Question

Indicate whether each of the following histone modifications adds a negative charge to the histone (A), removes a positive charge from the histone (B), or does neither of these (C). Your answer would be a four-letter string composed of letters A, B, and C only, e.g. CABA.

( ) H3 lysine 9 acetylation
( ) H3 serine 10 phosphorylation
( ) H3 lysine 4 trimethylation
( ) H3 lysine 9 trimethylation

Answer 1

The modifications on H3 histone proteins impact the charge as follows: acetylation makes the protein less positive (A), phosphorylation adds a negative charge (B), and methylation does not affect the charge (C). Hence, for H3 lysine 9 acetylation, serine 10 phosphorylation, lysine 4 trimethylation, and lysine 9 trimethylation, the sequence is ABCC.

Step-by-step explanation:

To determine the impact of various histone modifications on the charge of the histone protein, one must understand the nature of these modifications. Here's how each modification affects histone charge:

• (A) H3 lysine 9 acetylation - Acetylation typically adds an acetyl group to a lysine residue, removing the positive charge and thus making the histone less positive.
• (B) H3 serine 10 phosphorylation - Phosphorylation adds a negatively charged phosphate group, thus it introduces a negative charge.
• (C) H3 lysine 4 trimethylation - Methylation adds a methyl group, which is neutral, so this neither adds nor removes a charge from the histone.
• (C) H3 lysine 9 trimethylation - Similar to lysine 4 trimethylation, this neutrality means no charge is added or removed.

The answer to the question is represented by the four-letter string: ABCC.