Lecture 03

• What are the stages of mitosis referenced in?

  Chromosomes and cytoskeleton
• What is cytokinesis?

  Division of the cytoplasm
• What does cell theory state about living organisms?

  • All living organisms are made of cells
  • Multicellular organisms consist of many cells
  • The cell is the basic structural unit
  • Cells come from pre-existing cells
• What is the life cycle duration of Saccharomyces?

  90-120 minutes
• How long is the life cycle of fibroblasts in culture?

  20 hours
• What is the life cycle duration of hepatocytes?

  Less than 1 year
• What is the role of the cyclin-Cdk complex in the cell cycle?

  • Activated by binding to cyclins
  • Controls progression through cell cycle phases
  • Phosphorylates target proteins
  • Regulates DNA replication, mitosis, and division

  
• How does the eukaryotic cell ensure proper chromosome distribution?

  By keeping replicated chromosomes together
• What do condensins do during cell division?

  They help in chromosome condensation and segregation

  
• What role do microtubules play in cell division?

  They form spindle fibers to move chromatids

  
• What is a kinetochore?

  A protein complex on the centromere

  
• How is the mitotic spindle formed?

  From centrosomes migrating to spindle poles

  
• What happens during prometaphase?

  Nuclear membrane breaks down and microtubules appear
• What occurs during metaphase?

  Sister chromatids line up at the cell equator
• What happens during anaphase?

  Sister chromatids move to the cell ends

  
• What occurs during telophase?

  Spindle fibre break down and nuclear membrane reforms

  
• What is the role of the contractile ring in cytokinesis?

  It splits the cytoplasm
• What protein is involved in the contractile ring during cytokinesis?

  Actin
• What is the overall process of mitosis?

  1. Prophase: Chromosomes condense, spindle forms
  2. Prometaphase: Nuclear membrane breaks down
  3. Metaphase: Chromosomes align at the equator
  4. Anaphase: Sister chromatids separate
  5. Telophase: Nuclear membrane reforms, chromosomes uncoil

  
• What are the key components of the cell cycle control system?

  • Cyclin-Cdk complexes
  • Phosphorylation of target proteins
  • Regulation of cell cycle phases

  
• What are the stages of mitosis with reference to the cytoskeleton?

  • Prophase: Spindle formation
  • Prometaphase: Microtubules connect to kinetochores
  • Metaphase: Chromatids align
  • Anaphase: Chromatids move apart
  • Telophase: Spindle fibres disassemble

  
• What is the significance of the cell cycle in eukaryotic cells?

  • Ensures proper cell division
  • Regulates growth and development
  • Maintains genetic stability