How do little elephants grow up to be BIG elephants?

MITOSIS The process in which the nucleus divides to form two identical nuclei All human body cells, except sex cells, divide through mitosis

Mitosis Cycle Interphase (before mitosis begins) Prophase Metaphase http://www.cellsalive.com/mitosis.htm Interphase (before mitosis begins) Prophase Metaphase Anaphase Telophase & Cytokinesis (after mitosis)

Interphase is a long period of growth and development Chromosomes are copied (# doubles) CELL MEMBRANE Nucleus Cytoplasm

Plant Cell Animal Cell

Mitosis begins (cell begins to divide) A duplicated chromosome has two identical tightly coiled DNA strands, called chromatids, that are held together at a region called the centromere. Centrioles (or poles) appear and begin to move to opposite end of the cell. Spindle fibers form between the poles Nuclear membrane disappears. . Centrioles Sister chromatids Spindle fibers

Plant Cell Animal Cell Spindle fibers Centrioles

Chromatids (or pairs of chromosomes) attach to the spindle fibers and line up in the middle of the cell. Centrioles Spindle fibers

Plant Cell Animal Cell

Spindle fibers shorten and Chromatids(or pairs of chromosomes) separate and begin to move to opposite ends of the cell. The chromatids are now separated and are called chromosomes. Centrioles Spindle fibers

Plant Cell Animal Cell

Spindle fibers disappear. Chromosomes uncoil. Mitosis ends. Two new nuclei form. Spindle fibers disappear. Chromosomes uncoil. Mitosis ends. Nuclei Nuclei Chromosome

Plant Cell Animal Cell

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                                                             

Cell Cycle

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

MEIOSIS Cell division for sex cells (sperm and egg) TWO divisions of the nucleus Meiosis I Two cells form Meiosis II Both of the cells from Meiosis I form two cells for a total of four sex cells. Each sex cell has one-half the number of chromosomes in its nucleus that was in the original nucleus. From a human cell with 46 paired chromosomes, meiosis produces four sex cells each with 23 unpaired chromosomes.

Meiosis I Meiosis II

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