Question

Results from genome wide transcript profiling using RNA-seq revealed that from the over 6000 genes encoded by the yeast genome, approximately 800 yeast genes are regulated transcriptionally in a cell cycle specific manner. After looking through this list of 800 cell cycle regulated genes you notice that several genes are missing from the list that you know are required at only a specific phase of the cell cycle.

Which statement(s) could explain how a gene’s transcript could be present throughout the cell cycle, but make a protein active only at one specific phase?

__. a protein could have its activity regulated by post-translational modifications such as phosphorylation

__. a protein might be stable at only one phase of the cell cycle

__. a protein might be present throughout the cell cycle, but its function is only required at one specific phase of the cell cycle

Answer 1

Answer: Phosphorylation is the most common mechanism of regulating protein function and transmitting signals throughout the cell.

Phosphorylation plays a very important roles in the regulation of many cellular processes including cell cycles. Phosphorylation is the most common mechanism of regulating protein function and transmitting signals throughout the cell in which an amino acid residue is phosphorylated by a protein kinase by the addition of a covalently bound phosphate group. Once the activity of protein is completed the protein becomes dephosphorylated again and stops working.