CELL DIVISION
THE CELL CYCLE
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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When DNA damage is repaired.
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When cells are removed from the cell cycle.
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When DNA damage cannot be repaired.
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Detailed explanation-1: -At the cellular level, damaged DNA that is not properly repaired can lead to genomic instability, apoptosis, or senescence, which can greatly affect the organism’s development and ageing process.
Detailed explanation-2: -If the damage cannot be fixed after a critical number of p53 pulses, then p53 is fully activated by further modifications such as phosphorylation at Ser-46 to trigger apoptosis, with its concentration switching to rather high levels. Thus, p53 undergoes a two-phase response in irreparably damaged cells.
Detailed explanation-3: -Apoptosis is a secondary response to DNA damage, with the biological goal of protecting a multicellular organism against a damaged cell. The p53-dependent transcription response can also trigger another secondary response to protect the organism, and this is to enforce the growth arrest of a damaged cell.
Detailed explanation-4: -Apoptosis takes place during G1 Several studies have reported labeling of dying cells with S-phase markers (Herrup and Busser, 1995; Reznikov and van der Kooy, 1995). However, this finding is not conclusive proof of proliferative activity, because uptake may have occurred passively in cells with severely damaged DNA.