Mitosis

• What enzyme is responsible for separating the two strands of DNA during replication?

  DNA helicase
• How do free nucleotides attach to the template strand during DNA replication?


  Through complementary base pairing
• What is the role of DNA polymerase in DNA replication?


  It joins nucleotides together
• What does it mean that DNA replication is semi-conservative?


  Each new DNA molecule contains one old strand and one new strand
• Where are ribosomes made?

  In the nucleolus
• What is the primary function of ribosomes?


  Protein synthesis
• What is the function of mitochondria in a cell?


  Where aerobic respiration occurs, providing ATP for the cell
• What is a chromosome composed of?


  • Two strands called sister chromatids
  • Joined in the middle by a centromere
• What does each sister chromatid on a chromosome contain?


  Identical genetic information
• Why are chromosomes not visible during Interphase?


  Because the DNA is uncondensed
• What happens to the nucleolus during Interphase?


  The nucleolus is still visible
• What occurs to the nuclear envelope during Interphase?


  The nuclear envelope is still intact
• What happens to centrioles during Interphase?


  They replicate and may be visible
• What are the main events that occur during Prophase?


  • Chromosomes condense
  • Nucleolus disappears
  • Nuclear envelope begins to break down
  • Spindle fibres form
  • Centrioles migrate apart
• What are the main events that occur during Metaphase?


  • Nuclear membrane has broken down
  • Chromosomes align at the equator of the cell
  • Each chromosome is attached to a spindle fibre by its centromere
• What are the main events that occur during Anaphase?


  • Centromere of each chromosome splits
  • One chromatid moves to centrioles at the poles
  • Chromatids are now called chromosomes
• What are the main events that occur during Telophase?


  • Nuclear membranes reform around each group of chromosomes
  • Nucleolus reforms
  • Spindles disappear
  • Chromosomes extend and become invisible
• What is the order of the stages of mitosis?


  Prophase, Metaphase, Anaphase, Telophase
• What is a centromere?


  The center point of a chromosome that holds two sister chromatids together
• What is a centriole?


  Bundles of protein that produce spindle fibres and move to the poles of the cell in prophase
• What are the two methods of cell division?

  Mitosis and meiosis
• What is created through mitosis?


  Two genetically identical daughter cells
• What is created through meiosis?


  Four genetically unique daughter cells
• What is the stage of the cell cycle in which the cell is not dividing?

  Interphase
• What are the main stages of mitosis?


  1. Prophase
  2. Metaphase
  3. Anaphase
  4. Telophase
  5. Cytokinesis
• What are the main events of prophase?

  Nuclear envelope breaks down, chromosomes condense, nucleolus disappears, spindle fibres start to form
• How is prophase different between animals and plants?


  In animals, the centrioles move to the poles of the cell; plants do not have centrioles
• What happens during metaphase?


  Chromosomes line up along the equator, and microtubules attach to centromeres
• What happens during anaphase?


  Sister chromatids are pulled to opposite poles of the cell
• Where does the energy for anaphase come from?


  Mitochondria which surround the spindle fibers
• What happens during telophase?


  Nuclear envelope reforms around each set of chromosomes
• What happens during cytokinesis?


  The cells separate from one another as the membrane pinches in
• What is the name given to cell division in prokaryotes?


  Binary fission
• What happens if the genes controlling cell division are damaged?


  Uncontrolled mitosis can occur
• How do tumours relate to cell division?


  Tumours are caused by uncontrolled cell division
• What is the basic difference between a benign and a malignant tumour?


  A benign tumour grows slowly and is kept in one place, while a malignant tumour grows quickly and spreads
• Why do cells replicate by mitosis?


  To increase the size of tissues or to replace dead or damaged cells
• What factors affect the rate of cell division?

  The environment, growth factors, and genes
• What happens if damaged cells with genetic mutations survive?


  They could clone themselves and form either benign or malignant tumours
• How are tumours linked to cell division?


  Uncontrolled cell division can lead to the formation of tumours