cell cycle

• What are the key molecular and cellular features of the cell cycle?

  Features of mammalian and yeast cell cycles
• What are the four main phases of mitosis?

  Prophase, Metaphase, Anaphase, Telophase

  
• What is the function of the G1 phase in the cell cycle?

  Cell grows in preparation for mitosis

  
• What occurs during the S phase of the cell cycle?

  DNA is replicated to make identical copies
• What happens in the G2 phase of the cell cycle?

  Cell prepares for mitosis

  
• What is the duration of the mitotic phase (M phase)?

  30 minutes
• What is the G0 phase in the cell cycle?

  Phase when cell is not progressing
• What do cell cycle checkpoints do?

  Prevent transition until current phase is complete

  
• How long does the human cell cycle take?

  Approximately 24 hours
• How long does the yeast cell cycle take?

  90 minutes
• How often do skin cells divide?

  Every 12-24 hours
• How often do liver cells divide?

  Once every 1-2 years
• Do mature nerve cells and muscle cells divide after maturation?

  No, they remain in G0
• What are the key principles and concepts of the cell cycle?

  • Events must occur in proper order
  • Activity of CDKs fluctuates during the cycle
  • CDKs regulated by positive and negative feedback
  • Checkpoint pathways ensure proper progression

  
• What role do CDKs play in the cell cycle?

  They regulate cell cycle progression

  
• How are CDKs regulated?

  By activating and inhibitory phosphorylations

  
• What is the role of cyclins in the cell cycle?

  They activate CDKs at specific stages

  
• How is cyclin synthesis regulated?

  By transcriptional control
• How is cyclin degradation regulated?

  By ubiquitin-mediated proteasome degradation
• What are the different types of CDKs and their roles?

  • G1/S phase CDKs: Trigger entry into the cell cycle
  • S phase CDKs: Active during DNA replication
  • Mitotic CDKs: Active during mitosis

  
• What ensures CDKs are active at the right stage of the cell cycle?

  Multiple regulatory mechanisms

  
• What are the components of checkpoint pathways in the cell cycle?

  • Event sensors
  • Signaling pathway
  • Effector that halts progression

  
• What happens if errors occur during the cell cycle?

  Checkpoint pathways activate repair processes

  
• What is the role of the effector in checkpoint pathways?

  Halts cell cycle progression

  
• How are CDKs regulated?

  By activating and inhibitory phosphorylation

  
• What ensures CDKs are active at the right stage of the cell cycle?

  Multiple mechanisms

  
• What controls cyclin-CDK activity?

  CDK inhibitors

  
• How are cyclin levels primarily regulated?

  By protein synthesis-degradation
• What do different CDKs initiate in the cell cycle?

  Different cell cycle phases

  
• How many total possible substrates do CDKs have in mammalian cells?

  More than 180
• What do checkpoint pathways ensure in the cell cycle?

  Next event does not occur prematurely

  
• What are the components of checkpoint pathways?

  Event sensors, signalling pathway, effector

  
• What does the DNA damage checkpoint monitor?

  DNA synthesis and repair

  
• What happens if DNA synthesis starts before damage is repaired?

  Leads to mutations or cell death

  
• What does the DNA replication checkpoint allow?

  Transition to nuclear division after replication

  
• What does the spindle assembly checkpoint prevent?

  Advancement into anaphase with incorrect spindle assembly

  
• What happens if a kinetochore does not attach to a spindle microtubule?

  Transition to anaphase is inhibited

  
• What initiates telophase in the chromosome segregation checkpoint?

  Proper segregation of chromosomes
• What does the DNA damage response system monitor?

  Cell cycle conditions including DNA replication

  
• Which protein kinases are activated by damaged DNA?

  ATM and ATR