10.1 Flashcards
What is the order and events of each phase?
G0 is the resting phase, it replaces the cell cycle sometimes.
G1 is the first growth phase, the cell grows and needs sufficient resources to progress to the S phase.
S phase is when the DNA is replicated, the DNA has to remain undamaged and errorless to progress to the G2 phase.
G2 phase is the second growth phase, this is when the cell prepares to be divided, it grows to the size of both cells.
M phase is when the cell gets divided.
What are stimulatory and inhibitory proteins?
Stimulatory proteins are ones that progress the cell cycle, they are: Growth factors, which tell the cell to move on to the next phase, cdks, which phosphorylate other proteins so they function and progress the phase, and cyclins, which attach to cdks to make them work. Inhibitory proteins are ones that block the cell from continuing through the cell cycle, one example is p53, which constantly checks for errors in the DNA, and will stop the cell from progressing if any are present, so they can be fixed.
What do proto-oncogenes and tumor suppressor genes do?
Proto-oncogenes keep the cell cycle moving, like accelerating on a gas pedal, and tumor suppressor genes stop or slow down the cell cycle, like brakes.
Why do mutations in proto-oncogenes and tumor suppressor genes lead to cancer?
A mutation in the proto-oncogenes can cause the cell to accelerate too quickly through the cell cycle, and mistakes may not be caught and cancer can develop. A mutation in the tumor suppressor genes causes the “brakes” to stop working, so the cell can freely continue at a very fast pace through the cell cycle, and mistakes in DNA replication can no longer be caught and stopped, so cancer will develop.
