Lecture 25 Flashcards
Where are the molecules controlling cell cycles located?
Cell cycle-controlling molecules are located in the cell nucleus and cytoplasm.
Explain what a checkpoint is in a cell cycle control system
A checkpoint is a critical stage in the cell cycle where the cell assesses conditions and ensures the accuracy of preceding processes before moving to the next phase, preventing the division of damaged cells.
Describe the process and give an example of the maturation promoting factor
Maturation promoting factor (MPF), like CDK1 and cyclin B, activates the cell’s entry into mitosis during the G2 to M phase transition. After triggering mitosis, MPF is inactivated by cyclin B degradation, facilitating cell cycle progression.
What are the G1 checkpoint and M checkpoint
G1 Checkpoint:
End of G1 phase.
Assesses DNA integrity and external signals.
Decides to enter S phase or exit the cell cycle.
M Checkpoint:
During metaphase in mitosis.
Ensures accurate chromosome attachment and alignment.
Regulates entry into anaphase.
What if the checkpoint is not passed? Explain the process of apoptosis
If a checkpoint is not passed, the cell may undergo apoptosis, involving caspase activation, cell shrinkage, and the formation of apoptotic bodies. This process prevents inflammation and ensures the removal of damaged cells.
What is the growth factor effect on cell division (explain using the experiment example)
Cells cultured without growth factors show minimal division. Introducing growth factors stimulates cell division, demonstrating their crucial role in promoting cell proliferation.
Explain density dependent inhibition and anchorage
Density-Dependent Inhibition:
Cells stop dividing upon contact with other cells, regulating tissue density.
Anchorage Dependence:
Cells need to be anchored to a substrate for proper division, preventing uncontrolled growth in the bloodstream.
