The expression of a gene located in a tightly coiled region of DNA can be promoted by __________.

• A. the arrival of the RNA polymerase
• B. removal of acetyl groups from histones
• C. methylation of histone tails
• D. demethylation of DNA
• E. histone acetylation

Answer: (E)

Verified step by step guidance

1. Understand that gene expression is influenced by the structure of chromatin, which is DNA wrapped around histone proteins.
2. Recognize that tightly coiled DNA, also known as heterochromatin, is generally less accessible for transcription machinery, such as RNA polymerase.
3. Learn that histone acetylation involves the addition of acetyl groups to histone proteins, which reduces the positive charge on histones and decreases their interaction with the negatively charged DNA.
4. Realize that this acetylation process results in a more relaxed chromatin structure, known as euchromatin, making the DNA more accessible for transcription.
5. Conclude that histone acetylation promotes gene expression by loosening the chromatin structure, allowing transcription factors and RNA polymerase to access the DNA more easily.