Asexual Reproduction Mitosis The process in which the nucleus divides to form two new nuclei. 1

How do little elephants grow up to be BIG elephants?

Why do animals shed their skin?

Three reasons why cells reproduce by asexual reproduction: 1. Growth 2 Three reasons why cells reproduce by asexual reproduction: 1. Growth 2. Repair 3. Replacement Skin cancer - the abnormal growth of skin cells - most often develops on skin exposed to the sun. Cell that reproduce by asexual reproduction reproduce constantly.

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

Paper Plate #1-Interphase occurs before mitosis begins Gap 1 Phase – Cell grows to mature size – organelles are duplicated Synthesis (S) Phase – Chromosomes are copied Gap 2 (G2) Phase – Cell continues to grow and prepares to divide CELL MEMBRANE Nucleus Cytoplasm

7th Period Gifted Class Only G1 – checkpoint Is the Cell large enough? Are sufficient nutrients available? Are growth factors present? G2 checkpoint Was DNA replicated correctly? Is the cell large enough?

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

Paper Plate #2 Prophase -1st step in Mitosis Mitosis begins (cell begins to divide) Chromotin strands condense to form chromosomes Nuclear membrane breaks down Spindle fibers form a bridge between the two ends of the cell. Centrioles Sister chromatids Spindle fibers

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

Paper Plate #3 Metaphase - 2nd step in Mitosis Chromatids (or pairs of chromosomes) line up in the center of the cell and attach to the spindle fibers at the centromere. Centrioles Spindle fibers

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

Paper Plate #4 Anaphase - 3rd step in Mitosis Chromatids (or pairs of chromosomes) separate at the centromere Each chromatid moves to the opposite end of the cell along a spindle fiber Centrioles Spindle fibers

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

Paper Plate #5 Telophase - 4th step in Mitosis Two new nuclei form. Chromosomes appear as chromatin (threads rather than rods). Mitosis ends. Nuclei Nuclei Chromatin

It is only the final stage that differs in plant and animals In animal cells a ring of actin filaments forms round the equator of the cell and then tightens to form a cleavage furrow which splits the cell into two In plant cells vesicles move to the equator, line up and fuse to form two membranes called the cell plate. A new cell wall is laid down between the membranes, which fuse with the existing well wall.

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

Paper Plate #6 Cytokinesis occurs after mitosis Cell membrane moves inward to create two diploid daughter cells have formed– each with its own nucleus with identical chromosomes.

Mitosis produces identical offspring

Animal Mitosis -- Review Interphase                                                              Prophase                                                              Metaphase                                                              Anaphase                                                              Telophase                                                             

Plant Mitosis -- Review Interphase                                                              Prophase                                                              Metaphase                                                              Anaphase                                                              Telophase                                                             

Cell Cycle

- Cell Division The Cell Cycle 24

Cancer? Unregulated mitosis Benign Malignant/ metastasis

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