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Mitosis and Meiosis Growth, Repair, and Reproduction.

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Presentation on theme: "Mitosis and Meiosis Growth, Repair, and Reproduction."— Presentation transcript:

1 Mitosis and Meiosis Growth, Repair, and Reproduction

2 Some vocabulary to know Somatic cell: a body cell having the full complement of Chromosomes (humans = 46) Diploid: having the full complement of chromosomes, both members of each pair (2N) Gamete: a sex cell, like egg, sperm, pollen, having only one of each of the paired chromosomes from an organism. (humans =23) Haploid: having half the complement of chromosomes, one of each pair (1N)

3 Mitosis Purpose: to produce new cells for growth or repair of body tisuse. Triggered when cell gets too large, or when cell senses a space nearby (like in a cut). Outcome: 2 daughter cells that are identical clones of original somatic cell. In humans: one cell with 46 chromosomes produced 2 daughter cells each having 46 chromosomes.

4 The Stages of Mitosis As interphase ends, cell is large and has duplicated its DNA. The DNA strands are holding onto their copies. PROPHASE: chromosomes holding onto their copies become visible, nuclear membrane dissolves METAPHASE: chromosomes line up at middle of the cell, spindle fibers connected to centromeres ANAPHASE: spindle fibers separate each chromosome form its copy, pulling the copies to opposite poles TELOPHASE: reverse of prophase: nuclear membrane reforms, chromosomes loosen and become less visible

5 Meanwhile back at the gonads…. Mitosis will occur, but certain cells will be triggered to continue into meiosis to form sex cells.

6 Crossing Over occurs in Meiosis Crossing Over increases diversity in species, it mixes up the genes that came from your parents so the same traits don’t always get inherited together.

7 The steps of Meiosis

8 The result: 4 haploid cells

9 Fertilization recombines the chromosomes 2N-a zygote!

10 A new life begins again with mitosis…

11 Ob-La-Di, Ob-La-Da…


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