Ms. Shafner CP Bio Mitosis (Sections 10.1 – 10.3) and Meiosis (Sections 11.4) Cell Division

 Make a more efficient cell  Growth of an organism  Abnormal growth (cancer)  Repair errors/damaged cells  Reproduction  Sexual and Asexual Why do cells divide?

 Fusion of two separate reproductive cells (gametes)  Offspring inherits genetic information from each parent  Happens in most plants and animals  Survival Strategy: Genetic diversity allows for better adaptation, can get protection in return  Survival Issues: Mating takes time Sexual Reproduction  Cell simply divides  Offspring is identical to parent  Happens in bacteria, Hydra and some plants  Survival Strategy: fast reproduction, characteristics for each generation  Survival Issue: same characteristics in a changing environment Asexual Reproduction

 Eukaryotic – Multiple Chromosomes  Condense to allow for equal separation of DNA  Prokaryotic – Single Circular Chromosomes Preparing for Division

 DNA Duplicates in a circular pattern  DNA attaches to cell membranes and fibers that begin to pull cell apart  Membrane indents and begins binary fission  Results in two identical daughter cells Prokaryotic Cell Cycle

Eukaryotic Cell Cycle  Interphase  G1 or “gap 1” – Cell growth  S or “synthesis” – Chromosomes are replicated  G2 or “gap 2” - Organelles are produced  M – Production of two daughter cells  Mitosis - Separation of nucleus  Cytokinesis - Separation of cytoplasm

Mitosis – Jig Saw  Prophase  Metaphase  Anaphase  Telophase  Cytokinesis

 Cyclins are proteins that regulate the cell cycle  Internal Regulator proteins – tell the cell when to continue dividing once certain points are met in the cell  External Regulator proteins – tell cell to speed up or slow down  Growth Factors stimulate cell cycle – important with embryos and wounds  Apoptosis – “programed” cell death  Cell growth can be out of control… can you think of a situation? Control of the Cell Cycle