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THE MCAT-BIO 5
GAMETOGENESIS, MENSTRUAL CYCLE, BIRTH
| Question | Answer |
|---|---|
| Why does menstrual cycle stop with menopause? | ovary is less responsive to pituitary gonadotropins and cyclic changes disappear |
| Regulative Hypotheiss | Each cx has complete info for construction of multicx organism --> dependent on cx position and environmental factors |
| Mosaic Hypothesis | parts of plans handed out to cx that need them during development |
| Does sperm ever interact with blood? | NO --> protected by blood-testes barrier |
| Where is sperm made? | seminiferous tubules |
| Where is sperm stored? | epididymis |
| What is path of sperm? | seminiferous tubules - epididymis - vas deferens - ejaculatory duct - nothing - urethra - penis |
| What does GNRH stimulate? | release of FSH and LH |
| What does the follicle house and produce? | houses oocyte and produces estrogen |
| Estrogen normally inhibits ____ but causes ____ surge when it reaches a certain threshold | LH and FSH / LH |
| What is necessary to maintain the endometrium? | progesterone (and estrogen) |
| What maintains the corpus luteum? | HcG from placenta |
| The corpus luteum goes away after the ______ trimester no matter what | first |
| What takes over the job of the c.l. and makes progesterone? | placenta |
| What does FSH stimulate in oogenesis? | primary oocyte --> secondary oocyte |
| What is one of the first signs of pregnancy? | HcG in urine |
| What causes menses? | no hx support of endometrium and it sloughs off |
| What is a baby sperm called vs. a mature sperm? | spermatogonium vs. spermatozoa |
| Where does fertilization take place? | oviduct in fallopian tubes |
| Where does the primary oocyte halt before puberty? | Meiosis I at prophase |
| Where does primary oocyte become upon completion of meiosis I? | secondary oocyte |
| What does secondary oocyte halt at before fertilization? | Meiosis II at metaphase |
| Both oogonium and spermatogonium become primary after? | puberty |
| Spermatogonia --> sperm | spermatogonia - primary - secondary - spermatid - sperm |
| What does sperm contribute to ovum? egg contribute? | -sperm = DNA only -egg = DNA + everything else |
| What is the differentiation of ovum that implants in the endometrium? | blastocyst |
| Zygote --> Blastocyst steps | zygote - morula - blasocyst |
| What prevents additional sperm from penetrating egg? | cortical reaction |
| What causes sperm to penetrate egg? | acrosomal reaction |
| What is cleavage in relation to cell growth? | mitotic divisions without cell growth |
| Blastula vs. blastocyst | -blastula = non-mammals -blastocyst = mammals |
| Morula vs. blastocyst | -morula = solid ball -blastocyst = hollowed-out ball |
| What are the basic stages of development (fertilization --> neuralation)? | fertilization, cleavage, blastula formation, gastrulation, neuralation |
| Gastrulation in mammals | cx start migrating inward at primitive streak |
| Primitive streak | where cx start migrating inwards during gasturlation |
| What is importance of gastrulation? | forms primary germ layers (endoderm, mesoderm, ectoderm) |
| How to form the brain and spinal cord during neuralation? | ectoderm folds into a tube |
| Ectoderm | skin, nerves, brain, lens of eye |
| Mesoderm | heart, muscle, skeleton, blood vessels, bone, kidney, gonads |
| Endoderm | inner lining of digestive tract and respiratory tract, guts, lungs, liver, pancreas, digestive internal organs |
| Determination | irreversible commitment to become a certain cx type |
| Differentiation | becoming a cx type and adopting its specialized fxns |
| specification | ccx is just beginnign to be committed to develop into a certain type --> reversible |
| What are the stages of commitment? | specification followed by determination |
| What causes induction? | physical touching of cells or by releasing chemicals |
| What marks certain proteins for degradation? | ubiquitin |
| What are the proteases called that act during apoptosis? | caspases |
| What is a protease? | enzyme that catalyzes protein degradation |
| Where are testes located? | scrotum |
| How long does it take to mature sperm? | 72 days |
| What contributes to seminal fluid? | seminal vesicles, prostate, bulbourethral glands |
| What provides energy to the sperm? | fructose |
| Sperm is ____ in order to survive in acidic female environment. | alkaline |
| What does midpiece have in sperm? | lots o fmito for energy |
| Primary spermatocyte are haploid / diploid while secondary are? | -diploid -haploid |
| What is a mature spermatid called? | spermatozoa |
| How does spermatozoa become activated for fertilization and where? | -vagina --> capacitation |
| What is the path for sperm starting at the vagina? | vagina - v.canal. - cervix - uterus - fallopian tubes |
| How are the testes both an exocrine and an endocrine gland? | -exocrine - seminal fluid -endocrine - androgens and peptides |
| Function of leydig cells | convert cholesterol --> testosterone |
| What effect does Testosterone have on sertoli cells? | T binds to a special rx and converted to DHT |
| Role of DHT on sperm development. | DHT diffuses into Sertoli nucleus and instructs DNA to make RNA -->RNA affect spermatogenic cells |
| Which male cx does LH bind to and what does it do? | Leydig cell - increases cholesterol --> T |
| What male cx does FSH bind to and what does it do? | sertoli cx - increases T --> DHT --> also synthesizes rx for T |
| What is the main androgen that affects sperm development? | DHT |
| Testosterone has negative feedback on? | hypothalamus and a. pituitary -LH |
| What happens when DHT is too high? | increase in inhibin which results in neg. feedback on a. pituitary -FSH |
| All the oogonia a female will ever produce is made during the first___? | 3 months |
| Atresia | process of oocyte degeneration |
| When does the secondary oocyte underogo second meiotic division? | after fertilization has taken place |
| When does primary oocyte undergo first meiotic division? | LH surge during puberty |
| What is a primary follicle? | primary oocyte surrounded by follicle cells |
| How long does follicular phase last? | 14 days |
| Layers of a primary follicle from outside to inside. | theca cx - granulosa cx - zona pellucida |
| Male: female :: leydig: ____ :: sertoli: ______ | theca / granulosa |
| When does ovulation occur? | once secondary oocyte is released |
| When does ovulation occur? | 14th day |
| ANtrum | primary follicle fluid that primes for ovulation |
| What does the burst follicle become? | corpus luteum |
| What is main fxn of c.l.? | secrete progesterone (and estrogen) to maintain endometrium lining |
| What do theca cx do? Where does it go after? | convert cholesterol --> T -diffuses into follicle cx to become Estrogen |
| In the female, LH affects the ____ cx while FSH affects the ______ cx. | theca / follicle |
| Low conc. of estrogen, there is _____ feedback on hypo and a.pit. HIgh conc. of estrogen, there is _______feedback on hypo and a.pit | -negative -positive |
| From ovulation to beginning of menstrual phase, what is that phase called? | luteal phase |
| Estrogen alone has _____ feedback. E and P in combo have ______. | positive /negative |
| What is importance of E and P produced from c.l.? | negative feedback and prevents another follicle from developing |
| What is the only thing that enters the secondary oocyte from the sperm? | nucleus |
| What mem. does the sperm contact during fertilization? | zona pellucida |
| When is HCG made? | ONLY during the first three months of pregnancy to maintain c.l. |
| What takes over the role of the c.l. once it degrades? | placenta --> makes more E and P |
| Cells of similar type form____? | tissues |
| What is the structure called that is opposite to where sperm penetrates the egg? | gray crescent |
| What is notochord derived from? | mesoderm |
| What gives rise to nervous ssytem? | neural plate |
| Where is neural plate derived from? | ectoderm |
| What is formed from neural plate? | neural groove --> spinal cord and brain |
| Intracellular interactions usually result in a _____. Intercellular interactions usually create ______. | -prepattern -developmental induction |
| Animal pole vs. vegetal pole | -animal pole = cytoplasm -vegetal pole = yolk |
| What sets up the initial prepattern? | grey crescent |
| Dorsal lip | area where cells from animal pole invaginate into blastula |
| What is main role of dorsal lip? | organizer of gastrulation and neuralation |
| In order for the uterus to be receptive, it MUST be? | quiescent |
| When is the uterus no longer quiescent? | At a certain ratio of P:E --> E increases faster than P |
| When are the 2 main estrogen surges? | -LH surge for ovulation -surge to induce contractions |
| 2 main fxns of oxytocin. | induce contractions and milk ejection |
| What does the formation of a primitive streak mark in mammals? | beginning of gastrulation followed by neuralation |
| When will the embryo reach the uterus? | by the 5th or 6th day --> blastocyst |
| What is the trophoblast? | surrounding ectodermal cx that cover inner cx mass |
| Chorion vs. allantois | chorion = gas exchange and transfer of nutrients allantois = gas exchange and get rid of wastes |
| What preserves teh barrier between the mother's and fetus' blood? | chorion - placenta |
| monozygotic twins | genetically identical offspring when single zygote splits in 2 |
| dizygotic twin (fraternal twins) | not genetically identical - 2 eggs are released and fertilized |
| What are 3 main shunts for fetal circulation? | -foramen ovale -ductus venosus -ductus arteriosus |
| Where is fetal respiration carried out in? | placenta |
| HOw is placenta formed? | from chorion |
| Does maternal and fetal blood mix together? | NO --> diffusion of everything |
| What forms peripheral nervous system? | ectoderm |
| adrenal cortex vs. adrenal medulla layers | -adrenal cortex = mesoderm -adrenal medulla = ectoderm |
| archenteron | -cavity created by deep invagination -later becomes gut |
| blastopore | -opening of archenteron -deuterosomes (humans), becomes anus -protosomes, becomes mouth |
| What in the urine is the first sign of pregnancy? | HcG |
| indeterminate cleavage vs. determinate cleavage | -cx that develop into complete organisms -cx that are determined to differentiate into a certain type of cx |
| totipotent cx | any cx could produce complete individual |
| morula | solid mass of embryotic stem cells |
| blastula vs. blastocyst | blastula - non mammals blastocyst - mammals |
| What doe s blastocyst consist of? | trophoblast and inner cell mass |
| trophoblast vs. inner cx mass | -trophoblast makes chorion and placenta -inner cx mass makes actual organism |
| Why is it so important during pregnancy to have neg. feedback on GnRH, LH, and FSH? | make sure development of another follicle |
| What does c.l. degrade into? | corpus albicans |
| What are 4 phases of menstrual cycle? | -follicular phase -ovulation -luteal phase -menstruation |
| What are all of the developmental stages? | -fertilization -cleavage -gastrulation -neuralation -neural crest formation -organogenesis |
| organogenesis | process by which layers of ectoderm, mesoderm, endoderm become internal organs |
| parthenogenesis | ovum develops into a new individual without fertilization |
| Are all nucleic acids circular / linear? | linear |
| Division of oocyte during meiosis creates uneven ____ but even ______. | cytoplasm / nuclear material |
| What does coelom form from? | mesoderm |
| How do contraceptives work? | inhibit LH surge by altering E/P levels --> suppress ovulation |
| SEVEP UP | seminiferous tubules, epididymus, vas deferens, ejaculatory duct, prostate, urethra, penis |
| What is a major sign for ovulation? | sudden rise in LH |
| Why are synthetic hx better? | last longer and less degraded |
| How long is each phase of the menstrual cycle? | -Menstruation (0-5) -Follicular (5-15) -Ovulation (24 hours) -Luteal (secretory) phase - 14 daysalways |
| What does LH release in males? | testosteroen |
| What are the 3 type of cell population? | -rapidly dividing - skin cx, tympanic mem, GI tract -stable cx - pancreatic and liver that are normally arrested in Go but can divide if necessary -permanent cx - nerve and cardiac - no mitotic activity |
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