CWRU Bio 216 Exam 1 Kuemerle Questions With Correct Solutions!!

primordial germ cells (PGCs) - specific precursor cells that eventually undergo gametogenesis to become sperm or egg "P granules" - RNA and protein complexes that move to the posterior end of the zygote before the first cleavage and are found in adult germ cells (C. elegans) SOX9 and FGF9 - tfs activated by SRY in males RSPO9 and WNT4 - tfs activated in females Aneuploidy - Abnormal number of chromosomes Mitosis during Gametogenesis - purpose: expand PGC population interphase includes G1 (normal growth), S (DNA rep), G2 (increased growth) this is a CYCLE Meiosis during Gametogenesis - develops egg or sperm for reproduction independent assortment and crossing over cause genetic variation cells are n (haploid) after meiosis I this is a ONE WAY process Oogenesis - PGCs become oogonium, then the primary oocyte begins meiosis and is arrested at PROPHASE I This 2n cell splits into a polar body and a secondary oocyte (both n) secondary oocyte begins meiosis II and is arrested at METAPHASE II ovulation releases secondary oocyte and it matures when combined with sperm and meiosis II resumescorpus luteum - forms from ruptured follicle and produces progesterone to thicken uterine lining Spermatogenesis - PGCs become spermagonial stem cell (2n) then divide into spermatogonium and primary spermatocyte (can produce sperm) 2 secondary spermatocytes form (n) then divide into 4 spermatids that mature into 4 sperm cells (n) inhibin - prevents sperm formation through negative feedback by inhibiting FSH secretion male hormone secretion - LH: simulates testosterone production from Leydig Leydig: promotes spermatogenesis Testosterone: inhibits LH and GnRH production FSH: stimulates Sertoli cells to secrete inhibin menstrual cycle - Days 1-7: primary oocyte releases estrogen to inhibit LH and FSH Days 8-13: LH and FSH cause ovum release; estrogen peaks Day 14: follicle ruptures and ovulation begins; LH and FSH peak Days 15-28: progesterone peaks and follicle degenerates if not fertilized acrosome reaction - 1) sperm head fuses with egg and releases digestive enzymes 2) acrosomal process is extended by polymerized actin monomers sea urchin fertilization - EXTERNAL fertilization 1 sec: sperm contacts jelly egg coat 2 sec: acrosome breaks down jelly coat and bindin binds to the vitelline layer of the egg 20 sec: FAST block where Na+ enters egg; CORTICAL/SLOW block where Ca+ is released and vitelline layer hardens 5-40 min: egg is activated and increases metabolism to prep for first division at 90 min mammalian fertization - INTERNAL fertilization1) capacitation removes proteins from acrosome so sperm can be more motile and bind; triggered by basic HCO3- in vagina (5-6 hrs) 2) acrosomal enzymes dissolve zona pellucida (ECM of egg) and Ca+ flows in 3) sperm bind to zp3; zp2 and zp3 are cleaved and causes BLOCK 4) oocyte has 2nd meiotic division forming n ovum and polar body (12-36 hrs) 5) sperm and egg fuse DNA sea urchin cleavage - cell divisions with no significant growth - very rapid with no interphase it partitions embryo into blastomeres blastula created after 5-7 cleavage divisions and its a hollow cell ball with a fluid-filled cavity yolk distribution - influences cleavage pattern vegetal: most concentrated yolk amount animal: opposite of vegetal pole furrow: indentation on embryo surface