CELL DIVISION
THE CELL CYCLE
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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p53 gene
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cyclins
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thyroid hormones
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mutagens
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Detailed explanation-1: -p53, the Cellular Gatekeeper for Growth and Division: Cell.
Detailed explanation-2: -Two groups of proteins, called cyclins and cyclin-dependent kinases (Cdks), are responsible for the progress of the cell through the various checkpoints. The levels of the four cyclin proteins fluctuate throughout the cell cycle in a predictable pattern (Figure).
Detailed explanation-3: -Key Points Negative regulator molecules (Rb, p53, and p21) act primarily at the G1 checkpoint and prevent the cell from moving forward to division until damaged DNA is repaired.
Detailed explanation-4: -Cell cycle progression is regulated in part by the sequential activity of various cyclins. The cyclins are regulatory subunits that bind, activate and provide substrate specificity for their catalytic partner serine-threonine kinases, collectively called cyclin-dependent kinases (Cdks) (reviewed in refs. 8 and 9).