Mitotic Cell cycle

  • CHROMATIN AND CONDENSTED CHROMOSOME

    Chromatin⇒ histone + DNA

  • REPLICATION AND MITOTIC CELL CYCLE

    Importance of mitosis in the production of genetically identical daughter cells during: • growth of multicellular organisms • replacement of damaged or dead cells • repair of tissues by cell replacement • asexual reproduction

    MITOTIC CELL CYCLE

    Interphase

    • G1- Cell makes RNA, enzymes and other proteins for growth

    • S PHASE- DNA REPLICATION

    • G2- cell growth, DNA checked for errors and repaired, tubulin made for spindle fibers.

    Mitosis Prophase- Chromosomes are replicated consist of two sister chromatids. Chromosomes condense; nuclear envelope disappears. Centrosomes move to opposite poles of nucleus. Metaphase- Chromosomes line up at the equator of the cell. Attached to spindle fibers by their centromere. Anaphase- Chromosomes are split into two chromatids as motor proteins walk along the spindle fibers in opposite directions. The chromosomes are pulled to opposite poles of cell. Telophase- Once the chromosomes reach the poles nuclear envelopes form around them, creating two identical nuclei. Cytokinesis This is after mitosis occurs, the cytoplasm of the cell will begin to divide creating two identical daughter cells.

    Telomeres

    The role of telomeres in preventing the loss of genes from the ends of chromosomes during DNA replication.

    When the telomeres disappear, the cell will die and be replaced by other cells.

    Stem cells are cells that can divide an unlimited number of times they can stay stem cells or become specialized cells.

    Totipotent- cells that can produce any type of cell e.g. zygote.

    Pluripotent- Embryotic stem cells

    CANCER

    Uncontrolled cell division can cause a tumor.

    Malignant tumors are cancer causing

    Benign tumors- not cancer-causing e.g. warts

    Reasons for uncontrolled cell division.

    • Carcinogens- UV light and oncoviruses

    • Constant rebuilding of telomeres by their enzyme telomerase. (chemotherapy targets those enzymes)

    • Cell is not getting to signal from other cells