Explanation of Synapsis, Crossover, and Spermatogenesis in Chapter 43
CHAPTER 43
1) 1. C 7. B 2. B 8. A 3. A 9. B 4. B 10. C 5. C 11. B 6. A 12. B
2) Describe the process of synapsis The pairing of homologous chromosomes (23 tetrads become attached to spindle fibers & begin to align on the equator.
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3) How does crossover introduce variability in the daughter cells? The homologues separate from one another, breaking & exchanging parts- where crossovers occur
4) Define homologous chromosomes Egg & sperm chromosomes that carry genes for the same traits (1 paternal, 1 maternal)
5) 1. Primitive stemspermatogonium 2.Haploidsecondary spermatocyte, spermatid, sperm 3. Provides nutrients to developing spermsustentacular cells 4. Products of meiosis IIspermatid 5. Product of spermiogenesissperm 6. Product of meiosis Ispermatocyte
6) Why are spermatids not considered functional gametes? They are non-motile and have too much excess baggage to function well in a reproductive capacity.
7) Differentiate between spermatogenesis and spermiogenesis Spermiogenesis is the final stage of spermatogenesis, which sees the maturation of spermatids into mature, mobile spermatozoa. Formation of haploid gametes by male sloughing off excess spermatid cytoplasm to form a functioning sperm
8) Draw a sperm, label: acrosome, head, mid piece and tail. Beside each label, note the composition, and function of each sperm structures. Acrosome ( composition & function) penetrating device containing digestive enzymes Head ( composition & function) genetic region, nucleus Mid piece ( composition & function) contains mitochondria which provide ATP Tail ( composition & function) contractile filaments (loco motor region)
9) The lifep of a sperm is very short?
What anatomical characteristics might lead you to suspect this even if you don't know its life p? No cytoplasm in which to store nutrients
10) The sequence of events leading to germ cell formation in the female begins during fetal development, by the time the child is born; all viable oogonia have been converted to Primary oocytes How does the total germ cell potential of the female compare to that of the male? Much smaller, and the total number is predetermined
11) Female gametes develop n structures called follicles. What is a follicle?
A saclike structure containing follicle cells in one or more layers that enclose a developing gamete. How are primary and vesicular follicles anatomically different? Primary follicle=primary oocyte; a single layer of cuboidal/columnar follicle cells Secondary follicle=several layers of cuboidal/columnar cells collectively called the membranous granulose which secrete follicular fluid What is a corpus luteum? It is what's left of the follicle after a woman ovulates, glandular ovarian structure that produces progesterone.
The ruptured vesicular follicle is converted to corpus leuteum.
12) What is the major hormone produced by the vesicular follicle? Estrogen What is the major hormone produced by the corpus luteum? Progesterone (and some estrogen)
13) 1. B 2. C 3. C 4. D
14) The cellular product of spermatogenesis is four _____________; the final product of oogenesis is one ________ and three ____________ Spermatids, ovum, polar bodies. What is the function of the unequal result of oogenesis in the female?
To provide the ovum or functional gamete w/adequate nutritional reserves so that it can survive its journey to the uterus. What is the fate of the 3 tiny cells produced during oogenesis? Why? They will deteriorate; they lack sustaining cytoplasm w/nutrient reserves.
15) 1. FSH 2. LH 3. Estrogen and Progesterone 4. Estrogen 5. LH 6. LH
16) Why does the corpus luteum deteriorate toward the end of the ovarian cycle? Because blood levels of the anterior pituitary hormone LH are very low
17) 1. B 2. A 3. B 4. B 5. A
18) What uterine tissue undergoes dramatic changes during the menstrual cycle? Endometrium
19) When during the female menstrual cycle would fertilization be unlikely? Explain why? Anytime but the three-day interval (days 14-16) around ovulation (28 day cycle assumed)
20) Assume that a woman could be an "on demand" ovulator like the rabbit, in which copulation stimulates the hypothalamic-anterior pituitary axis and causes LH release, and an oocyte was ovulated and fertilized on day 26 of her 28-day cycle.
Why would a successful pregnancy be unlikely at this time? The uterine lining goes through a cycle of building up every cycle to accept an embryo. By the time day 26 comes along, the lining is getting ready to slough off during the next period. Most likely the lining of the uterus would not be able to support the implantation and development of the embryo at this time.
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