Question

Chromatin remodeling refers to the process by which

a) methylation occurs in CpG islands.
b) nucleosomes are repositioned to expose different stretches of DNA to the nuclear environment.
c) DNA strands are ""unzipped"" to allow access to the proteins that carry out transcription.
d) mutations change DNA structure and therefore chromatin structure.

Answer 1

Chromatin remodeling is the process where nucleosomes are moved and histones are chemically modified to expose or shield DNA in the nucleus, regulating gene expression.

Step-by-step explanation:

Chromatin remodeling refers to the process by which nucleosomes are repositioned to expose different stretches of DNA to the nuclear environment. This remodeling allows for specific genes to be accessed by transcription machinery when those genes need to be expressed. It involves the repositioning and chemical modification of histone proteins and DNA.

Specifically, histone acetylation and methylation can lead to the unwinding of nucleosomes, thus making the underlying DNA accessible for transcription. Alternatively, de-acetylation and demethylation can condense the chromatin, thereby silencing genes. These modifications are part of an intricate regulation system that ensures genes are expressed at the right time and in the right cells.