Ch 7 Cont Section 5 - Control Of Gene Expression In Eukaryotes Flashcards

1
Q

Transcription factors

A

Transcription activating proteins that search the DNA looking for specific DNA binding motifs. Tend to have two recognizable domains: a DNA binding domain and an activation domain.

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2
Q

DNA binding domain

A

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

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3
Q

Activation domain

A

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

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4
Q

Gene amplification.

A

Expression is increased in response to specific signals such as hormones, growth factors and other intercellular conditions. Accomplished through enhancers and gene duplication.

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5
Q

Enhancer

A

Several response elements grouped together. Allows for the control of one gene’s expression by multiple signals

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6
Q

Heterochromatin

A

Tightly coiled DNA inaccessible to the transcription machinery so these genes are inactive

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7
Q

Euchromatin

A

Loose chromatin - transcription machinery can access so this is active

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8
Q

Histone acetylases

A

Coactivators - these proteins are involved in chromatin remodeling - they acetylate lysine residues found in the amino terminal tail regions of histone proteins

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9
Q

Acetylation of histone proteins

A

Decreases positive charge on lysine residues and weakens interaction if histone with dna resulting in open chromatin conformation that allows for easier access of transcriptional machinery to dna

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10
Q

Histone deacetylases

A

Proteins that function to remove acetyl groups from histones which results in closed chromatin conformation and overall decrease in gene expression levels in the cell (gene silencing)

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11
Q

DNA methylation

A

Involved in chromatin remodeling and regulation of gene expression levels in the cell - dna methylases add methyl groups to cytosine and adenine nucleotides; methylation linked with silencing genes which no longer need to be activated. Heterochromatin much more easily methylated

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