Control of Gene Expression in Eukaryotes Flashcards

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1
Q

Transcription factors

A

search for promoter and enhancer regions in the DNA

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2
Q

Promotes

A

are within 25 basepairs of the transcription start site

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3
Q

Enhancers

A

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

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4
Q

Modification of chromatin structure affects

A

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

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5
Q

2 domains in Transcription factors

A

DNA binding domain

activation domain

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6
Q

DNA binding domain

A

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.

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7
Q

Activation domain

A

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

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8
Q

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

A

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

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9
Q

Heterochromatin

A

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

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10
Q

Euchromatin

A

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

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11
Q

Remodeling of the chromatin structures

A

regulates gene expression levels in the cell

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12
Q

Histone acetylases

A

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.

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13
Q

Acetylation of histone proteins

A

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

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14
Q

Histone deacetyleases

A

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

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15
Q

DNA methylation

A

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

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16
Q

DNA methylases

A

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.