Cell Division

Cell Structure

Made by Gregory B

  • Created by: Gregory B
  • Created on: 05-06-18 14:44
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  • Cell Division
    • Mitosis
      • 23 Pairs of chromosomes in human cell.
      • Mitosis is a type of cell division in which one cell (the mother) divides to produce two new cells (the daughters) that are genetically identical to itself.
        • Before a cell divides, its chromosomes are copied exactly. The DNA molecule is made of two strands. As each of the two strands separate, new strands are made alongside each of them, thereby making two new copies.
      • 1. chromosomes line up in the centre of the cell and the cell fibres pull them apart.
        • 2.  Membranes form around each set of chromosomes and the cytoplasm divides. .
          • 3. Now there are two cells  containing exactly the same DNA.
      • Chromatids = each of the two thread-like strands into which a chromosome divides longitudinally during cell division. Each contains a double helix of DNA.
      • Used for growth, repair and asexual reproduction
    • Cell division is the process by which a parent cell divides into two or more daughter cells. Cell division usually occurs as part of a larger cell cycle.
    • Interphase During interphase, the cell is preparing itself for division. Cells contain many proteins and structures called organelles that it must replicate in preparation for doubling.
      • ProphaseIn the phase to follow, called prophase, the duplicated chromosomes from the previous phase condense, meaning they become compacted and more tightly wound.
        • Metaphase Preceding metaphase is a period called prometaphase, during which the membrane, or nuclear envelope, surrounding the chromosomes breaks down, allowing the condensed chromosomes to come into direct contact with the microtubules of the mitotic spindle.
          • Anaphase During anaphase, the pairs of chromosomes, also called sister chromatids, are drawn to opposite poles of the elongated cell.
            • TelophaseThe most important characteristic of telophase is that the nuclear envelope, which had previously broken down to allow the microtubules to access and recruit the chromosomes to the equator of the dividing cell, reforms as two new nuclear envelopes around the separated sister chromatids.
              • Cytokinesis Cytokinesis, or the separating of the two daughter cells, begins during or after the final phases of mitosis. It occurs in animal cells happens when a fibre ring containing a protein called actin, located in the cell’s center, contracts, pulling the cell membrane to it, and subsequently squeezing the two nuclei apart.

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