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FUN > 9. Transcription and Regulation of Gene Expression > Flashcards

9. Transcription and Regulation of Gene Expression Flashcards

1
Q

What is gene expression?

A

Manufacturing the corresponding protein via the processes of transcription and translation

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2
Q

Functions of RNA

A

Copying of genetic information from DNA
Formation of ribosomes
Assemble new polypeptides

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3
Q

What are promoters?

A

Regions of DNA upstream of the transcription start site which lead to the initiation of transcription

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4
Q

What is a basal promoter?

A

Bound onto by RNA polymerase 2 and basal transcription factors

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5
Q

What are enhancer elements?

A

Recognised by transcription factors

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6
Q

What are the two types of basal elements?

A 
TATA box
CCAT box (needs help of cofactor)
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7
Q

What is transcription?

A

Process by which the information in a strand of DNA is copied into a new molecule of mRNA

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8
Q

What happens in initiation?

A

RNA Pol 2 binds to DNA and unwinds a 17-18 base pair segment of the promoter

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9
Q

What happens in elongation?

A

RNA Pol 2 moves along the template synthesising RNA until it reaches the terminator region

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10
Q

What is the transcription bubble?

A

Unwound area of DNA under the RNA Pol 2

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11
Q

What happens in termination?

A

Transcription continues beyond the protein coding region to the 3’UTR
Most precursors have a polyadenylation sequence
Endonuclease is recruited and cuts mRNA 20 bases downstream from the sequence

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12
Q

What happens in 5’ capping of mRNA precursors?

A

Addition of 7-methyl-guanosine residue to 5’ end of mRNA
Catalysed by guanylyltransferase
Methylated by methyltransferase enzyme

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13
Q

What is the function of 5’ capping?

A

Protection of mRNA from degradation by exonucleases
Promote nuclear export
Aids recognition by translational machinery

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14
Q

Which enzyme adds the 3’ polyadenylation tail to the transcript?

A

Poly(A) Polymerase

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15
Q

How does the polyadenylation tail contribute to mRNA stability?

A

Tail is gradually shortened over lifetime of mRNA

Prevents exons being degraded

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16
Q

What carries out splicing?

A

Spliceosome

Large complex of RNA and protein

17
Q

How do small nuclear RiboNucleoProteins (snRNPs) facilitate splicing?

A

By recognising and interacting with specific sequences at each end of the intron
Cutting and rejoining the RNA sequence

18
Q

What is constitutive gene expression?

A

Always on

Level of expression determined by how many binding sites and how much of transcription factor

19
Q

What is inducible gene expression?

A

Turned on when necessary
Determine tissue specificity
Controlled by transcription factors

20
Q

What determines the rate of transcription?

A

Number of binding sites for that transcription factor in a promoter

21
Q

What is the function of miRNA?

A

Down regulate gene expression

FUN (46 decks)

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