Epigenetics

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.

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.