval) Calculation of TPR (total peripheral resistance) TPR = MAP / CO -- Yield estimation of overall constriction or dilation of arterioles leading to tissues and organs of the systemic circulation Calculation of lung ventilation rate Lung ventilation = TV * breathing rate -- During excercise, TV and BR increase while IRV and ERV decrease Calculation of vital capacity VC = TV + IRV + ERV

Answer 15

Electrocardiogram: measures electrical currents going through the heart via surface electrodes that are placed on the skin Cardiac output: determinant of cardiovascular function; expected to increase with exercise due to increased HR and SV Heart rate: number of times the blood is pumped out per minute Stroke volume: volume of blood pumped out during each beat TPR (total peripheral resistance): controlled by changing the size of systemic arterioles; the more dilated, the less resistance

Answer 16

Tidal volume: volume of air that you breath in and out during normal breathing Inspiratory reserve volumes (IRV): maximum volume attained during forced inhalation Expiratory reserve volumes (ERV): maximum volume exhaled during forced exhalation Vital Capacity: total volume of air that can be expired after a maximum inspiration Residual Volume: small volume of air remaining in the lungs after the maximum expiration; used to keep the lungs open

Answer 17

Sympathetic nervous system: “fight or flight” system Activated during exercise to release norepinephrine and epinephrine (aka adrenaline) onto the sinoatrial node (pacemaker), inducing the sending of impulses more often, which increases the heart rate → more blood is thus sent to the ventricular cardiac muscle Cause vasoconstriction (arterioles constrict), decreasing blood flow to parts of the body that are not exercising ;; causes vasodilation (arterioles expand), increasing blood flow to parts of the body that are exercising Negative control feedback: controlled variable is sensed by the nerves; medulla oblongata (brain stem) receives signals; activate sympathetic nerves to the heart and blood vessels, in addition to nerves to the respiratory muscles to alter their activities → may have positive too?

Answer 18

1. PTC Taster genes code for a GPCR membrane bound receptor (chromosome 7) which responds to compounds with N-C=S 2. Within coding region are three SNPs (inherited together to form HAPLOTYPE) - - SNPs: single nucleotide polymorphism; point mutation (substitution) - - When inherited together produce the NON TASTER haplotype known as AVI (three amino acids of a non taster; Ala-Val-Iso) → taster allele is known as PAV (Pro-Ala-Val) 3. PCR Primers designed to amplify a 303 bp amplicon containing the 2nd SNP can be used to genotype the allele following restriction digestion using Fnu4H1 - - Cloning of a piece of DNA that has at least one SNP via PCR → lets you know whether individual is heterozygous or homozygous recessive - - Restriction digestion: bacterial immunity; can cut foreign DNA at recognition sequence 4. 2nd SNP @ position 785 is located within a recognition sequence of the restriction endonuclease Fnu451 → will be cut if you’re a taster (if not cut, then non taster) - - Sequence in question → 5’ - GXNGC - 3’ where X is the SNP - - Presence of Thymine @ position 785 of AVI prevents restriction Fnu4H1 from curring, thus the DNA remains intact as a 303 bp fragment - - Presence of Cytosine @ position 785 is the correct (think: C = correct) sequence for cutting and subsequent digestion of the PCR product, yielding 2 DNA fragments of 238 and 64 np.

Answer 19

HEK293 cells transfected with PAC and AVI alleles (DNA) Transfection: introduction of foreign gene into eukaryotic cell → contrast to transformation, introduction into bacterial cell (plasmids) 1. Receptors then expressed in cell membrane of human embryonic kidney cells, genetically engineered cells that are working appropriately. 2. Monitor via Fluo-4 Calcium Indicator → binding of calcium to Fluo4, which fluoresces (you can measure this, therefore quantitative) -- Contrast to psycho genomic testing 1. Extract DNA of the individual you want to test 2. Perform restriction analysis (aka DNA fragmentation) to identify genotype 3. Provide individuals with the substance and they give their responses (more qualitative)

Answer 20

Reverse Transcriptase - PCR 1. mRNA extracted from human tongue tissue and amplified using RT-PCR to create cDNA - - Reverse transcriptase: RNA back into DNA; enzyme that retroviruses; yields complementary DNA strands - - mRNA extraction is super easy → wash with a poly U tail to catch mRNAs with long poly A tails (aka affinity chromatography) - - Extension of 3’ end to create a duplex (something) to yield cDNA yield 2. Levels of mRNA were determined using quantitative RT-PCR - - Lots of variability but want to measure expression → quantify how much cDNA was produced from different individuals - - Use TAQMAN PROBE: located in middle of amplicon, complementary to part of the template sequence; proportional to copy number of mRNA; has a fluorescent dye attached to it - ---- Has a quencher at the 3’ end -- probes lack OH at 3’ end → any fluorescence while the probe is intact will be absorbed by the quencher - ---- Standards of known concentrations of cDNA generate standard curve to which fluorescence of unknown sample is compared - - Exonuclease: happens 3’ to 5’ ; degrades nucleotides starting at 5’ end though → degradation of probe nucleotides releases fluorescence - ---- Contrast to DNA polymerase, which happens 5’ to 3’ - ---- Proofreading: allows DNA polymerase to back up in order to correct a mistake → 3’ to 5’ direction of the DNA polymerase in the presence of TAQMAN (exonuclease) - - Threshold of detection for fluorescence → aka Ct - ---- The more DNA you start with, the sooner you will reach that threshold - ---- Can compare DNA lengths and then plot that information → [DNA] horizontal; Ct vertical → linear slope downwards 3. in situ hybridization of circumvallate taste papillae with sense and antisense cRNA (bc cRNA is double stranded) - - In situ hybridization: taking a single strand DNA probe that will bind to an mRNA for expression -- production of a spot that you can see - - Sense: same sequence as mRNA - - Antisense: complimentary to sense strand; template during transcription

Answer 21

Specifically SHORT TERM: Baroreceptors: in carotid sinuses and aortic arch send impulses to cardiovascular center in the medulla oblongata Chemoreceptors: in carotid and aorta relay information regarding [CO2] and pH to cardiovascular center in medulla Hormonal controls: epinephrine (adrenal medulla), thyroxine (thyroid gland), and norepinephrine (sympathetic stimulation) accelerate CO thus increasing blood pressure

Answer 22

Convection alternating Diffusion 1. Convective motion of air ceases inside of alveoli; due to small diameter, diffusion is sufficient for exchange of O2 and CO2 with blood - - Tidal ventilation mixes fresh air with stale air in alveoli of the lungs → 12% fresh and 88% stale 2. Alveoli made from squamous epithelium (good bc thin diffusion barrier with large SA, allowing for rapid diffusion) - - Type 1: make up bulk of membrane → has a membrane responsible for gas exchange - - Type 2: secrete the surfactant (mixture of lipids and proteins) that reduce surface tension in water (reduces the H bonding of water to reduce the heavy presence of water in the alveoli) → no water film to prevent gas exchange 3. Gases are moving down their concentration gradient (ie CO2 diffuses back into the air from the blood and then O2 enters the blood again) 4. Ventilation rate and CO are well matched → harder you breathe, the faster your heart beats

Answer 23

1. Set basic ventilation rate and respond to chemosensors in the aorta and carotid arteries - - Eupnea: basic ventilation at rest → usually 10 - 12 breaths / min but if people know they're being measured, can fluctuate - - Hyperpnea: increase of ventilation during exercise → increase by 10x to 20x 2. pH, P(CO2), and P(O2) sensors monitor blood in aorta and carotid arteries; afferent sensory input to respiratory centers in medulla - - Afferent: towards the brain - - Efferent: from the brain * * Increasing P(CO2) or falling pH (PO2 < 60 mmHG) increase ventilation 3. Exercise enhanced ventilation not prompted by rising P(CO2) or falling pH, P(O2) for two reasons: - - Ventilation increases abruptly as exercise begins - - Although venous levels change, arterial P(CO2) and P(O2) remain constant during exercise 4. Three neural factors involved - - Psychological stimuli (conscious anticipation) - - Cortical motor activation of respiratory centers in brain stem - - Excitatory impulses from proprioceptors in moving joints, muscles, and tendons

Answer 24

conserved among nearly all animals, especially early stages 1. Fertilization 2. Cleavage 3. Gastrulation: forming of three germ layers (endo, meso, ecto) 4. Neurulation (formation of a neural tube) and organ development - - Usually a result of interactions / release of chemical signals between the germ layers → Mesoderm produce neural cords to the ectoderm, which insulates it, creating the neural tube

Answer 25

based on differences in early gastrulation and fate of blastopore (or functionally equivalent structure in humans is the primitive streak) - - Proto: mostly invertebrates → “first mouth” - - Deutero: includes chordates and echinoderms → “second mouth” (anus develops first) 1. In both bilaterian groups, fertilized egg divides repeatedly via cleavage until 8 cell stage, where differences in orientation can be seen - - Proto: offset division yields spiral cleavage → if splits at this stage, will die - - Deutero: stacked division yields radial cleavage → if splits at this stage, then have twins 2. Once the dividing cells rearrange into a round hollow ball, one wall begins to indent (via gastrulation) to form a blastopore (opening) where the indented cell walls will form the gut 3. As cells migrate within the embryo, they organize into three layers: ectoderm, endoderm, and mesoderm. - - Schizocoelom: typical of proto and higher vertebrates; formed by splitting of mesoderm to form the body cavity - - Enterocoelem: typical of deutero; mesoderm formed by punching of outpocketings of the archenteron (embryonic digestive gut)

Answer 26

Marine animals: traditional way to reproduce is to eject their gametes into the water and just let them have at it; usually released in a synchronized manner (in lab, will use CaCl as trigger) 1. Swimming sperm comes in contact egg molecules in jelly coat, triggering acrosomal reaction - - Jelly coat: maintain species to species recognition 2. Acrosome releases enzymes that digest a path through jelly coat. - - Acrosome: sac at the top of sperm head; derived from the golgi → when it recognizes the proteins in the jelly coat of the egg, it will burst to release the enzymes 3. Species-species recognition btwn acrosomal process of sperm and receptor proteins on egg triggers PM (plasma membrane) fusion when the sperm-binding receptors trigger - - Vitelline layer: surrounds the outer surface of PM of ovum - - Polyspermy: fertilization by more than one sperm; lethal for an egg 4. Entry of sperm nucleus causes an influx of Na+ (more positive inside) > egg rapidly depolarizes > prevents additional sperm from binding to PM → FAST BLOCK to polyspermy via electrical barrier 5. Depolarization of egg opens Ca2+ channels in the ER > creation of fertilization envelope → SLOW BLOCK to polyspermy via physical barrier (happens in humans) - - One of the cortical enzymes is a trypsin-digesting protease that cleaves proteins attaching vitelline layer to the PM layer of the egg.

Answer 27

Taken by chemically freezing the egg and tracking the progress of the egg with a calcium flux (by using something that fluoresces when calcium is present) Ca2+ known to promote fusion of vesicles to PM; will release from ER and trigger cortical granule exocytosis and subsequent fusion with PM to begin forming fertilization envelope. Cortical granules contain enzymes (specifically, rypsin-digesting protease) that cleave proteins attached vitelline layer to the PM layer of the egg and digested particles cause osmotic swelling beneath vitelline layer; finish forming fertilization envelope as vitelline is released from PM.

Answer 28

Defined as the repeated mitotic cell division of a zygote with little or no growth; cell cycle during cleavage is Synthesis > Mitosis > S > M … → With each division, cells (called blastomeres) will become smaller Cleavage patterns reflect the amount of yolk stored in the zygote: three levels of yolk deposition 1. Microlecithal: slight amount → sea urchins, humans (primarily get nutrients from placenta) 2. Meso: moderate 3. Macro: enormous → reptiles YOLK impedes cytokinesis - - When the yolk is sparse, mitotic furrows pass successfully through entire zygote → HOLOBLASTIC CLEAVAGE (centered blastocoel) - - When yolk is plentiful, mitotic furrow is slowed, only a portion of the cytoplasm is cleaved → MEROBLASTIC CLEAVAGE (off center blastocoel)

Answer 29

Sea Urchin example: microlecithal yolk, holoblastic cleavage → blastocoel (fluid filled cavity) is centered inside the blastula Frog example: also holoblastic BUT mesolecithal yolk - - First two divisions along meridian between animal and vegetal pole; cleavage delayed in vegetal pole by mesolecithal yolk. - - During third and subsequent divisions, yolk displaces towards cleavage furrow towards animal pole, resulting in more division and smaller blastomeres near animal pole → blastocoel forms entirely in animal hemisphere

Answer 30

1. Gastrulation begins on the dorsal side (opposite where the sperm enters the egg) as cells involute over the dorsal lip into the interior, forming the blastopore - - Involusion: inward movement of an expanding outer layer of cells 2. Blastopore extends around embryo as more surface cells invaginate. - - When the ends meet, blastopore forms a circle that shrinks as ectoderm spreads downward. Continued involution expands endoderm and mesoderm inward as archenteron forms. 3. Circular blastopore (fated to become anus) surrounds a yolk-plug (remaining patch of endodermal cells on the vegetal side, created during the formation of the dorsal lip) - - Cells remaining on surface are ectoderm, endoderm is innermost, mesoderm is intermediate.

Answer 31

1. Cells from 2 or 3 germ layers interact in organ formation via induction (molecular signals that make receiving cells differentiate into a specific cell type) 2. Mesodermal notochord induces ectodermal cells thicken and flatten to form a neural plate Notochord: flexible, gelatinous rod that acted as a rudimentary spinal cord for muscle contraction / movement BUT had an inability to telescope 3. As neural plate sinks, will roll into neural tube, forming the basis of the central nervous system 4. Neural crest (vertebrates only) break lost from neural folds and ultimately migrate throughout the embryo to differentiate into different structures: a. ganglia of PNS b. hormone producing cells in the medulla c. schwann cells in the CNS d. most of the cartilage and bone of lower jaw e. odontoblasts (embryonic / immature cells that create teeth) f. pigment cells g. connective tissue and smooth muscle of heart → ultimately derived from ectoderm

Answer 32

1. Strips of mesoderm lateral to notochord separate into blocks (aka somites) 2. Mesenchyme cells dissociate from somites and migrate to form vertebrae, rib cage, parts of occipital plate of skull, skeletal muscles, cartilage, tendons, and skin of back 3. Somites reveal segmented nature of vertebrates --> the more you have, the older the organism Notochord: flexible, gelatinous rod that acted as a rudimentary spinal cord for muscle contraction / movement BUT had an inability to telescope

Answer 33

1. Due to extensive yolk deposits in eggs of reptiles, birds, and monotremes, DISCOIDAL CLEAVAGE is restricted to a cap of dividing cells at an animal pole 2. Flattened blastula is two layered: upper EPIBLAST (future embryo) and lower HYPOBLAST (future yolk sac and stalk that connects yolk to embryo), with a blastocoel in between 3. Primitive streak is functionally equivalent to blastopore; will be grey in color 4. Surface cells of epiblast migrate towards primitive streak and involute inside, forming endoderm (displaces hypoblast) and mesoderm 5. Cells remaining on surface become ectoderm

Answer 34

1. At anterior end of primitive streak is a concentration of cells known as Hensen's node 2. Cells entering the node migrate anteriorly and contribute to the developing brain 3. As development continues, primitive streak with Hensen’s node regresses posteriorly 4. Anterior to the Hensen’s node, notochord forms repeating blocks of mesoderm (somites), which reveal the segmented nature of vertebrates 5. Mesenchyme cells dissociate from somites and migrate to form vertebrae, rib cage, parts of occipital plate of skull, skeletal muscles, cartilage, tendons, and skin of back 6. Posterior to the somites, the broad neural plate occurs, followed by the Hensen’s node and the remains of the primitive streak

Answer 35

creation of sperms 2n, 2c (mitosis yields spermatogonia B ) > 2n, 4c (mitosis yields primary spermatocytes) > > 1n, 2c (meiosis 1 yields secondary spermatocytes) > > > 1n, 1c (meiosis 2 yields spermatids) Spermatogonia stem cells divide mitotically into two daughter cells A and B - - A remains at basal lamina surface as stem cell - - B cell (spermatogonia 2n, 2c) replicates becoming primary spermatocytes (2n, 4c) Cytoplasmic bridges between spermatocytes enables molecular exchange and synchronization -- In humans, the X chromosome is one of the most genetically rich ones. Uniquely X chromosomes (versus Y chromosomes), therefore have lots of X linked diseases expressed in males (ie color blindness, muscle dystrophy) ``` Sertoli cells (sustentocytes) seal around developing sperm cells (blood testis barrier; sealed with tight junctions); provide nutrients, secrete androgen / binding proteins / inhibin -- Inhibin: enzyme that travels to brain that stop testosterone production; allows for controlled production of testosterone ```

Answer 36

creation of ovum 2n, 2c (Oogonium goes through mitosis) > 2n, 4c [DNA replication then goes through meiosis 1 (stalled at prophase 1), yields primary oocyte] > > 1n, 2c [meiosis 1 (completion), yields secondary oocyte] > > > 1n, 1c [ovulation and fertilization yields fertilized egg ; meiosis 2 completed] 1. Each oogonium becomes surrounded by a single layer of squamous cells (now a PRIMORDIAL FOLLICLE) → oogonium replicates DNA and enters into meiosis 1, where it stalls at prophase 1 (now a PRIMARY OOCYTE) -- occurs before you’re born 2. About a year before its possible ovulation, surrounding squamous cells become cuboidal (now a PRIMARY FOLLICLE) and oocyte enlarges 3. At beginning of ovarian cycle, 14 to 20 primary follicles begin developing due to FSH. Follicle cells become stratified (now a SECONDARY FOLLICLE); these cells convert androgens into estradiol and provide it and nutrients to growing oocyte 4. By day 9, only one secondary follicle (usually) remains 5. LH surge on day 14 triggers primary oocyte to complete meiosis 1 (stalls at meiosis 2) becoming a secondary oocyte, soon followed by ovulation 6. Meiosis 2 completed only at fertilization

Answer 37

1. Cohort of primary follicles (each with primary oocyte stalled at prophase 1) begin to grow stimulated by FSH. 2. When >1 layer of follicle cells (granulosa cells), now called secondary follicle 3. Mid-phase, one dominant secondary follicle survives dip in [FSH] 4. Connective tissue layer forms around follicle (theca = source of androgens in response to LH); also, glycoprotein-rich layter, zona pellucida, forms around primary oocyte 5. Graafian (mature) follicle forms, and primary oocyte completes meiosis 1 (now a secondary oocyte) Ovulation: LH surge triggers expulsion of secondary oocyte from ovary Luteal Phase: ruptured follicle secretes progesterone (steroid hormone that stimulates uterus in preparation for pregnancy)

Answer 38

Trypsin inhibitor: soybean derivative; will result in partial or abnormal fertilization envelopes surrounding the sea urchin eggs Calcium ionophore: A23187; will bind to calcium ions and transport them across the cell membrane, causing an artificial influx of calcium → kickstarts formation of envelope membrane (remember the pathway?)

Answer 39

Seminiferous: location of sperm production Spermatogenic cells: production of mature sperm cells; outer cells are stem cells (least developed) and will mature as they are pushed into the lumen Spermatids (mature): immature male sex cell that lacks a flagellum → once added, will be called spermatozoa Leydig cells: aka interstitial cells; small clumps of cells lying between seminiferous tubules; produce testosterone Sertoli cells: aka sustentocytes; nourish sperm development by producing antigen binding protein for testosterone; provide fluid for sperm to migrate to epididymis; also provide testes blood barrier (keeps toxins out; nice environment)

Answer 40

Primary follicle: jacket of cells within which is a developing egg; as it develops, it secretes nutrients to the ovum; also secretes estrogen Growing follicle: diff sizes within diff stages of oogenesis Mature follicles: large follicles that bulge from the surface; contains large fluid filled area called “antrum” Zona pellucida: thick transparent membrane surrounding a mammalian ovum before implantation Ovum: mature egg Corpus luteum: large mass of cells formed from the follicle after ovulation that secretes estrogen and progesterone Granulosa cells: aka zona radiata that surround the ovum; line the antrum and secrete estrogen

Lab Final Flashcards

(64 cards)