Temperature-sensitive alleles are an example of conditional alleles; at the permissive temperature, the gene has normal function
, whereas at the restrictive temperature, the gene has mutant function. You are studying the E2F pathway and you obtain a temperature-sensitive CDK4 mutant. At the permissive temperature, CDK4 functions normally. At the restrictive temperature, CDK4 is non-functional. Would you expect cells to continue growing or stop dividing when at the restrictive temperature? Explain your answer.
When at the restrictive temperature, we can comfortably expect the cell to stop dividing, whilst continuing to grow
The E2F pathway in a cell is responsible for the transition from the G1 stage of the cell cycle to the S stage. The G1 stage is where a cell grows and expands before the duplication of its DNA.
The S stage stands for synthesis. This is the moment in the cellular cycle in which the DNA of the cell is copied in order to prepare for cellular division.
Therefore, if the transition from G1 to S is blocked by <em><u>temperature restrictions</u></em>, we can expect the cell to continue growing, but <u>not </u>divide.
