Download Cell Division: Mitosis and Meiosis

Cell Division:
Mitosis and Meiosis
Mitosis
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Cell division that results in two exact daughter
cells
There is an exact replication of the nucleus
Cell Cycle:
G1 Phase: Cell growth
S Phase: DNA Replication
G2 Phase: Growth and prep. for mitosis
Mitosis: nucleus is divided into two cells
Cytokinesis: Cytoplasm divides
G1 S
G2
Prophase Metaphase
Anaphase
Telophase Cytokinesis
Interphase
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G1, S and G2 phases
Period between cell divisions
DNA is replicated
Time for growth and normal cell activities
Centriole divides and starts to move
Prophase
Metaphase
Anaphase
Telophase
Prophase
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Centrioles move to opposite sides of cell
Chromosomes become thicker and coil
Spindles form
Nuclear membrane and nucleolus disappear
Metaphase
• The two centrioles are at opposite poles
• The paired chromosomes line up in the
MIDDLE
• Centromere attaches to spindles
Anaphase
• Chromatids separate
• Chromosomes move to opposite poles
Telophase
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Chromosomes un-coil
Spindles disappear
Nuclear membrane and nucleolus re-appear
Cytokinesis begins
– Cytoplasm divides
Meiosis
• Occurs in sex cells (gametes-sperm and egg cells)
• Only occurs in organisms that reproduce sexually
• Same steps as mitosis, except process is
completed twice
• Divides chromosome number in half
– 2n (diploid) to n (haploid)
• Results in 4 gametes
• Spermatozoa: Sperm
• Ova: Egg
Sexual vs. Asexual Reproduction
• Sexual Reproduction: Need a sperm and egg cell
– Genetic diversity
– Species can adapt (change) for environment quickly
– Slow population growth
• Asexual Reproduction: Can reproduce without a partner
– No genetic diversity
– Quick reproduction, may be good for survival rates
but organism will run out of resources quickly
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