Mitosis Division of somatic (body) cells Interphase Prophase Metaphase Anaphase Telophase Cytokinesis

Interphase Cell spend most time in this phase G1 – growth S – DNA is replicated G2 – preparation for mitosis .                                                     .                                                     .                                                    

Interphase This cell is called the parent cell The cell is diploid (2n) meaning it has two sets of chromosomes

Prophase Longest phase Nuclear membrane breaks down Sister chromatids pair up Chromatin thickens- can now see individual chromosomes Cenrioles take position Spindle fibers form

Metaphase Sister chromatids line up in center of spindle fibers Meta = middle

Anaphase Centromeres are split The sister chromatids are pulled apart Each half of the sister chromatid move to opposite centrioles

Telophase A new cell membrane starts to form down the middle of the cell - forming two new cells Chromatin thins out New nuclear membrane forms around each set of DNA

Cytokinesis Cytoplasm splits Two new cells are produced Called daughter cells IDENTICAL to parent cell In plant cells a cell plate forms, which is later replaced by the cell wall

???Questions??? If a parent cell has 8 chromosomes, how many chromosomes does each of the daughter cells have? 8 because the daughter cells are identical to parent cells If a body cell has 10 chromosomes, how many chromosomes does each somatic cell have? 10 because a body cell is a somatic cell If a sperm cell (sex cell) has 5 chromosomes, how many chromosomes does a skin cell have? 10 because the body cells (skin, hair, etc, have twice as many chromosomes as a sex cell (sperm or egg)

Controls on Cell Division Cells consistently divide to produce new cells;the rate however varies When you are injured the cells divide rapidly to produce new cells until you are healed and then the division slows down Proteins called cyclins were produced to help some cells continue to divide There are also proteins that regulate the speed of division

Cancer cells Cancer cells are body cells that cannot control growth Cancer cells continually reproduce and never spend time in interphase – forming clumps of cells = tumors These cells lack the regulators (internal or external) or they reproduce so fast that not all the chromosomes form therefore, the internal regulators don’t have time to be produced