Question

In transcribed DNA, the nucleosomes are altered to facilitate the action of the RNA polymerase in a process known as:

A) Chromosome reworking
B) Chromatin remodelling
C) Chromatin editing
D) Chromosome altering
E) Nucleosomal fasciation

Answer 1

The process where nucleosomes are altered to facilitate RNA polymerase during transcription is known as chromatin remodelling. This involves the dynamic modification of chromosomal structure and includes adding or removing epigenetic tags such as methylation or acetylation.

Step-by-step explanation:

In the process of transcription, nucleosomes are altered to facilitate the action of RNA polymerase. This process is known as chromatin remodelling, wherein the chromosomal structure is modified to either expose or hide segments of DNA to the transcriptional machinery. Nucleosomes can move along the DNA, which can either open up the chromatin to allow RNA polymerase and transcription factors to bind to the DNA and initiate transcription or keep it closed to prevent transcription. Chromatin remodeling is a dynamic process that involves adding or removing epigenetic tags, such as methylation or acetylation, which in turn affect how tightly or loosely the DNA is wound around the histones.

Special protein complexes such as FACT ('facilitates chromatin transcription') play a crucial role in this process by moving histones aside to allow for the transcription machinery to do its work. This also exemplifies the reversible nature of epigenetic changes that are essential for regulating gene expression, and such modifications can have significant implications, as seen in various cancer types where mutations in chromatin remodeling proteins may occur.