Describe the steps by which the p53 gene responds to DNA damage and/or cellular

Question

Describe the steps by which the p53 gene responds to DNA damage and/or cellular stress to promote cell-cycle arrest and apoptosis. Given that p53 is a recessive gene and is not located on the X chromosome, why would people who inherit just one mutant copy of a recessive tumor-suppressor gene be at higher risk of developing cancer than those without the recessive gene?

Describe the steps by which the p53 gene responds to DNA damage and or cellular stress to promote cell-cycle arrest and apoptosis. Given that p53 is a recessive gene and is not located on the X chromosome, why would people who inherit just one mutant copy of a recessive tumor suppressor gene be at higher risk of developing cancer than those without the recessive gene? Drag the terms on the left to the appropriate blanks on the right to complete the sentences. Not all terms will be used. Reset Help apoptosis When activated the p53 protein initiates followed by and apoptosis. This process involves stimulating transcription of p21, which inhibits the CDKA/cyclin D1 complex. Activated p53 also prevents the cell from initiating the phase. Through a series of steps, BAX homodimers are formed that lead to Individuals who are heterozygous for p53 need only have a mutation in the existing nomal gene to the protection of the p53 cell-cycle arrest protein. lose cell-cycle resuming DNA repair gain CDK1/cyclin D4

Explanation / Answer

When activated, the p53 protein initiates cell cycle arrest followed by DNA repair and apoptosis. This process involves stimulating transcription of p21, which inhibits cyclinD1/CDK4 complex. Activated p53 also prevents the cell from initiating the S phase.Through a series of steps, BAX homodimers are formed that lead to apoptosis . Individuals who are heterozygous for p53 need only have a mutation in the existing normal gene to lose the protection of the p53 protein.

Steps:

1.  p53 arrests the cell cycle at the G1/S and G2/M checkpoints and prevents the cell from entering the S phase.

2. This arrest is carried out by the transcription of p21 gene which goes and inhibits cyclinD1/CDK4 which halts the cell cycle and inhibits the cell's entry to the S phase.

3. p53 also has the ability to instruct a cell to undergo apoptosis. This is done so by the regulation of Bcl2 gene or the BAX gene. Bax protein form homodimers and induce apoptosis by making several cellular changes.

Thus, p53 has a great role to play in the integrity of the genome and hence even one mutated copy is enough to trigger severity.

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