4.7: Regulation of the Cell Cycle Flashcards
What occurs at the G1 checkpoint?
At the end of the G1 phase where the cell is growing, the checkpoint makes sure that there are enough nutrients, the cell size is correct, the growth factors are there, and the DNA is not damaged.
What occurs at the G2 checkpoint?
At the end of G2, where the cell was preparing for M phase, they check that DNA has been replicated and that the DNA is not damaged.
What are cyclins? What are CdKs? How do these two interact to allow passage of the G2 checkpoint?
Cyclins are proteins that help regulate the cell cycle. They are produced to make the cell cycle move forward, while they are degraded when the cell cycle needs to be inhibited. There are specific cyclins for each part of the cell cycle. These cyclins activate CdKs, which are enzymes that phosphorylate substrates to promote the cell cycle to continue. The cyclin would be produced and then bind to the cdk, which would lead to phosphorylation and a continuation of the cell cycle.
What occurs at the M checkpoint? What happens if the cell prematurely bypasses this checkpoint?
After Metaphase and before anaphase, there is a checkpoint to make sure that the spindle fibers are attached correctly. If this check does not occur, one cell could end up with more chromosomes than the other.
What process allows for the passage of the M checkpoint?
MPF production formed cdk enzymes and by cyclins being built up and degraded. The most amount of cyclins occurs when the MPF is needed at the end of G2 and before M.
Identify three causes of cancer. How does each affect the cell cycle?
The DNA code is altered so that the function of the protein is different, if the genes regulating the cell cycle are mutated and cant regulate, and an inactive tumor suppressor gene. The cell cycle would keep on going, so the cells would divide uncontrollably.
What is an oncogene?
It is a gene that codes for cancerous cells.
What is a proto-oncogene?
It helps to promote cell growth.
How do the proto-oncogenes cause cancer?
If it mutates into an oncogene, it can cause the cell cycle to continually repeat and divide forever.
What is a tumor suppressor gene?
They help to regulate the cell cycle.
How do the tumor-suppressor genes cause cancer?
If mutated, they could cause unregulated cell division, or cancer.
What causes apoptosis?
If the DNA is damaged, it will die.
