Cell Division

CELL CYCLE The cell cycle is divided into 3 main stages: Mitosis when the nuclear division occurs and the cell splits. Interphase, when the cell is carrying out its normal cellular functions and chromosomes are replicated, Cytokinesis- division of the cytoplasm

3 Stages of Interphase: Pull Protein Synthesis and other cell processes are occuring The cell is busy being a cell!! The cell grows and develops. G1 Phase: The beginning of interphase Pull DNA begins to shorten and coil (chromosomes are starting to form). The cell prepares for mitosis. Centrioles are replicated. G2 Phase: Pull S Phase: T he DNA is replicated forming two identical copies of each chromosome. Interphase- *A cell spends 90% of its life in interphase. *Chromosomes are replicated. * A cell grows to full size.

MITOSIS: Cell division Results: Mitosis results in 2 identical daughter cells that are diploid. Diploid: Cells that have 2 copies of each chromosome or a full set (2n) of genetic information (DNA). Somatic (body) cells are diploid.

P URPOSE OF MITOSIS: Growth: Mitosis is how your body makes new cells so you can grow.

Repair: Mitosis is how your body repairs itself. P URPOSE OF MITOSIS:

Maintenance: Replace cells that are replaced throughout life. P URPOSE OF MITOSIS: While you have been reading this sentence around 50,000 cells have died and been replaced. The average age of all the cells in an adults body may turn out to be as young as 7-10 years old. Your epidermis is constantly replacing new skin cells. The life span of skin cells in an adult is about 50 days. Intestinal cells are replaced about every 5 days. In 3-4 months your whole blood supply is completely replaced. A blood cell lasts days. Every day 1% of your blood cells are replaced. Other cells are never (or very slowly) replaced, like skeletal muscle cells or neurons. The roots of your hair are always growing.

WHAT DOES MITOSIS HAVE TO DO WITH ME? 1.Mitosis out of control = cancer 2.Mitosis that stops early =advanced aging or disease such as progeria

3.Many diseases are related to problems with cell division: *Cancer *Alzheimers *Parkinson's

STAGES OF MITOSIS

Spindle Fibers Spindle fibers start to form. Chromosome Chromatin winds up to form chromosomes. Centrioles Centrioles move the the sides (poles) of the cell. 1.Prophase: The nuclear membrane dissolves nuclear membrane Link to Chromosome Structure

Line Up A)Chromosomes line up in the center of the cell. Spindle Fibers B )Spindle fibers attach to the centromere. 2. Metaphase:

Chromosome Double stranded chromosomes separate. Spindle fibers anchored to centrioles pull the chromosomes towards the sides of the cell. 3. Anaphase:

Chromosome A)Chromosomes continue to moving to the sides of the cell. Spindle Fibers B )Spindle fibers dissolve 4. Telophase: C)Chromosomes unwind to reform chromatin. Chromatin E)The cell will reenter interphase. Interphase

Cytokinesis

Of those 24 hours, approximately 22 hours the cell is in interphase (G1, S, and G2 Phases). Duration of Cell Cycle Then it takes only 2 hours to complete mitosis (prophase - telophase). On average a cell takes 24 hours to complete the cell cycle.

Put the following stages of mitosis in order.