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Somatic Cell Division

Somatic Cell Division. Mitosis. Somatic Cells. All body cells except gametes (sex cells). Somatic Cell Division. A cell divides into two identical cells Replaces dead or injured cells Adds new cells for tissue growth. DNA Replication (Duplication).

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Somatic Cell Division

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  1. Somatic Cell Division Mitosis

  2. Somatic Cells • All body cells except gametes (sex cells)

  3. Somatic Cell Division • A cell divides into two identical cells • Replaces dead or injured cells • Adds new cells for tissue growth

  4. DNA Replication (Duplication) • The DNA sequences that make up the chromosomes have to be copied so the same genetic material can be passed on to the new cells

  5. Cell Cycle • The sequence of changes a cell undergoes from the time it forms until the time it duplicates its contents and divides into 2 cells • Two major time periods: • Interphase – not dividing • Mitotic Phase - dividing

  6. Interphase • The cell replicates DNA and manufactures additional cell organelles and cytosolic components • High metabolic activity • Most growth

  7. DNA Replication • DNA nucleotides are synthesized in the cytosol and imported to the nucleus • The helical DNA uncoils and the 2 strands separate between the base pairs • The exposed base pair on each strand pairs with a newly synthesized complementary nucleotide • The new DNA strands take shape as chemical bonds form

  8. DNA Replication - continued • The original DNA molecule has become 2 identical strands of DNA • Once a cell completes DNA replication, the mitotic phase can begin.

  9. Mitotic Phase • Mitosis – division of the nucleus • Cytokinesis – division of the cytoplasm

  10. Nuclear Division • The duplicated chromosomes become divided such that one set ends up in each nucleus • The process is divided into 4 stages: • Prophase, Metaphase, Anaphase and Telophase **Mitosis is a continuous process and one phase merges with the next**

  11. Prophase • Chromatin fibers condense and shorten into chromosomes • Each prophase chromosome consists of a pair of identical double stranded chromatids • Mitotic Spindle is formed by the pericentriolar material and centrioles are pushed to opposite sides of the cell • The nucleolus and nuclear envelope break down

  12. Metaphase • The centromeres of the chromatid pairs are aligned along the center of the mitotic spindle – this is called the metaphase plate

  13. Anaphase • The centromeres split, separating the chromatid pair, which move to opposite ends of the cell. • Once separated the chromatids are called chomosomes.

  14. Telophase • Final stage of mitosis • Begins when chromosome movement stops • The chromosomes start to uncoil, a new nuclear envelope forms, nucleoli appear and the mitotic spindle breaks up. • TWO nuclei are present and the cell starts to divide into 2

  15. Cytoplasmic Division - cytokinesis • Division of the cell’s cytosol and organelles • Begins in late anaphase/early telophase with the formation of a cleavage furrow • Cleavage Furrow – slight indentation of the plasma membrane

  16. Checkpoint • What is the difference between a chromatid and a chromosome? • In which stage of the cell cycle is the cell growing? • What are the mitotic phases in order? • What is a major event in each stage?

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