cells lect 10

• What is the process behind cell division called?

  Mitosis
• What is the purpose of the cell cycle?

  To produce new cells
• How many daughter cells result from each cell division?

  Two daughter cells
• How does cell division differ in single-celled and multi-cellular organisms?

  Single-celled organisms divide continuously; multi-cellular organisms are controlled
• Where does most cell division occur in the adult human body?

  Bone marrow
• What are post-mitotic cells?

  Cells that never divide
• What are senescent cells?

  Cells that lose the ability to divide
• What is the typical cell cycle duration for a eukaryote cell?

  24 hours
• How long can a hepatocyte live before dividing?

  1-2 years
• How long do neurons and heart cells typically last?

  Never divide
• How quickly can bacteria divide?

  20 minutes
• What occurs during the G1 phase of the cell cycle?

  Cell grows and synthesizes proteins
• What is duplicated during the S phase?

  DNA
• What happens during the G2 phase?

  Cell checks DNA and grows
• What is the fastest stage of the cell cycle?

  M phase
• What occurs during metaphase?

  Chromosomes align at the metaphase plate
• What is the role of the kinetochore?

  Attaches chromosomes to microtubules
• What is cytokinesis?

  Splitting of the cell into two daughter cells
• What are commitment points in the cell cycle?

  Stages where cells decide to proceed
• What is the Hayflick limit?

  Limit on cell divisions in multicellular organisms
• What happens to cells in G0 phase?

  Cells are not actively dividing
• Why do cells have limits on division?

  To reduce cancer risk
• What are telomeres?

  Protective ends of chromosomes
• What is the role of telomerase?

  Rebuilds telomeres in tumor cells
• What are HeLa cells?

  Immortal cell line from Henrietta Lacks
• Why are HeLa cells significant?

  First human cell line used for research
• What do PHE and ATCC provide?

  Repositories for cell lines
• How can immortal cell lines be generated?

  By transforming normal cells with viral genes
• What are the key steps in the cell cycle during mitosis?

  1. G1 phase: Cell growth and protein synthesis
  2. S phase: DNA duplication
  3. G2 phase: DNA check and further growth
  4. M phase: Mitosis and cytokinesis
• What are the two main types of cell death?

  • Necrosis: uncontrolled cell death
  • Apoptosis: programmed cell death
• What are the roles of apoptosis in the body?

  • Embryo development: sculpting tissue
  • Immune system: destroying self-reacting cells
  • Homeostasis: removing old or damaged cells
  • Cancer treatment: inducing apoptosis in cancer cells
• What are the two pathways for triggering apoptosis?

  1. Receptor mediated (extrinsic pathway)
  2. Mitochondria mediated (intrinsic pathway)
• What is the role of caspases in apoptosis?

  • Initiator caspases activate other caspases
  • Effector caspases break down cellular components
• What is the apoptosome and its significance?

  • Multi-protein complex formed during apoptosis
  • Activates initiator caspase 9
• How do Bcl-2 proteins regulate apoptosis?

  • Pro-apoptotic members promote pore formation
  • Anti-apoptotic members block pro-apoptotic actions
• What is the overall significance of apoptosis?

  • Essential for normal health and development
  • Regulates cell death and survival balance