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LG: How Do We Produce Gametes? 3/31

LG: How Do We Produce Gametes? 3/31. DO NOW: JE . Check your answer. JE . Draw the steps in the proper order. Label each. The last step has been completed for you. Then, write a summary statement about this process.

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LG: How Do We Produce Gametes? 3/31

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  1. LG: How Do We Produce Gametes? 3/31 DO NOW: JE

  2. Check your answer

  3. JE • Draw the steps in the proper order. Label each. The last step has been completed for you. • Then, write a summary statement about this process. Summary: _______________________________________________________________________ _________________________________________________________________________________ _________________________________________________________________________________

  4. (my OH sis)

  5. What are sex cells? Sex cells in animals and plants are called gametes. In animals, the gametes are eggs (ova) and sperm. In mammals, egg cells are produced in the ovaries, and sperm cells are produced in the testes. How are these cells specialized for their roles in reproduction? flexible tail for swimming lots of mitochondria for providing energy food source in cytoplasm for embryo enzymes to digest egg cell membrane protective outer cell layers

  6. How Does Meiosis Make Gametes? Male: 4 functional Haploid sperms are produced. Female: 1 functional Haploid egg is produced; 3 are polar bodies (disintegrate)

  7. What is fertilization? Fertilization is the stage of sexual reproduction when gametes fuse. This zygote divides by mitosis many times and becomes an embryo. When an egg cell is fertilized, it becomes a zygote.

  8. How many chromosomes in gametes? Human gametes only have 23 chromosomes. Gametes are said to be monoploid or haploid cells (n) Human somatic cells have 46 chromosomes. Somatic cells are said to be diploid cells (2n)

  9. What is meiosis? Gametes are produced by a type of cell division called meiosis. The number of chromosomes is halved in meiosis so it is sometimes called reduction division. Unlike mitosis, meiosis produces four (4)unique daughter cells. Why is it important to produce genetically unique gametes? It ensures natural variation within a species.

  10. Increasing genetic variation Meiosis produces genetically-unique daughter cells, but how does this happen? In the early stages of meiosis, homologous chromosomes exchange DNA, which creates genetic variation and new combinations of characteristics. This is called crossing-over. homologous pair before crossing-over homologous pair after crossing-over

  11. Genetic Variations • Crossing Over or Synapsis creates genetic variations.

  12. Homologous Chromosomes • The two chromosomes from a particular pair, normally one inherited from the mother and one from the father, containing the same genetic loci in the same order

  13. What happens during meiosis?

  14. The stages of meiosis

  15. Chromosomes during meiosis

  16. Mitosis vs. Meiosis • http://www.pbs.org/wgbh/nova/miracle/divide.html

  17. Mitosis vs. Meiosishttp://www.bbc.co.uk/schools/gcsebitesize/science/add_edexcel/cells/mitosisact.shtml

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