5-MITOTIC CELL CYCLE

• Telomeres protect the DNA from being lost in DNA replication and prevent chromosomes from fusing with each other
• Where does the kinetochore form and the spindle microtubule detach?

  The centromere
• Histones pack DNA into chromatins
• Cell cycle

  Interphase

  • G1: First growth phase after cell division
  • S phase: The DNA replicates
  • G2: Second growth phase
  • M phase: When nuclear division takes place (followed by cell division)

  Mitosis (PMAT)

  Cytokinesis (cell splits into 2 daughter cells)

  Resting phase
• Importance of mitosis

  • The daughter cells produced are genetically identical with the same number of chromosomes and this enables unicellular zygotes to grow into multicellular organisms
  • Mitosis is the basis of asexual reproduction
  • Cells are constantly dying and being replaced by identical daughter cells using mitosis followed by cell division
• What is mitosis?

  Mitosis is the nuclear division that produces 2 genetically identical daughter nuclei, each containing the same number of chromosomes as the parent nucleus
• MITOSIS

  PMAT

  • (P)prophase: Chromatin condenses to form chromosomes, nuclear envelope disappears and the spindle apparatus forms
  • (M)Metaphase: The chromosomes get arranged at the equator and the centromere is attached by the spindle
  • (A)Anaphase: Chromatins move to opposite poles, centromeres first
  • (T)Telophase: Chromosomes decondenses to chromatids, nuclear envelope reappears and the spindle apparatus disappears
• Cytokinesis: Division of the cytoplasm and cell into 2 by constriction from the edges of the cell
• What is a stem cell?

  A cell that has the ability to continuously divide and differentiate and develop into various other kinds of cells and tissue
• 3 types of potency

  Totipotency: An isolated cell that is able to produce an entire organism

  Pluripotency: A particularly potent type of stem cell that normally only exists during early embryonic development

  Multipotency: Has the ability to differentiate into all cell types within 1 particular lineage
• How does a tumor form?

  Cancerous cells divide repeatedly and uncontrollably, forming a tumor

  • Cancers arise due to uncontrolled mitosis

  Cancers start when changes occur in the genes that controlled cell division
• If a mutated gene is the one that causes the cancer it is known as an oncogene

  If a carcinogen causes cancer it is called carciogenic
• Benign tumors: tumors that do not spread from their original site and don't cause cancer

  Malignant tumors: Tumors that spread through the body from their original site, including and destroying other tissues and causes cancer