cell cycle regulation

• what is the role of external signals such as mitogen

  Regulate the cell cycle
• What type of signals regulate cell divison

  External and intenal.
• What are external signals

  Produced by other cells
• What are internal signals

  Produced by a cell to regulate itself.
• where are internal signals found

  Cytoplasm
• What type of signal are mitogens

  External
• What type of signal are cyclin dependant kinases

  Internal
• What do mitogens cause

  Production of S phase cyclins
• What happens if mitogens are not produce or anti-mitogens are produced

  S phase cyclins are not produced so the cell cannot progress through the G1 checkpoint. The cell will enter G0.
• What is G0 called

  Quiescence.
• What is the other name for mitogens

  growth factors
• What action do mitogens use to promote s phase cyclin production

  Signal transduction
• Where are the mitogen receptors

  Plasma membrane
• How are internal signals stimulated

  Using external signals such as mitogens
• Where is the G1 checkpoint

  Before S phase
• Where is the G2 checkpoint

  Before Mitosis
• What are the 3 checkpoints in the cell cycle

  G1, G2, Metaphase.
• What is the name for the metaphase checkpoint

  Spindle assembly checkpoint [SAC]
• Where is the spindle assembly checkpoint

  During metaphase
• Describe the role of the G1 checkpoint

  Determines if the cell size is suitable and if it has received external signals.
• Desecribe the role of the G2 checkpoint

  Determines if the cell size is suitable. If the DNA has replicated.
• Describe the role of the SAC

  Determines if all the chromosomes are attached to the spindles.
• What are the two molecules responsible for the G1 and G2 checkpoints

  Cyclin dependant kinases and cyclins.
• What is a promoting factor

  Cyclin dependant kinases and cyclins.
• What is the G1 promoting factor called

  SPF
• What is the G2 promoting factor called

  MPF
• How do promoting factors work in cell cycle checkpoints

  Phosphorylates proteins and activates them. Allowing the cell to progress to the next phase.
• What is the MPF made of

  cyclin B and Cyclin dependant kinase 1
• What is the SPF promoting factor made of

  Cyclin e and cyclin dependant kinase 2
• What changes to regulate the cell cycle

  An increase in cyclins
• How do cylin levels affect Cdk's

  Increase their activity but the expression levels of Cdk's is constant.
• How are cyclins degraded

  Ubiquitination and proteasomal degradation.
• When are cyclins degraded

  After mitosis
• What is the internal regulator for the SAC called

  Anaphase promoting complex
• What is the correct alignment for the metaphase plate

  Kinetochores attached to both sides of the chromosome
• Describe how the SAC works

  Cohesion wraps around the chromosomes to prevent them from separating early. APC is activated by the SAC. APC causes ubiquitination of cohesion. Anaphase is stimulated, and the chromosomes can separate.
• What type of molecule is cohesion

  Protein