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 is the mechanism of action of chromatin remodeling complexes quizlet?
What is one mechanism by which chromatin-remodeling complexes reposition nucleosomes? They promote nucleosome disassembly and reassembly at another site within the chromatin. They change the conformation of DNA and/or nucleosomes so that DNA that is bound to nucleosomes assumes a more exposed conformation.
What is one mechanism by which chromatin remodeling complexes reposition nucleosomes?
What is one mechanism by which chromatin-remodeling complexes reposition nucleosomes? They directly promote histone acetylation that allows chromatin remodeling. They promote nucleosome disassembly and reassembly at another site within the chromatin.
Which is a form of chromatin remodeling?
For example, prior to transcription in yeast, one of the major types of chromatin remodeling machines, called the SWI/SNF and SAGA histone acetylase complex, is recruited to the yeast HO gene promoter by the SWI5 activator.
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 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.
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.
Are chromatin remodeling complexes Atpases?
All of the ATP-dependent chromatin-remodeling complexes contain an ATPase subunit that belongs to the SNF2 superfamily of proteins. Based on the identity of this subunit, they have been classified into two main groups, the SWI2/SNF2 group and the imitation SWI (ISWI) group (25).
How are histones modified?
At least nine different types of histone modifications have been discovered. Acetylation, methylation, phosphorylation, and ubiquitylation are the most well-understood, while GlcNAcylation, citrullination, krotonilation, and isomerization are more recent discoveries that have yet to be thoroughly investigated.
What does histone code refer to?
 The “histone code” is a hypothesis which states that DNA transcription is largely regulated by post-translational modifications to these histone proteins.  Through these mechanisms, a person’s phenotype can change without changing their underlying genetic makeup, controlling gene expression.
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 is the difference between levels of transcription of chromatin in the open versus closed conformation?
What is the difference between levels of transcription of chromatin in the open versus closed conformation? Transcription is high when in the open conformation and low when in the closed conformation.
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 the most highly condensed form of chromatin?
Heterochromatin is more condensed than euchromatin. Typically, the more condensed chromatin is, the less accessible it is by transcription factors and polymerases. The dynamic nature of chromatin is regulated by enzymes.
What is the difference between acetylation and methylation?
Acetylation and methylation are two types of chemical reactions. Both of them are used to add a chemical group to a chemical compound. Acetylation is the process of adding an acetyl group, forming an acetylated compound. Methylation is the process of adding a methyl group, forming a methylated compound.
Is histone modification the same as acetylation?
A schematic diagram of histone modification. Acetyl-CoA is a source and co-factor of acetylation. Histone acetylation occurs at lysine residues and it increases gene expression in general. (B) Histone methylation: Methylation is catalyzed by histone methyltransferase. Histone demethylase reverses methylation.
What is DNA methylation and histone modification?
Both DNA methylation and histone modification are involved in establishing patterns of gene repression during development. Certain forms of histone methylation cause local formation of heterochromatin, which is readily reversible, whereas DNA methylation leads to stable long-term repression.
What are the 5 major types of histones?
Histones are highly conserved basic proteins which associate with DNA with a definite stoichiometry to constitute the ‘nucleosome’ that are essential for the packaging of the genomic DNA into compact structures. There are 5 types of histones namely H2A, H2B, H3, H4 and H1 linker histone.
How many histones are in a nucleosome?
Each nucleosome is composed of a little less than two turns of DNA wrapped around a set of eight proteins called histones, which are known as a histone octamer.
Are introns non coding?
Introns are noncoding sections of an RNA transcript, or the DNA encoding it, that are spliced out before the RNA molecule is translated into a protein. The sections of DNA (or RNA) that code for proteins are called exons.
What binds Okazaki fragments?
On the lagging strand, DNA synthesis restarts many times as the helix unwinds, resulting in many short fragments called “Okazaki fragments.” DNA ligase joins the Okazaki fragments together into a single DNA molecule.
What is the main function of the TATA binding protein?
The TBP gene provides instructions for making a protein called the TATA box binding protein. This protein is active in cells and tissues throughout the body, where it plays an essential role in regulating the activity of most genes.