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Sexual Reproduction

Sexual Reproduction. Living Environment. Involves 2 two sexes, Male and Female. Gametes = sex cells – produced in gonads. Female = ovaries (gonads) produce egg cells (gametes). Male = Testes (gonads) produce sperm cells (gametes).

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Sexual Reproduction

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  1. Sexual Reproduction Living Environment

  2. Involves 2 two sexes, Male and Female. Gametes = sex cells – produced in gonads. • Female = ovaries (gonads) produce egg cells (gametes). • Male = Testes (gonads) produce sperm cells (gametes)

  3. Gametes plus other organs necessary to carry out reproduction = reproductive system. • Examples: uterus, cervix, prostate gland…

  4. Meiosis

  5. Hermaphrodites – Usually slow moving organisms. Earthworm, snails, hydra… • Produce both Eggs an Sperm but can not self-fertilize. • Exchange sperm with another individual to fertilize both eggs.

  6. Process of Gametes forming in the Gonads • Two types: • Oogenesis = eggs • spermatogenesis = sperm. • Eggs are Round • non-motile, nucleus, contain yolk, much larger then sperm, In humans about 0.1mm in diameter.

  7. Sperm are Microscopic. • Made up of a tail, neck and head. • Head is the nucleus which contains chromosomes and an acrosome, which helps the sperm, penetrate the egg. • Neck contains mitochondria, which provide energy • Tail is long and whip like. • Allows sperm to move

  8. Spermatogenesis

  9. Oogenesis

  10. Fertilization Overview: Egg + Sperm = Fertilization (Monoploid) + (Monoploid) = Zygote(Diploid)

  11. Fertilization Step By Step: • Sperm is released by the male their flagella begin to beat rapidly pushing them in all directions. • Sperm comes in contact with Egg. • Acrosome releases enzymes that dissolve an opening through the egg. • Head enters the egg while tail remains outside. • Head moves towards nucleus of egg. • Chromosomes come together. • Once egg is fertilized a protective membrane surrounds the zygote, which does not allow any other sperm cells to enter the egg cell.

  12. Fertilization of a mammalian egg: • http://brodylab.eng.uci.edu/cgi-bin/jpbrody/animation/files/16-980581646.html

  13. 2 Types of Fertilization: • External Fertilization – eggs are fertilized in the environment outside the female body. • Can only occur in aquatic environments. Very hazardous. Increase chances of survival by hormones and quantity.

  14. Internal Fertilization – occurs inside the body of the female. Mostly mammals. • Require specialized sex organs to transfer the sperm from the body of the male to the body of the female. • Body of the female most be moist so sperm can swim. • After fertilization zygote forms a hard protective shell and develops outside the female body or remains inside the female body throughout development.

  15. Parthenogenesis • development of an unfertilized egg • Occurs in many insects including bees, wasps, and some ants.

  16. Websites • Mitosis Animation: • http://biology.about.com/library/blmitosisanim.htm • Meiosis Animation: • http://biology.about.com/library/blmeiosisanim.htm • Meiosis written explanation: • http://www.biology.arizona.edu/cell_bio/tutorials/meiosis/page3.html • Fertilization of a mammalian egg: • http://brodylab.eng.uci.edu/cgi-bin/jpbrody/animation/files/16-980581646.html

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