1 / 30

Animal Reproduction

Animal Reproduction. Differentiate mitosis and meiosis. List major differences between the two processes. Life on earth is transient. Only things that can reproduce have made it this far 2 major types of reproduction: Asexual Reproduction Sexual reproduction.

harmon
Download Presentation

Animal Reproduction

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Animal Reproduction

  2. Differentiate mitosis and meiosis. • List major differences between the two processes.

  3. Life on earth is transient • Only things that can reproduce have made it this far • 2 major types of reproduction: • Asexual Reproduction • Sexual reproduction

  4. In asexual reproduction, offspring are genetically identical to the parent • Binary fission, budding and fragmentation are examples of kinds of asexual reproduction

  5. Variety in offspring improves chances of adaptation to changing environments Sexual reproduction Generates diversity

  6. Artificial selection shows the variety available to a single species

  7. Despite an inherent twofold cost, higher species reproduce sexually • Sexually reproducing species must have 2 offspring to “break even” • 2 offspring from an asexually reproducing species doubles the population

  8. Sexual reproduction requires meiosis • Meiosis is the formation of haploid gametes (eggs and sperm) from diploid germ cells • Allows variation from reshuffling of genes

  9. Some species are hermaphroditic • C. elegans, a roundworm, is a model organism used in research • 1/1000 is a male (caused by a nondisjunction)

  10. Only sexual reproduction recombines genomes • 4 haploid sperm are produced from a diploid primary spermatocyte • Develped in the seminiferous tubules of testes

  11. Human spermatozoon

  12. Testes • Produce, nurture and store ~200-300m spermatozoa/day • <20m/day  sterility • Produced in seminiferous tubules • Stored in epididymis • Optimal temperature 1.5oC cooler than body temp. • Also important producer of testosterone

  13. Seminal Vesicles • First of 3 major accessory glands which add various fluids to semen • Provide ~70% of seminal fluid qty. • Includes nutrients (fructose), antibiotics to help sperm on their way • Sperm- 1% of semen volume

  14. Prostate gland • Accounts for 20-30% of seminal fluid by volume • Slightly basic in pH • Neutralizes

  15. Bulbourethral (Cowper’s) gland • Release clear mucosal fluid called pre-ejaculate • Flushes and lines the urethra for ejaculation

  16. Male Reproductive System

  17. Pharmacodynamics of Viagra • Parasympathetic nervous system increases concentration of NO in corpus cavernosum (erectile tissue) • NO binds to guanylatecyclase, which makes cGMP • cGMP relaxes smooth muscle, increasing bloodflow • Viagra is an inhibitor of PDE5, which degrades cGMP • More cGMP more bloodflow

  18. Cyclic GMP (cGMP) • Signaling molecule • Similar to ATP • ATP ADP  AMP  cAMP  signal = hungry! • In higher animals, signal can mean other things • ATP based on Adenine, GTP based on Guanine

  19. Female Reproductive system

  20. Oogenesis results in unequal division of cell cytoplasm • Ultimately, 3 polar bodies will be formed, and 1 ovum • FSH from pituitary gland stimulates a single 1o oocyte to complete meiosis I

  21. In oogenesis, Meiosis II is not completed until after fertilization

  22. Ovaries produce oocytes • Alternate with monthly release of 2o oocytes • Oocytes develop in follicles • Ruptured follicle becomes hormone source before degradation

  23. Female reproductive system • Oviduct- aka uterine tube, fallopian tube is site of fertilization • Uterus- womb for pregnancy • Endometrium- lining of uterus • Myometrium- muscular wall of uterus

  24. Female Reproductive system • Vagina- acid environment to fight infection • Bartholin’s gland- analogous to Cowper’s • Clitoris- nervous + erectile tissues

  25. The reproductive/ menstrual cycle is finely controlled by several hormones • GnRH from the hypothalamus stimulate the pituitary • FSH and LH from the pituitary stimulate follicular development • Estrogen and progesterone from the follicle and corpus luteum regulate hypothalamus

  26. Human sexual response is usually described in four phases • Excitement- penile/clitoral erection • Plateau- breathing/heart rate increase • Orgasm- ejaculation in males, contraction of uterus and vagina in females • Resolution- return to normalcy

  27. Pregnancy and disease transmission can be prevented • Diaphragm- covers cervical opening to uterus • Pill- simulates pregancy, thereby inhibiting ovulation • Condom- captures sperm, prevents disease transmissiom

  28. Fertilization forms a diploid zygote Usually occurs in fallopian tubes Implantation into uterine wall several days later

  29. Zygote Morula Blastula  Implantation

More Related