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biologyexam3review

Mitosis cell steps interphase g1 s g2 mitotic division

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Mitosis: cell division/reproduction, steps- interphase (G1, S, G2) & mitotic division Most multicellular, eukaryotic organisms have 3 categories of cells Stem cells : continue to divide & can eventually differentiate into a variety of cell types Other cells capable of dividing : e.g. dividing liver cells, which can only become more liver cells Permanently differentiated cells : e.g. most heart & brain cells cannot divide 3 mitotic checkpoints, apoptosis - 3 checkpoints to ensure that: o 1. The DNA is suitable for replication At the juncture of G 1 to S o 2. The cell successfully completes DNA synthesis during interphase At the juncture of G 2 to mitosis o 3. Proper chromosome movements occur during mitotic cell division Between metaphase and anaphase (mid-mitosis) - If any checkpoint is not passed the cell goes through apoptosis : programmed cell death - Apoptosis has 2 functions: - 1. Destroy cells that are not in good condition (old, infected with a virus, malfunctioning, etc.) - 2. Destroy un-needed cells, especially during embryonic development Meiosis: cell division to make gametes, steps- 2 divisions Should be able to tell mitosis from meiosis from examples - Meiosis = specialized cell division process that makes haploid gametes (sperm or eggs) o Also called “meiotic cell division” o Only occurs in animal ovaries & testes o For sexual reproduction o (fusion of gametes to produce offspring) - Meiotic cell division produces gametes with half the genetic information of their parent cells o NOT identical/clones of parent cell o Full genetic info (diploid) is restored upon fusion of a sperm & egg
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