Which statement best describes post-translational modifications?

Which statement best describes post-translational modifications?

• A. Phosphorylation, glycosylation, acetylation, methylation, and more
• B. DNA replication
• C. RNA splicing
• D. Transcription initiation

Answer: (A)

Post-translational modifications are chemical changes added to proteins after they’ve been synthesized. These modifications regulate how a protein works by altering its activity, stability, location inside the cell, and interactions with other molecules. For example, phosphorylation adds phosphate groups to amino acids like serine, threonine, or tyrosine and can turn enzymes on or off; glycosylation attaches sugar chains that affect folding, stability, and where the protein is sent; acetylation and methylation on lysine or arginine residues can change how a protein interacts with others and its role in gene regulation. Because these changes occur after translation and fine-tune protein function in many ways, the statement listing phosphorylation, glycosylation, acetylation, methylation, and more best captures what post-translational modifications are. In contrast, DNA replication, RNA splicing, and transcription initiation are steps in gene expression and RNA processing, not modifications made to a protein after it’s produced.

Post-translational modifications are chemical changes added to proteins after they’ve been synthesized. These modifications regulate how a protein works by altering its activity, stability, location inside the cell, and interactions with other molecules. For example, phosphorylation adds phosphate groups to amino acids like serine, threonine, or tyrosine and can turn enzymes on or off; glycosylation attaches sugar chains that affect folding, stability, and where the protein is sent; acetylation and methylation on lysine or arginine residues can change how a protein interacts with others and its role in gene regulation. Because these changes occur after translation and fine-tune protein function in many ways, the statement listing phosphorylation, glycosylation, acetylation, methylation, and more best captures what post-translational modifications are. In contrast, DNA replication, RNA splicing, and transcription initiation are steps in gene expression and RNA processing, not modifications made to a protein after it’s produced.