Question

In an eukaryote, a repressor protein may block gene expression by binding to a DNA site called:
A. Operon
B. Histone
C. Enhancer
D. Promoter

Answer 1

Hint: Proteins known as repressors inhibit or suppress gene expression, which is demonstrated by decreased messenger RNA synthesis from the repressed gene. Repressor proteins normally work by attaching to and preventing important DNA sequences in the gene, like the promoter, which is where mRNA production begins.


Complete step by step solution:
The lac operon's transcription is repressed (inhibited) by the lac repressor protein. In order to accomplish this, it binds to the promoter's partially overlapping operator. When bound, the lac repressor gets in the way of RNA polymerase and prevents operon transcription. chromosomes contain a specific kind of protein.
Histones are proteins that attach to DNA, form chromosomes, and regulate gene activity. Enlarge. DNA structure. The majority of DNA is found in a cell's nucleus, where it takes shape as chromosomes. A histone octamer, which has the shape of a spool and is made up of eight histone proteins, surrounds the DNA that makes up each nucleosome. The histone proteins H2A, H2B, H3, and H4 each make up two copies of the histone octamer.
Short regulatory DNA segments known as enhancers aid in establishing the transcriptional program of cells by promoting the transcription of target genes. They are bound by RNA polymerase II, co-regulators, and transcription factors (RNAP II).
Enhancers are traditionally understood to be cis-acting DNA regions that can boost gene transcription. Typically, they operate at a variety of distances from their target promoter and independently of orientation (or promoters). The genes that code for the enzymes needed to break down tetracycline could be expressed without the repressor.
So, option (C) is correct.

Note:
Repressor proteins include lac repressor, which prevents the lac operon in E. coli from being expressed. MetJ, a methionine repressor of the met operon, is an additional. Other molecules, like inducers and corepressors, have an impact on repressor proteins.