Transcription, RNA syntesis and Pre mRNA Processing Flashcards

1
Q

What genes make up the lac operon and what do they code for

A

LacZ= β-galactosidase
LacY= lactose permease
LacA=transacetylase

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2
Q

What helps create the transcription bubble in prokaryotes and Eukaryotes

A

Sigma factor in prokaryotes
tfiid in eukaryotes

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3
Q

What are the stages of transcription

A

Initiation Elongation and Transcription

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4
Q

what is the physiological inducer for lac operon gene

A

allolactose

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5
Q

What is the other inducer for the lac operon gene

A

Gratuitous Inducer - IPTG

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6
Q

What are the two positive regulations of the lac operon

A

Presence of lactose- leads to inactiovativation of the repressor

Absence of glucose- results in the activation of an activator called CRP

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7
Q

What is the function of CRP/CAP in the regulation of the lac operon

A

It makes more processive in transcribing the lac operon

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8
Q

Which RNA Pol. in Eukaryotes

A
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9
Q

What activates CRP

A

cAMP

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10
Q

What happens before initiation and after initiation that leads to elongation

A

Abortive transcription and then release of sigma factor which leads to elongation

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11
Q

How does CRP/ lac repressor ineract with RNA polymerase

A

Through protein protein interactions

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12
Q

How does the lac repressor and CRP identify their binding sites

A

Through helix-turn-helix motifs

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13
Q

What are the two ways of terminating transcription in prokaryotes

A

Rho-dependent termination a
Rho independent termination

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14
Q

How do the two ways of transcription termination in bacteria work

A

Rho dependent depend on Rho which has helicase activity and removes the RNA strand

Rho independents depend on signal/ termination sequence Which is a GC inverted repeat followed by an AT-rich region, G forms base pair with C forms the hairpin structure forcing the polymerase to release the RNA

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15
Q

What makes RNAP processive

A

The release of the sigma factor

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16
Q

Which transcription factor has the ability to identify the TATA box

A

TFIID

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17
Q

WHich transcription factors are the first and last to bind

A

First to bind-TFIID
Last to bind -TFIIH

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18
Q

What enzymatic activities does TFIIH have

A

Kinase activity
Helicase activity

19
Q

What is the function of the kinase activity of TFIIH

A

Add phosphate to the Carboxy terminal domain of of RNA polymerase II, increase processivity and promoter clearance In Eukaryotes

20
Q

WHat is the role of adding phosphate to the CArboxyl terminal domain of the ribosome

A

It leads to processivity and promoter clearance of RNAP II

21
Q

Which transcriptiion factor is required for Nucleotide Excision Repair

A

TFIIH

22
Q

What can you find at the promoter region of a class II gene

A

TATA box
Initiator(inr)
Downstream Promoter Element
Enhancers

23
Q

What does TFIID consists of

A

Consists of TBP(TATA box binding proteins) + multiple TAFs(TATA associated factors)

24
Q

Nome antibiotic inhibitors of Transcription and how they work

A

Rifampicin-
1. binds to β subunit and inhibits initiation
2. binds to the first two nucleotides and prevents the addition of the third nucleotides , prevents the abortive cycle

Streptoglydigin- binds to the β subunit and inhibits elongation

25
Q

Name two inhibitors of transcription that affect both bacteria and eukaryotes and how they work

A

Actinomycin D and Acridine
Heparin - inhibits transcription in-vitro

26
Q

WHich drug was used to inhibit Myobacterium tuberculosis

A

Rifamycin/ Rifampicin

27
Q

How does Microcin J5 work

A

Blocks nucleotide channels which blocks the source of nucleotides for transcription mrna synthesis

28
Q

How is the lac operon gene regulated

A

The repressor binds to the operater region which prevents promoter clearance to transcribe the lac operon when theres presence of glucose
But with the absence of glucose an inducer binds to the repressor which prevents its binding

29
Q

What is used to classify the RNA pol of Eukaryotes

A

α-amanitin

30
Q

What usually constitue the Promoter region of a Class II gene in eukaryotes

A

The core promoter - The TATA box
-The initiator(inr)
-The downsream promoter region(DPE)
And Enhancers

31
Q

What are enhancers

A

Theyre usually a collection of binding sites for several regulatory factors, and play a role in gene expression and epigenetics

32
Q

Which proteins are responsible for adding and removing Acetyl to histones

A

Histone Acetyl Transferases (HAT)
And
Histone Deacetylase

33
Q

What is the main function of Ubiquitination

A

It leads to protein degradation

34
Q

What is the triad of phenotypic influences

A

Genetics
Epigenetics
Environment

35
Q

What is the function of the 5’ capping of the mRNA

A

For recognition of the mRNA by the Ribosome
And for rendering the 5’ end of the mRNA resistant to exonuclease activity

36
Q

Which trasnlation factor does the 5’ cap bind to

A

eIf4E

37
Q

What is the function of the poly(A) tail

A

Prevents 3’ to 5’ exonucleases from degrading the mRNA
Facilitates mRNA exportation out of the nucleus
Facilitates Translation

38
Q

Which spliceosome recognizes the 5’ site and the branch site

A

U1 and U2

39
Q

When is the spliceosome considered to be active

A

When U1 and U4 leave

40
Q

What is alternative splicing

A

It is the different ways of joining exons to create different mRNA

41
Q

In alternative splicing what determines if an exon is skipped or not

A

Splicing regulators, which either bind to Intronic enhancer or intronic repressors,

Intronic enhancers include an exon and intronic repressors exlude an exon

42
Q

Give two examples of genes that exhibit alternative splicing

A

Dscam Gene in Drosophila
IGM gene

43
Q

What trimming the 5’ end and 3’end of a primary tRNA

A

5’-RNase P
3’-RNase D

44
Q

What sequence is added to the tRNA after trimming

A

CCA at the 3’ end of the tRNA