Transcription, RNA syntesis and Pre mRNA Processing

Question 1

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

Answer 1

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

Question 2

What helps create the transcription bubble in prokaryotes and Eukaryotes

Answer 2

Sigma factor in prokaryotes
tfiid in eukaryotes

Question 3

What are the stages of transcription

Answer 3

Initiation Elongation and Transcription

Question 4

what is the physiological inducer for lac operon gene

Answer 4

allolactose

Question 5

What is the other inducer for the lac operon gene

Answer 5

Gratuitous Inducer - IPTG

Question 6

What are the two positive regulations of the lac operon

Answer 6

Presence of lactose- leads to inactiovativation of the repressor

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

Question 7

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

Answer 7

It makes more processive in transcribing the lac operon

Question 8

Which RNA Pol. in Eukaryotes

Question 9

What activates CRP

Answer 9

cAMP

Question 10

What happens before initiation and after initiation that leads to elongation

Answer 10

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

Question 11

How does CRP/ lac repressor ineract with RNA polymerase

Answer 11

Through protein protein interactions

Question 12

How does the lac repressor and CRP identify their binding sites

Answer 12

Through helix-turn-helix motifs

Question 13

What are the two ways of terminating transcription in prokaryotes

Answer 13

Rho-dependent termination a
Rho independent termination

Question 14

How do the two ways of transcription termination in bacteria work

Answer 14

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

Question 15

What makes RNAP processive

Answer 15

The release of the sigma factor

Question 16

Which transcription factor has the ability to identify the TATA box

Answer 16

TFIID

Question 17

WHich transcription factors are the first and last to bind

Answer 17

First to bind-TFIID
Last to bind -TFIIH

Question 18

What enzymatic activities does TFIIH have

Answer 18

Kinase activity
Helicase activity

Question 19

What is the function of the kinase activity of TFIIH

Answer 19

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

Question 20

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

Answer 20

It leads to processivity and promoter clearance of RNAP II

Question 21

Which transcriptiion factor is required for Nucleotide Excision Repair

Answer 21

TFIIH

Question 22

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

Answer 22

TATA box
Initiator(inr)
Downstream Promoter Element
Enhancers

Question 23

What does TFIID consists of

Answer 23

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

Question 24

Nome antibiotic inhibitors of Transcription and how they work

Answer 24

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

Question 25

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

Answer 25

Actinomycin D and Acridine Heparin - inhibits transcription in-vitro

Question 26

WHich drug was used to inhibit Myobacterium tuberculosis

Answer 26

Rifamycin/ Rifampicin

Question 27

How does Microcin J5 work

Answer 27

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

Question 28

How is the lac operon gene regulated

Answer 28

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

Question 29

What is used to classify the RNA pol of Eukaryotes

Answer 29

α-amanitin

Question 30

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

Answer 30

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

Question 31

What are enhancers

Answer 31

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

Question 32

Which proteins are responsible for adding and removing Acetyl to histones

Answer 32

Histone Acetyl Transferases (HAT) And Histone Deacetylase

Question 33

What is the main function of Ubiquitination

Answer 33

It leads to protein degradation

Question 34

What is the triad of phenotypic influences

Answer 34

Genetics Epigenetics Environment

Question 35

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

Answer 35

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

Question 36

Which trasnlation factor does the 5' cap bind to

Answer 36

eIf4E

Question 37

What is the function of the poly(A) tail

Answer 37

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

Question 38

Which spliceosome recognizes the 5' site and the branch site

Answer 38

U1 and U2

Question 39

When is the spliceosome considered to be active

Answer 39

When U1 and U4 leave

Question 40

What is alternative splicing

Answer 40

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

Question 41

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

Answer 41

Splicing regulators, which either bind to Intronic enhancer or intronic repressors, Intronic enhancers include an exon and intronic repressors exlude an exon

Question 42

Give two examples of genes that exhibit alternative splicing

Answer 42

Dscam Gene in Drosophila IGM gene

Question 43

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

Answer 43

5'-RNase P 3'-RNase D

Question 44

What sequence is added to the tRNA after trimming

Answer 44

CCA at the 3' end of the tRNA