Lecture 6 - Control Of Gene Expression: Transcriptional Control Flashcards

1
Q

What does it mean by translation and transcription being coupled in bacteria?

A

They happen in the same place, and as soon as mRNA is transcribed RNA polymerase binds

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2
Q

What differences does bacterial gene expression have from eukaryotic?

A

No nuclear membrane, one cytoplasmic compartment, no histones, coupled transcription and translation

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3
Q

What is the subunit in bacteria called that helps RNA polymerase bind to the promoter?

A

Sigma factor

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4
Q

What determines which DNA strand is transcribed?

A

The polarity of the promoter that orients the polymerase

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5
Q

What determines which DNA strand is transcribed?

A

The polarity of the promoter that orients the polymerase

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6
Q

What regions of bacterial DNA are transcribed?

A

Terminator NOT promoter

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7
Q

What is an operon?

A

Clustered genes of related function eg E.Coli Lac operon

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8
Q

What occurs to operons during transcription and translation?

A

All genes in the operon are transcribed together and translated to give separate proteins per operon

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9
Q

What does the Lac operon do in its default state?

A

When lactose is absent, the Lac l gene produces a repressor that switches the Lac operon off (negative gene regulation)

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10
Q

What occurs to the Lac operon is LACTOSE is present?

A

Lactose binds to the repressor inactivating it, therefore RNA polymerase binds to the Lac operon and lactose is metabolised and transported

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11
Q

What is positive gene regulation of the Lac operon?

A

When glucose AND lactose are present, E.coli uses glucose however when glucose is low, a catabolise activator protein (CAP) is activated by cAMP and attaches to the promoter of the Lac operon to increase affinity of RNA polymerase to increase transcription

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12
Q

What do eukaryotic promoters contain promote the binding of general can transcription factors?

A

sequences such as TATA that occurs -30 bases before the transcription start site helping TBP bind

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13
Q

What are enhancers?

A

Activator proteins that are bound to regulatory DNA sequences that allow for receptors to bind meaning substances such as cortisol can then bind and initiate transcription

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14
Q

What is Epigenetics?

A

The study of changes in organisms caused by the modification of gene expression rather than the alteration of the genetic code

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15
Q

What occurs when DNA is methylated?

A

Gene expression is repressed due to methyl groups binding to C or G bases that if in enhancers or promoters, blocks transcriptional factors

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16
Q

What do DNA methyltransferases do to hemimethylated DNA?

A

Add another methyl mark in activating the DNA since the histones and DNA are tightly wound

17
Q

When does a wave of demethylation occur?

A

After fertilisation

18
Q

In what 4 ways can histones be covalently modified on their N terminal tails?

A

Acetylation, phosphorylation, methylation, ubiquitylation