Chromatin remodeling is an important mechanism of regulating eukaryotic gene expression, which makes tightly condensed DNA accessible to various regulatory factors, such as transcription factors and components of DNA replication.
What is chromatin remodeling in gene expression?
Chromatin remodeling is the rearrangement of chromatin from a condensed state to a transcriptionally accessible state, allowing transcription factors or other DNA binding proteins to access DNA and control gene expression.
What does the chromatin remodeling complex do?
Various molecules called chromatin remodelers provide the mechanism for modifying chromatin and allowing transcription signals to reach their destinations on the DNA strand.
How does chromatin play a role in gene expression?
In eukaryotes, the tight or loose packaging of the genes in chromatin (DNA plus specific proteins) can control whether the genes can be expressed to form their encoded product. Chromatin is usually not “permissive” but it can be modified in specific areas to open it up for transcription of the genes.
How do chromatin modifications regulate gene expression?
Eukaryotic DNA is packaged and wrapped around proteins known as histones which protect and regulate gene expression. The structure of DNA wrapped around histone octamers is known as chromatin. Chromatin at the first level of its organization appears as a linear array of uniform structural units, nucleosomes.
How do chromatin remodeling complexes work quizlet?
How do chromatin-remodeling complexes work? They use the energy from ATP hydrolysis to alter the arrangement of nucleosomes, rendering certain regions of the DNA more acceible to other proteins. The tails of the core histone proteins can be chemically modified by the covalent addition of what type of chemical group?
How transcription is affected by chromatin remodeling?
As chromatin is condensed into the primary nucleosome structure, DNA becomes less accessible for transcription factors. With the loosening of this chromatin structure, however, transcription machinery is better able to access the genomic DNA, and transcription is thus promoted.
How does histone modification affect chromatin structure and gene expression?
Addition of acetyl groups to particular lysines in histone tails neutralizes the positive charge and loosens the nucleosome’s grip on DNA. This process allows the transcriptional machinery to access the DNA, and genes are active. Other modifications affect transcription in different ways.
Why is histone modification important in gene expression?
Histone modifications do not only function solely by providing dynamic binding platforms for various factors. They can also function to disrupt an interaction between the histone and a chromatin factor.
How does histone modification impact gene expression?
A histone modification is a covalent post-translational modification (PTM) to histone proteins which includes methylation, phosphorylation, acetylation, ubiquitylation, and sumoylation. The PTMs made to histones can impact gene expression by altering chromatin structure or recruiting histone modifiers.
What is the function of ATP dependent chromatin remodeling complexes quizlet?
ATP-dependent chromatin remodeling may effect position of nucleosomes, evict histones, and may replace histones with histone variants. The addition of methyl groups to bases of DNA after DNA synthesis. Inhibits initiation of transcription when occurs near promoter.
How is chromatin remodeled quizlet?
Chromatin Remodeling Complex: slide the nucleosome to a different location or eject it from the DNA or replace it with a new nucleosome that contains a variant histone subunit.
What part of the chromatin fiber does the remodeling complex attach to quizlet?
book: (A) Using the energy of ATP hydrolysis, the remodeling complex is thought to push on the DNA of its bound nucleosome and loosen its attachment to the nucleosome core.
How do histones and DNA interact How does this relate to gene expression?
Histones are subject to modifications that influence their activities. For example, histone acetylation can loosen the tightly wound DNA structure and allow for increased DNA access to transcription factors, thus allowing gene transcription to occur.
What alters gene expression?
Several genetic or epigenetic events can alter gene expression and we assess their importance in multistage carcinogenesis. Mutation and chromosome rearrangement can produce changes in DNA sequence which have been identified in some cancer cells.
What is the function of ATP dependent chromatin remodeling complexes?
ATP dependent remodeling complexes mobilize nucleosomes along DNA, promote the exchange of histones, or completely displace nucleosomes from DNA. These remodeling complexes are often categorized based on the domain organization of their catalytic subunit.
How do histones play a role in gene regulation?
A histone is a protein that provides structural support for a chromosome. Each chromosome contains a long molecule of DNA, which must fit into the cell nucleus. To do that, the DNA wraps around complexes of histone proteins, giving the chromosome a more compact shape.
What epigenetic modifications can occur within the genome to influence gene expression?
There are two types of epigenetic modifications – DNA methylation and histone modifications (16).
How does histone modification alter gene expression quizlet?
How does histone modification alter gene expression? A. Modified histones result in increased DNA methylation, which increases the transcription of genes in that area.
Which of the following is a nucleosome chromatin-remodeling complex?
The only chromatin remodeling complex purified so far is the NuRD complex that couples ATP dependent nucleosome remodeling with histone deacetylation. The transcription repressive ability of the complex has been studied in various genes involved in differentiation and development of C.
How does methylation of histone tails affect the accessibility of DNA quizlet?
Methylation of histone tails in chromatin can promote condensation of the chromatin. Acetylation of histone tails in chromatin allows access to DNA for transcription. One of the mechanisms by which eukaryotes regulate gene expression is through modifications to chromatin structure.
What is the name of the protein that binds the two separated DNA strands to keep them from base pairing again before they can be replicated?
FEEDBACK: As a replication fork travels along the chromosome, the helicase pries apart the two strands of the double-helix. Single-strand binding protein holds these two strands apart and keeps them from reforming base pairs by binding to the single-stranded DNA.
What allows only certain genes to be expressed in certain types of cells?
In eukaryotes, what allows only certain genes to be expressed in certain types of cells? The set of regulatory transcription factors present in a particular cell, not differences in in DNA sequence, are largely responsible for which genes are expressed.
Why does DNA need to be tightly packed?
DNA packaging helps the DNA to fit well within the small size of a cell. It also facilitates the easy separation of the correct chromosomes during cell division. Due to highly packed DNA, it is easy to turn genes on or off as per requirement.
Which of the following are the major protein components of chromatin?
The primary protein components of chromatin are histones that help to organize DNA into “bead-like” structures called nucleosomes by providing a base on which the DNA can be wrapped around. A nucleosome consists of 147 base pairs of DNA that is wrapped around a set of 8 histones called an octomer.