Exam III Review control of transcription initiation chapter 16 Flashcards Preview

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Flashcards in Exam III Review control of transcription initiation chapter 16 Deck (49)
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1

Promoters

Regulatory regions for genes transcribed in a cell type specific manner, always very close to the genes protein coding region. Upstream.

2

Tata box

Part of the promoter upstream of the transcription initiation site binding of RNA polymerase occurs here, An initiation box consisting of roughly 7 nucleotide sequence T a T a (a or T) a (A or T), Allows basal level of transcription

3

Enhancer

A regulatory site that can be quite distant – up to 10,000's nucleotides away from the promoter, can augment or repress Basal levels of transcription. A single _______ may have multiple binding sites for different transcription factors. Maybe located either five prime or three prime to the transcription start site

4

Sequence specific DNA binding proteins that influence transcription (basal factors, activators, or repressors)

Transcription factor

5

Tata box binding protein, assists in the binding of RNA polymerase II to the promoter

Basal transcription factor TBP

6

Tata box binding protein associated factor recruited by TBP, assists in the binding of RNA polymerase two

Basil transcription factor TAF (Tbp – associated factors)

7

Transcription factors that bind to enhancers to increase transcriptional activity by interacting directly or indirectly with Basal factors at the promoter. Responsible for much of the variation in levels of transcription of different genes.

Activators

8

The structural domain with in an activator protein which mediates binding to enhancer DNA, which interact with other proteins to activate transcription

DNA – binding domain

9

DNA-binding motifs found in activators

DNA binding domain helix loop helix

10

DNA-binding structure found mainly in eukaryotic activator proteins

Zinc fingers

11

DNA-binding structure found mainly in prokaryotes Activator proteins for example the lack repressor

Helix turn helix

12

Part of an activator that binds to DNA, binds to either identical (homodimer) or non-identical heterodimer subunits

Dimerization domain

13

A helix with Leucines at regular intervals, June – June homodimers May interact, June – fos heterodimers may interact. Both are motifs found in activator proteins

Leucine zipper dimerization domain

14

Eukaryotic transcription factors that bind specific DNA sites near a gene and prevent the initiation of transcription of the gene by recruiting call repressor proteins that either prevent the RNA polymerase II complex from finding the promoter or modify histones to close chromatin structure

Repressor

15

Indirect repression. A protein can bind the activation domain of an activator bound to an enhancer and thereby prevent the activator from functioning

Quenching

16

Part of the activator protein that binds to other proteins

Activation domain

17

Competition due to overlaping binding sites, quenching, (repressor blocks activation domain) cytoplasmic sequestration, heterodimerization

Ways and indirect repressor can interfere with the function of an activator

18

DNA sequences located between a promoter and an enhancer that block the enhancer from activating transcription from that promoter

Insulators

19

Binds insulators and facilitates the formation of DNA loops

Ccctc binding factor CTCF

20

One chromatin is isolated from the cell nuclei. Two DNA and proteins are chemically cross-linked wig formaldehyde. Three DNA is fragmented by sonication. Four antibody specific to the protein of interest is used. Five DNA to which protein was bound is purified and sequenced.

Chromatin immunoprecipitation-sequencing Chip-seq)

21

Beyond genetics specifically beyond the nucleotide sequence of DNA (modifications)

Epigenetics

22

A methyl group is added to a cytosine base that is followed by a guanine by DNA methyl transferases. Control of transcription.

DNA methylation

23

Regions with a high concentration of CPG dinucleotides

CPG islands

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When a cpg island near a promoter is unmethylated, the gene is transcriptionally active. In the absence of a transcriptional activator, the CPG Island becomes methylated. Methyl CPG binding proteins bind and close the chromatin structure.

DNA methylation at cpg islands silences gene expression

25

Caused by a loss of function mutations in meCPg (methyl CPG binding protein) gene on the X chromosome.

Rhett syndrome

26

Long term repression through DNA methylation

Silencing

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Expression of an allele depends on the parent that transmits it. Methylation at imprinting control regions ICRs silences Jean expression.

Genomic imprinting

28

Paternal allele is silence, maternal allele is expressed

Paternally imprinted

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Maternal allele is silenced, paternal allele is expressed

Maternally imprinted

30

Deletion on a chromosome 15 passed from mother

Angelman syndrome