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Flashcards in Control of Gene Expression in Eukaryotes Deck (16)
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Transcription factors

search for promoter and enhancer regions in the DNA



are within 25 basepairs of the transcription start site



are more than 25 base pairs away from the transcription start site.
allows for the control of one gene's expression by multiple signals


Modification of chromatin structure affects

the ability of transcriptional enzymes to access the DNA through histone acetylation (increases accessibility) or DNA methylation (decreases accessibility).


2 domains in Transcription factors

DNA binding domain
activation domain


DNA binding domain

binds to a specific nucleotide sequence in the promoter region or to a DNA response element (a sequence of DNA that binds only to specific transcription factors) to help in the recruitment of transcriptional machinery.


Activation domain

allows for the binding of several transcription factors and other important regulatory proteins, such as RNA polymerase and histone acetylates, which function in the remodeling of the chromatin structure


The large distance between the enhancer and promoter regions for a given gene means

that DNA often must bend into a hairpin loop to bring these elements together spatially



tightly coiled DNA that appears dark under the microscope; its tight coiling makes it inaccessible to the transcription machinery, so these genes are inactive



looser than heterochromatin and appears light under the microscope; the transcription machinery can access the genes of interest, so these genes are active.


Remodeling of the chromatin structures

regulates gene expression levels in the cell


Histone acetylases

proteins involved in chromatin remodeling because they acetylate lysine residues found in the amino terminal tail regions of histone proteins.

Specific patterns of this can lead to increased gene expression levels.


Acetylation of histone proteins

decrease the positive charge on lysine residues and weakens the interaction of the histone with DNA, resulting in an open chromatin conformation that allows for easier access of the transcriptional machinery to the DNA


Histone deacetyleases

proteins that function to remove acetyl groups from histones, which results in a closed chromatin conformation and overall decrease in gene expression levels in the cell


DNA methylation

involved in chromatin remodeling and regulation of gene expression levels in the cell.


DNA methylases

add methyl groups to cytosine and adenine nucleotides; methylation of gene is often linked with the silencing of gene expression.
During development, DNA methylases play an important role in silencing genes that no longer need to be activated.