More than one may be true

1. More than one may be true • 1. A cell contains two homologous sets of chromosomes. • a. The cell that contains these homologous sets of chromosomes must be diploid. • b. Each homologous pair of chromosomes was formed by DNA replication of a single chromosome. • c. Barring mutation, the two chromosomes in a homologous pair must be identical. • d. One member of each homologous pair is from the maternal family line; the other member is from the paternal family line.

2. Again, each letter is a question

3. Chapter 46. Animal Reproduction

4. Sexual & asexual reproduction • Asexual • offspring all have same genes (clones) • no variation unless there is mutation • Sexual • gametes (sperm & egg)  fertilization • mixing of genes  variation

5. Parthenogenesis • Development of an unfertilized egg • honey bees • drones = males produced through parthenogenesis  haploid • workers & queens = females produced from fertilized eggs  diploid queen worker drone

6. Hermaphrodites • Having functional reproductive system of both sexes earthworms mating flat worm

7. Fertilization • Joining of egg & sperm • external • usually aquatic animals • internal • usually land animals

8. Development • External • development in eggs • fish & amphibians in water • soft eggs= exchange across membrane • birds & reptiles on land • hard-shell amniotic eggs • structures for exchange of food, O2 & waste • sharks & some snakes • live births from eggs • Internal • placenta • exchange food & waste • live birth

9. Adaptive advantages? • What is the adaptive value of each type of sexual reproduction • number of eggs? • level of parental of care • habitat?

10. Reproductive hormones LH &FSH • Testosterone • from testes • functions • sperm production • 2° sexual characteristics • Estrogen • from ovaries • functions • egg production • prepare uterus for fertilized egg • 2° sexual characteristics testesorovaries

11. Sex hormone control in males Hypothalamus GnRH Pituitary FSH & LH Testes testosterone Body cells

12. Male reproductive system • Testicles • produces sperm & hormones • Scrotum • sac that holds testicles outside of body • Epididymis • where sperm mature • Vas deferens • tubes for sperm to travel from testes to penis • Prostate, seminal vesicles, Cowper’s (bulbourethal) glands • nutrient rich fluid to feed & protect sperm • buffer to counteract acids in vagina

13. seminiferous tubule Male reproductive system • Testes & epididymis • sperm production & maturation • Glands • seminal vesicles, prostate, bulbourethal • produce seminal fluid = nutrient-rich sperm spermatocytes

14. Spermatogenesis Testis Epididymis Germ cell (diploid) Coiled seminiferous tubules 1° spermatocyte (diploid) MEIOSIS I 2° spermatocytes (haploid) MEIOSIS II Vas deferens Spermatids (haploid) Spermatozoa Cross-section of seminiferous tubule

15. Female reproductive system • Ovaries • produces eggs & hormones • Uterus • nurtures fetus; lining builds up each month • Fallopian tubes • tubes for eggs to travel from ovaries to uterus • Cervix • opening to uterus, dilates 10cm (4 inches) for birthing baby • Vagina • birth canal for birthing baby

16. LH Menstrual cycle FSH Hypothalamus egg development ovulation = egg release GnRH corpus luteum Pituitary FSH & LH estrogen progesterone Ovaries lining of uterus estrogen Body cells days 0 7 14 21 28

17. Egg maturation in ovary • Corpus luteum • produces progesterone to maintain uterine lining

18. Female hormones • FSH & LH • release from pituitary • stimulates egg development & hormone release • peak release = release of egg (ovulation) • Estrogen • released from ovary cells around developing egg • stimulates growth of lining of uterus • lowered levels = menstruation • Progesterone • released from “corpus luteum” in ovaries • cells that used to take care of developing egg • stimulates blood supply to lining of uterus • lowered levels = menstruation

19. Oogenesis • What is the advantage of this development system? Meiosis 1 completed during egg maturation ovulation Meiosis 2 completed triggered by fertilization

20. Fertilization

21. Fertilization • Joining of sperm & egg • sperm head enters egg

22. Cleavage • Repeated mitotic divisions of zygote • 1st step to becoming multicellular • unequal divisions establishes body plan • different cells receive different portions of egg cytoplasm & therefore different regulatory signals

23. Cleavage • zygote  morula  blastula • establishes future development

24. Gastrulation • Establish 3 cell layers • ectoderm • outer layers • skin, nails, teeth, nerves • mesoderm • blood, bone & muscle • endoderm • inner lining • digestive system ectoderm mesoderm endoderm

25. Neural groove Notochord Neurulation • 1st organ to form is notochord & nerve chord • develop into nervous system Neural tube

26. Placenta • Materials exchange across membranes

27. Getting crowded in there!! • 32 weeks (8 months) The fetus sleeps 90-95% of the day & sometimes experiences REM sleep, an indication of dreaming

28. Hormone induction Birth positive feedback

29. Birth (36 weeks) Intestine Placenta Umbilical cord Wall of uterus Bladder Cervix Vagina

30. The end of the journey!

31. Contraception and Abortion • Contraception, the deliberate prevention of pregnancy, can be achieved in a number of ways • Contraceptive methods fall into three categories: • Preventing release of eggs and sperm • Keeping sperm and egg apart • Preventing implantation of an embryo

32. You should now be able to: • Distinguish between asexual and sexual reproduction • Explain how hermaphroditism may be advantageous to animals that have difficulty encountering a member of the opposite sex • Describe various ways in which animals may protect developing embryos • Using diagrams, identify and state the function of each component of the male and female reproductive systems

33. Describe oogenesis and spermatogenesis; describe three major differences between them • Explain how the uterine and ovarian cycles are synchronized and describe the functions of the hormones involved • List the various methods of contraception, how each works, and how effective each is • Describe techniques that allow us to learn about the health and genetics of a fetus