Cell cycle

• What are kinases involved in cell cycle regulation activated by?

  Binding to checkpoint proteins called cyclins
• What forms a cyclin-dependent kinase (CDK) complex?

  Binding of the right cyclin to the appropriate kinase
• What is the role of CDK complexes in the cell cycle?

  They catalyze the activation of key cell-cycle proteins by phosphorylation
• How do enzymes signal the cell to move on to the next phase in the cycle?

  By breaking down cyclins when they aren't needed
• What is cancer defined as?

  A group of many different diseases caused by uncontrolled cell division
• What is a benign tumor?

  A tumor that can stop growing and doesn't travel to other locations in the body
• What characterizes a malignant tumor?

  A tumor that continues to grow and can spread to other locations in the body
• What causes tumors to form?

  Damage or spontaneous mutation of genes that regulate the cell cycle
• What happens if there is overexpression of a cyclin due to mutation?

  It disrupts cell cycle regulation, potentially leading to tumor formation
• How can CDKs be targeted in cancer treatment?

  By using chemical inhibitors to reduce their activity
• What is the G1 checkpoint in the cell cycle?

  A checkpoint before the cell enters the S phase to assess requirements
• What does the G2 checkpoint verify?

  Whether DNA has been replicated without errors
• What is the spindle assembly checkpoint?

  A checkpoint during mitosis where chromosomes must be attached to spindles
• What is cytokinesis?

  The process when the cytoplasm divides to produce two cells
• What happens during interphase?

  Cells prepare for division and produce enzymes or hormones
• What is the role of cyclins in the cell cycle?

  Cyclins build up and attach to CDKs to control the cell cycle
• What is phosphorylation in the context of the cell cycle?

  The addition of a phosphate group to a protein by kinases
• How does phosphorylation affect checkpoint proteins?

  It changes their tertiary structure and activates them
• What is the significance of DNA checking during the cell cycle?

  To prevent mutations that may lead to cancer
• What happens to most normal cells after a limited number of divisions?

  They become senescent and stop dividing
• What can stimulate some cells to re-enter the cell cycle after entering G0 phase?

  Signals from the immune response, such as in lymphocytes
• What are checkpoints in the cell cycle?

  Control mechanisms that verify processes at each stage of the cell cycle
• What is the main purpose of the cell cycle?

  To allow one parent cell to divide and produce two daughter cells
• What is the difference between mitosis and interphase?

  Mitosis is the division of the nucleus, while interphase is preparation for division
• What happens if DNA is not checked during the cell cycle?

  Mutations may occur, causing the new cell to not function properly
• What are the two main phases of the cell cycle in eukaryotic cells?

  Interphase and mitotic phase
• What are the stages of interphase?

  1. G1 phase: Cell growth and organelle synthesis
  2. S phase: DNA replication
  3. G2 phase: Preparation for mitosis
• What are the consequences of mutations in genes regulating the cell cycle?

  • Can lead to uncontrolled cell division
  • May result in tumor formation
  • Can cause cancer
• What are the roles of cyclin-dependent kinases (CDKs) in the cell cycle?

  • Activate proteins by phosphorylation
  • Control progression through the cell cycle
  • Work in conjunction with cyclins
• What are the main checkpoints in the cell cycle?

  1. G1 checkpoint: Before S phase
  2. G2 checkpoint: Before mitotic phase
  3. Spindle assembly checkpoint: During mitosis
• What happens during the mitotic phase?

  • Mitosis: Division of the nucleus
  • Cytokinesis: Division of the cytoplasm
• What is the significance of the G0 phase in the cell cycle?

  • Cells may exit the cycle temporarily or permanently
  • Some cells can be stimulated to re-enter the cycle
  • Important for specialized functions