Question

Which one of the following modifications occurs both on DNA and protein?

• A. ADP-ribosylation
• B. Methylation
• C. Sumoylation
• D. Ubiquitination

Hint:

Methylation is one of the few modifications that affect both DNA and proteins, regulating gene expression and protein function.

Answer 1

The Correct Option is A

Step 1: Understanding the modifications.
Methylation is a chemical modification that can occur on both DNA and proteins. On DNA, it typically occurs on cytosine residues (in CpG islands), and on proteins, it often occurs on lysine or arginine residues.
Step 2: Analyzing the options.
(A) ADP-ribosylation: Incorrect — This modification typically occurs on proteins, not DNA.
(B) Methylation: Correct — Methylation can occur on both DNA and proteins.
(C) Sumoylation: Incorrect — This primarily affects proteins, not DNA.
(D) Ubiquitination: Incorrect — Ubiquitination typically occurs on proteins and not directly on DNA.
Step 3: Conclusion.
The correct answer is (B) Methylation, as it occurs on both DNA and proteins.