Chromatin remodeling is the dynamic modification of chromatin architecture to allow access of condensed genomic DNA to the regulatory transcription machinery proteins, and thereby control gene expression.
What are chromatin remodeling complexes?
Chromatin Remodeling at a Glance Currently, investigators know that chromatin remodelers are large, multiprotein complexes that use the energy of ATP hydrolysis to mobilize and restructure nucleosomes.
How do chromatin remodeling complexes recognize the genes?
The many different remodeling enzymes recognize different histone modifications, DNA structures/sequences and RNA signals that target them to specific genomic loci. To recognize these chromatin signals remodeling complexes have dedicated protein domains, termed reader domains.
What is the function of chromatin remodeling complexes quizlet?
How do chromatin-remodeling complexes work? Chromatin-remodeling complexes use energy from ATP hydrolysis to alter the arrangement of nucleosomes, making the DNA more accessible to other proteins.
How does chromatin-remodeling increase transcriptional initiation?
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.
What role do chromatin remodelers play in eukaryotic gene expression?
What role do chromatin remodelers play in eukaryotic gene expression? Chromatin remodeler enzymes can enzymatically change the distribution or composition of nucleosomes (histone octamers). a eukaryotic cis-acting DNA regulatory sequence to which transacting factors bind and stimulate transcription.
What does the chromatin-remodeling complex expose on the DNA that affects transcription?
There is also evidence that chromatin-remodeling complexes work together with enzymes that alter histones, such as acetyltransferase enzymes (see next section), to change chromatin structure and expose DNA for transcription.
What is meant by the term chromatin-remodeling quizlet?
What is meant by the term chromatin remodeling? Chromatin remodeling includes altering chromatin structure by altering the composition of histones within nucleosomes. Chromatin remodeling includes altering chromatin structure by altering the positioning of nucleosomes with respect to specific DNA sequences.
How does chromatin structure affect gene expression?
DNA is stored in a highly structured complex called chromatin. Epigenetic processes control gene expression by altering chromatin structure (Figure 1). Actively transcribed genes are associated with accessible chromatin regions, while transcriptionally silent genes are found in inaccessible chromatin regions.
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.
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.
What is the function of chromatin quizlet?
The primary functions of chromatin are 1) to package DNA into a smaller volume to fit in the cell, 2) to strengthen the DNA to allow mitosis, 3) to prevent DNA damage, and 4) to control gene expression and DNA replication.
What is the role of chromatin in the regulation of transcription?
In order to activate transcription, some of the specific transcription factors must have the capacity to bind to their binding sites when organized into nucleosomes. As a next step, the chromatin structure of the promoter needs to be decondensed in order to facilitate the binding of the basal transcription machinery.
Why does chromatin compaction affect gene expression quizlet?
When chromatin is condensed, DNA is not accessible for transcription. Acetylation of histone tails reduces the attraction between neighboring nucleosomes, causing chromatin to assume a looser structure and allowing access to the DNA for transcription.
How does histone acetylation affect chromatin structure?
Histone acetylation may affect chromatin structure directly by altering DNA‐histone interactions within and between nucleosomes, thus resulting in a more open higher‐order chromatin structure.
What is DNA methylation?
DNA methylation is a biochemical process where a DNA base, usually cytosine, is enzymatically methylated at the 5-carbon position. An epigenetic modification associated with gene regulation, DNA methylation is of paramount importance to biological health and disease.
What regulates chromatin structure?
Chromatin accessibility is regulated by nucleosome remodeling, utilization of histone variants, DNA methylation, and posttranslational modifications (PTMs). Chromatin remodeling complexes can slide nucleosomes, rotate the DNA helix relative to the nucleosome to expose TF binding sites, or evict nucleosomes.
How a cell can regulate its chromatin structure?
Histone modification and chromatin remodelers have crucial functions in regulating chromatin status, gene activity, and genome stability in the cells. However, these two mechanisms do not work separately; increasing evidence indicate that they interact with each other to regulate chromatin .
What are the two types of chromatin?
Chromatin exists in two forms. One form, called euchromatin, is less condensed and can be transcribed. The second form, called heterochromatin, is highly condensed and is typically not transcribed.
What effect can ATP dependent chromatin-remodeling have on transcription?
ATP-dependent chromatin alteration is accomplished by several multi-subunit chromatin-remodeling complexes that utilize energy derived from ATP hydrolysis to alter nucleosome structure or conformation and, thereby, regulate the access of transcription factors to their cognate DNA binding sites.
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.
How does methylation of histone tails affect the accessibility of DNA?
Methylation and demethylation of histones turns the genes in DNA “off” and “on,” respectively, either by loosening their tails, thereby allowing transcription factors and other proteins to access the DNA, or by encompassing their tails around the DNA, thereby restricting access to the DNA.
What are the major components of chromatin?
Chromatin is a complex of macromolecules composed of DNA, RNA, and protein, which is found inside the nucleus of eukaryotic cells. Chromatin exists in two forms: heterochromatin (condensed) and euchromatin (extended).
Which of the following are the major protein components of chromatin?
The primary protein components of chromatin are histones.
What is a chromatin fiber?
Chromatin fibers are coiled and condensed to form chromosomes. Chromatin makes it possible for many cell processes to occur including DNA replication, transcription, DNA repair, genetic recombination, and cell division.