Cell cycle

• What is the alternative to mitosis mentioned?

  Meiosis
• How do prokaryotic cells replicate?

  By binary fission
• How do viruses replicate?

  Inside host cells by injecting nucleic acid
• What are the main stages of the cell cycle?

  • Interphase (G1, S, G2)
  • Nuclear division (mitosis or meiosis)
  • Cytokinesis (cytoplasm splits)
• What percentage of the cell cycle is interphase?

  About 90% or longer
• What happens during the G1 phase?

  Organelles double and the cell grows
• What occurs during the S phase?

  DNA replication happens
• What is the purpose of the G2 phase?

  Final growth and error checking of DNA
• What are the four key stages of mitosis?

  Prophase, metaphase, anaphase, telophase
• How many rounds of division occur in mitosis?

  One round of division
• What type of cells are produced by mitosis?

  Genetically identical diploid cells
• What occurs during metaphase?

  • Chromosomes align along the equator
  • Spindle fibers attach to chromatids
  • No nucleus is present
• What happens to chromosomes during prophase?

  • Chromosomes condense and become visible
  • Centrioles move to opposite poles
  • Nuclear envelope starts to disintegrate
• What happens during anaphase?

  • Spindle fibers retract, pulling chromatids apart
  • Chromatids move to opposite poles
  • Requires ATP for energy
• What occurs during telophase?

  • Chromosomes become longer and thinner
  • Spindle fibers disintegrate
  • Nuclear envelope reforms
• What is cytokinesis?

  Splitting of the cytoplasm
• What is the mitotic index?

  Ratio of cells in mitosis to total cells
• How do you calculate the mitotic index?

  Divide cells in mitosis by total cells
• What might an exam question specify regarding cells in mitosis?

  To look at only complete cells
• What are the key points to remember about mitosis for exams?

  • Stages: prophase, metaphase, anaphase, telophase
  • Cells produced are diploid and genetically identical
  • Mitosis is for growth and repair
  • Calculate mitotic index as needed
• What is mitosis?

  A type of cell division
• What happens to one cell during mitosis?

  It splits into two cells
• What is the relationship between mitosis and the cell cycle?

  Mitosis is part of the cell cycle
• How long can the cell cycle take in certain mammalian cells?

  Around 24 hours
• What can happen to some cells in the cell cycle?

  They can exit the cell cycle
• What are the two main parts of the cell cycle?

  M phase and interphase
• What occurs during interphase?

  Many processes happen despite appearing inactive
• What is the first stage of interphase called?

  G1 phase
• What happens during the G1 phase?

  The cell replicates organelles
• Why does the cell increase in size during G1 phase?

  To ensure correct size for daughter cells
• What is the S phase responsible for?

  Replication of all chromosomes
• What does the cell do during the G2 phase?

  Replaces energy stores and repairs DNA
• What happens at the end of the G2 phase?

  The cell enters the M phase
• What are the two parts of the mitotic phase?

  Mitosis and cytokinesis
• What occurs during mitosis?

  Chromosomes are separated into two nuclei
• What happens during cytokinesis?

  The cell divides into two
• What is the G naught phase?

  A phase where cells exit the cell cycle
• Why do fully differentiated cells enter G naught?

  They stay there for the rest of their lives
• What are senescent cells?

  Cells that can no longer divide
• Why do some cells enter G naught temporarily?

  They can re-enter the cell cycle later