CELL STRUCTURES AND FUNCTION
CELL CYCLE
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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G2
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S
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M
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G1
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Detailed explanation-1: -This checkpoint, also called the restriction checkpoint, takes place between the G1 and the S phase. The cell verifies that it is large enough to divide, that its DNA is intact, and if there is enough access to nutrients and stimulating growth factors.
Detailed explanation-2: -At the G1 checkpoint, cells decide whether or not to proceed with division based on factors such as: Cell size. Nutrients. Growth factors.
Detailed explanation-3: -G1 (restriction) checkpoint. The G1 checkpoint, also known as the restriction point in mammalian cells and the start point in yeast, is the point at which the cell becomes committed to entering the cell cycle.
Detailed explanation-4: -For example, the G1 checkpoint ensures that the size of the cell is large enough to progress into the S phase and checks for the presence of DNA damage [26].
Detailed explanation-5: -This unleashes cyclin E-CDK2 and cyclin A-CDK2 activity, allowing further RB phosphorylation, exit from G1 and entry into S phase. The G1/S checkpoint is activated upon detection of DNA damage.