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Meiosis Gamete Production

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Meiosis Gamete Production

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  1. MeiosisGamete Production

  2. MEIOSIS • Meiosis is specialized cell division resulting in sex cells with half the genetic material of the parents • Sex cells called GAMETES have exactly oneset of chromosomes, this state is called haploid(1n) • Regular body (somatic) cells have 2sets of chromosomes, this state is called diploid (2n) and divide through mitosis

  3. Humans have a TOTAL of 46 chromosomes (DNA) in each body cells. For a human baby, you need to pair up the chromosomes. Mom gives haploid cell (N=23) egg, Dad gives haploid cell (N=23) sperm (not in notes- write!) *If a cat’s egg has 10 chromosomes, how many would be found in the diploid cell? *If a dog has 38 chromosomes in the heart cell, how many will be found in the sperm cell?

  4. Produce 4 daughter cellswith different amount and differenttype ofDNA These cells are Haploid (1n) gamete: sex cells Ex. of gametes are sperm,egg, and pollen Meiosis is for sexualreproduction Sexual reproduction is 2 parents give DNA Meiosis

  5. Gametes Are Haploid • Gametes must have half the genetic material of a normal cell • If the genetic material in the gametes was not halved, when they combined the zygote would have more genetic material than the parents. THAT WOULD BE A MUTATION!

  6. Stages Of Meiosis • Meiosis resembles mitosis except that it is actuallytwodivisions not one • These divisions are called Meiosis I and Meiosis II

  7. Mother cell Interphase Prophase I: Condensing Chromosomes Prophase I: Tetrad formation/ crossing over Metaphase I Meiosis II Anaphase I Telophase I Stages Of Meiosis: Meiosis I

  8. Metaphase II Anaphase II Telophase II Telophase I Stages Of Meiosis: Meiosis II Prophase II The products of meiosis are 4 haploid cells each with a unique set of chromosomes. *The products of mitosis are 2 diploid cells with identical chromosomes.

  9. Crossing Over • Crossing over- A process occurring during meiosis(Prophase I) where twochromosomes pair up and exchange segments of their genetic material. • This is how we get genetic variationwhich means that even though you and siblings have the same parents- you all look different! (except for identical twins)

  10. Prophase I: Tetrad formation/ crossing over Metaphase I Telophase I Telophase II Anaphase I Crossing Over Because of crossing over, every gamete receives a unique set of genetic information.

  11. In The Beginning… • Two sex cells, a sperm and an egg, unite through the process of FERTILIZATION to form a zygote, the single cell from which the organism develops • Meiosis is the process of producing sperm and eggs (gametes) *remember mitosis is to produce body (diploid) cells

  12. Egg 1n Haploid nucleus Sperm 1n Haploid nucleus Fertilization Results In A Diploid Zygote

  13. Fertilization Results In A Diploid Zygote Egg 1n Haploid nucleus Sperm 1n Haploid nucleus

  14. Haploid nucleus Fertilization Results In A Diploid Zygote Egg 1n Haploid nucleus Sperm 1n

  15. Haploid nucleus Fertilization Results In A Diploid Zygote Egg 1n Haploid nucleus Sperm 1n

  16. Zygote 2n Zygote 2n From Zygote to Embryo

  17. From Zygote to Embryo MITOSIS now takes over to make a baby!

  18. From Zygote to Embryo Cleavage

  19. From Zygote to Embryo Cleavage

  20. From Zygote to Embryo Cleavage

  21. From Zygote to Embryo

  22. Mitosis Interphase (DNA replicates) Prophase Metaphase Anaphases Telophase (Cytokinesis) Final Product 2 identical cells Same DNA 2 sets of chromosomes Type of cell : Diploid (2N) Body cell Meiosis Interphase (DNA Replicates) Prophase Metaphase Anaphase Telophase Cytokinesis (2 daughter cells) Prophase II Metaphase II Anaphase II Telophase II Cytokinesis II Final Product 4 gamete different cells Mixed DNA 1 set of Chromosomes Type of cell: Haploid (N) gamete/sex cell Compare Mitosis vs. Meiosis

  23. When does mitosis occur? What kinds of cells are produced? When does meiosis occur? What kinds of cells are produced?

  24. Video • Amoeba sisters: Meiosis

  25. The End