4: Cell cycle

• What does the cell theory state about new cells?

  New cells originate by division of pre-existing cells
• What is the parent cell?

  The cell that divides to form new cells
• Why is cell division necessary?

  For development, growth, healing, and reproduction
• What do daughter cells inherit from parent cells?

  Genetic characteristics for the next generation
• What occurs during the cell cycle?

  Cells grow, replicate chromosomes, and divide
• What are the two main phases of the cell cycle?

  Interphase and mitotic phase
• What is interphase in the cell cycle?

  The period between two consecutive divisions
• What are the three sub-phases of interphase?

  G₁, S, and G₂ phases
• What happens during the G₁ phase?

  Cell grows and prepares for DNA replication
• What is the S phase responsible for?

  Replication of the cell's entire genetic material
• What are sister chromatids?

  Two identical copies of a chromosome
• What occurs during the G₂ phase?

  Cell prepares for mitotic phase and accumulates energy
• What is the G₀ phase?

  A resting phase where cells stop dividing
• Which cells typically enter the G₀ phase permanently?

  Neurons that never divide again
• What is the mitotic phase also known as?

  M phase
• What happens to liver and kidney cells in the G₀ phase?

  They enter temporarily and can re-enter the cycle
• How do cancer cells differ from normal cells in the cell cycle?

  Cancer cells divide excessively without control
• What occurs during the mitotic phase?

  The cell divides into daughter cells
• What is a tumour?

  An abnormal mass of cells
• What distinguishes a benign tumour from cancerous tumours?

  Benign tumours consist of normal essential cells
• What are the phases of the cell cycle and their functions?

  • Interphase: Growth and preparation for division
  • G₁: Cell growth and organelle production
  • S: DNA replication
  • G₂: Preparation for mitosis
  • Mitotic phase: Division into daughter cells
• What are the implications of uncontrolled cell division in cancer?

  • Excessive growth of cells
  • Formation of tumours
  • Potential for metastasis
  • Disruption of normal tissue function
• What is the significance of the cell cycle in living organisms?

  • Essential for growth and development
  • Necessary for tissue repair and regeneration
  • Important for reproduction (sexual and asexual)
  • Maintains genetic continuity across generations
• What is a malignant tumour?

  A cancerous tumour that spreads
• What is metastasis in cancer?

  The spread of cancer cells to other parts
• What forms the spindle apparatus during cell division?

  • Cytoskeleton of eukaryotic cells
  • Major component: microtubules
• What is the role of the spindle apparatus during cell division?

  It separates chromatids or chromosomes
• Where are centrioles located in animal cells?

  Near the nucleus
• What happens to centrioles during cell division?

  They duplicate and migrate to opposite poles
• What do centrioles give rise to during cell division?

  Spindle fibres
• How does the spindle apparatus form in plant cells?

  Without centrioles
• What is mitosis?

  Cell division producing two identical daughter cells
• How long does mitosis typically take?

  Less than an hour
• What are the two main stages of mitosis?

  1. Karyokinesis
  2. Cytokinesis
• What is karyokinesis?

  • Division of the nucleus
  • Forms two nuclei in a dividing cell
• What are the phases of karyokinesis?

  1. Prophase
  2. Metaphase
  3. Anaphase
  4. Telophase
• What is chromatin?

  Thin threads of hereditary material
• What happens to chromatin during prophase?

  It condenses into chromosomes
• What is the longest phase of cell division?

  Prophase
• What occurs to chromosomes during prophase?

  Each consists of two chromatids