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Ch 32 Animal Reproduction

Ch 32 Animal Reproduction . AP Biology Lecture . Asexual Reproduction . Requires one organism Identical copy of parent Methods Budding New individual forms as an outgrowth Regeneration Complete individual formed from a piece of an organism Parthogenesis

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Ch 32 Animal Reproduction

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  1. Ch 32 Animal Reproduction AP Biology Lecture

  2. Asexual Reproduction • Requires one organism • Identical copy of parent • Methods • Budding • New individual forms as an outgrowth • Regeneration • Complete individual formed from a piece of an organism • Parthogenesis • Develop from unfertilized eggs

  3. Sexual Reproduction • Most animals • Requires two organisms • Genetic diversity • Three fundamental steps • Gametogenesis • Spawning or mating • Fertilization

  4. Gametogenesis • Production of haploid gametes • Gonads • Male; testes; produce sperm called spermatogenesis • Female; ovaries; produce ova called oogenesis Gametes are produced by germ cells that proliferate into spermatogonia and oogonia. These then multiple into primary spermatocytes and primary oocytes which make sperm and ova. Hermaphrodites*

  5. Fertilization • Fusion of gametes • Series of events • Sperm and ova bind by species specific molecules Mammal ovum is protected by thick gelatinous (cumulus) that surrounds an envelope (zonapellucida or zona) When sperm comes in contact with zona receptors signals release an enzyme that digests a pathway through the zona for the sperm. Ovum membrane proteins aid in the fusion of the sperm and ovum. • Sperm activated and allowed into the plasma of ovum

  6. 3. Plasma membranes fuse and ovum blocks additional sperm entry fast block – prevents fusion of any other sperm (not present in mammals) slow block – envelope turns into a physical barrier that sperm can not penetrate (mammals have something like this) 4. Ovum activated and stimulated to start development 5. Nuclei fuse

  7. External fertilization • Spawning, requires a large amount of gametes • Internal fertilization • Requires accessory sex organs to enable sperm transfer • Copulation requires mating behaviors and physical joining of male and female sex organs

  8. Male • Spermatogenesis begins at puberty and continues through out a male’s life • 4 sperm produced each time • Males produce 100 million sperm a day • Sperm produced in the testes • Testes located in the scrotum • Outside the body for optimal sperm temp to be lower than body temp • Scrotum can pull testes closer to the body to gain heat or relax away to release heat • Semen is a mixture of substances that support the sperm and the fertilization process

  9. Seminiferous tubules • In each testes, where sperm is made • Leydig cells • Also in testes, make testosterone Sperm mature in epididymis then move to vas deferens. Vas deferens joins the seminal vesicles where it gets seminal fluid made by seminal vesicles, prostate gland and bulbourethral gland. Semen moves into the ejaculatory duct then to the urethra.

  10. Female • Oogenesis • Primary oocyte enters prophase I then remains there until puberty or longer (menopause) • When first meiotic division is complete two daughter cells do not split the cytoplasm equally. • Daughter cell will most (almost all) of the cytoplasm becomes the secondary oocyte. The other one is called the first polar body. • Second phase of meiosis may never happen and may wait until fertilization by sperm • Secondary oocyte goes through meiosis to produce one large daughter cell, eventually matures into the ovum, and a second polar body.

  11. Roles • Produce ova • Ovum matures and releases from the ovary to the fallopian tube (oviducts). Fertilization takes place in the upper regions of the oviduct. Fertilization or not, ovum moves to the uterus. Uterus has a neck called the cervix and vagina is the opening to the outside of the body. Sperm has to move from vagina to the oviduct. • Accept sperm • Nurture embryo

  12. If the ova is fertilized it will implant into the uterine wall, endometrium • Oviparous – lay eggs. Embryo develop outside the mother’s body Insects, reptiles, birds • Viviparous- live birth, embryo develop inside the mother’s body Mammals

  13. http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter28/animation__spermatogenesis__quiz_1_.htmlhttp://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter28/animation__spermatogenesis__quiz_1_.html

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