Question

1. Why do signaling responses that involve changes in proteins already present in the cell occur in milliseconds to seconds, whereas responses that require changes in gene expression require minutes to hours?

Answer 1

Signaling responses that involve changes in proteins already present in the cell occur in milliseconds to seconds, whereas responses that require changes in gene expression require minutes to hours. This is because for a protein modification to occur, the protein and modification enzyme are already present in the cell, it is just that the enzyme needs to be activated. Also, If the pathway modifies a protein that is already present in the cell, its activity is changed immediately, leading to a rapid response.

But, for a response to occur via transcription, translation, protein folding and post translation modifications, it generally takes longer duration of time. If the pathway modifies gene expression, there will be a delay corresponding to the time it takes for the mRNA and protein to be made and for the cellular levels of the protein to be altered sufficiently to invoke a response, which would usually take an hour or more.