Mitosis and the Cell Cycle Big Idea: Mitosis is the process in which the nucleus divides to form two new nuclei and two cells with identical DNA. Mrs. Camp 7th Grade Life Science 1

How do little elephants grow up to be BIG elephants?

Why do animals shed their skin?

Mitosis begins after fertilization 1 cell becomes 2 cells, becomes 4 cells…becomes TRILLIONS

Why do cells make more cells? Three reasons why cells reproduce by asexual reproduction: 1. Growth 2. Repair 3. Replacement

Important Terms Somatic Cells – body cells Produced through mitosis Has 46 chromosomes (23 pairs) Homolog – each member of a chromosome pair Diploid (2n) – total of 46 chromosomes in people – zygote & somatic cells Haploid (n) – total of 23 chromosomes in people, gametes (sperm & egg)

Animated Mitosis Cycle http://www.cellsalive.com/mitosis.htm Interphase Prophase Metaphase Anaphase Telophase & Cytokinesis

Interphase occurs before mitosis begins Chromosomes are copied (# doubles) Chromosomes appear as threadlike coils (chromatin) at the start, but each chromosome and its copy(sister chromosome) change to sister chromatids at end of this phase CELL MEMBRANE Nucleus Cytoplasm

Interphase Plant Cell Animal Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Stages of Interphase Growth Stage 1 (G1) – metabolic activity of the cell Synthesis Stage (S) – metabolic activity of the cell, replication of DNA Growth Stage 2 (G2) – metabolic activity of the cell, prepare for division

Prophase 1st step in Mitosis Mitosis begins (cell begins to divide). Centrioles (or poles) appear and begin to move to opposite ends of the cell. Nuclear Envelope disappears. Spindle fibers form between the poles. Centrioles Sister chromatids Spindle fibers

Prophase Plant Cell Animal Cell Spindle fibers Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Metaphase 2nd step in Mitosis Chromatids (or pairs of chromosomes) attach to the spindle fibers at the centromere. Chromosomes move to the equator of the cell. Centrioles Spindle fibers

Metaphase Plant Cell Animal Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Anaphase 3rd step in Mitosis Chromatids (or pairs of chromosomes) separate and begin to move to opposite ends of the cell. Centromere is broken in half. Centrioles Spindle fibers

Anaphase Plant Cell Animal Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Telophase 4th step in Mitosis Two new identical nuclei form (nuclear envelopes reform). Chromosomes uncoil and appear as chromatin (threads rather than rods). Mitosis ends. Nuclei Nuclei Chromatin

Telophase Plant Cell Animal Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Cytokinesis occurs after Mitosis Cell membrane moves inward to create two daughter cells – each with its own nucleus with identical chromosomes.

Animal Mitosis -- Review Interphase                                                              Prophase                                                              Metaphase                                                              Anaphase                                                              Telophase                                                             

Plant Mitosis -- Review Interphase                                                              Prophase                                                              Metaphase                                                              Anaphase                                                              Telophase                                                             

IPMATC REMEMBER! Interphase Prophase Metaphase Anaphase Telophase Cytokinesis IPMATC A mnemonic to help remember the stages of mitosis. I Prefer Meatloaf At Tennis Camp

Cell Cycle

- Cell Division The Cell Cycle 24

Mitosis Animation http://www.cellsalive.com/mitosis.htm