Transcription

Question 1

What is at the 5’ end and 3’ end?

Answer 1

5’ end has phosphate group
3’ end has -OH group

Question 2

What does RNA polymerase do?

Answer 2

RNA polymerase is an enzyme that splits DNA in middle and uses template to make RNA then joins DNA again and lets it go, while a newly formed RNA strand leaves it

Question 3

How does RNA grow?

Answer 3

RNA (like DNA) goes 5’ to 3’

RNA Polymerase (doesn’t need a primer) catalyses linkage of ribonucleotides

Question 4

What are the multiple functions of RNA polymerase?

Answer 4

Searches DNA for transcription start sites -promoters

Unwinds short amounts of DNA and selects correct ribonucleoside triphosphates

Then detects termination signals- transcription ends

Question 5

Prokaryotic RNA polymerase has two forms, what are they?

Answer 5

1.Core enzyme- contains alpha alpha beta beta prime

2.holoenzyme enzyme-core enzyme and sigma factor

Question 6

What do Promoter and Terminator sequences do?

Answer 6

Promoter-Directs RNA pol to transcription start site
Terminator-stops RNA pol from transcription and releases RNA chain

Question 7

What two numbers indicate to the RNA pol in prokaryotes that there are promoter sequences?

Answer 7

-35 and -10

Question 8

What does the sigma subunit (part of holoenzyme) bind to?

Answer 8

Binds to promoter sequences at -10 and -35

Question 9

What does RNA pol unwind?

Answer 9

RNA pol unwinds DNA exposing template DNA strand (Doesn’t require energy)

Question 10

What does RNA pol unwind?

Answer 10

RNA pol unwinds DNA exposing template DNA strand (Doesn’t require energy)

Question 11

What’s the difference between Core enzyme and Holoenzyme of RNA polymerase?

Answer 11

Holoenzyme is basically a core enzyme with a sigma factor

Question 12

What does the sigma subunit do and after how many nucleotides does it leave?

Answer 12

Helps RNA polymerase recognise promoter of gene

Approx ten nucleotides (core enzyme continues to transcribe DNA)

Question 13

What are the two types of termination signals?

Answer 13

1.Rho dependant
2.Rho independent

Question 14

RNA pol in eukaryotes can’t find promoter sequence on their own, how do they find them?

Answer 14

Using other proteins

Question 15

What needs to happen to RNA to produce a mature RNA in eukaryotes

Answer 15

5’ capping adding GTP

Then spliced up for translation and taken out of the nucleus

Then 4A added (150 adenine) after splicing
Polyadenylation

Question 16

What is splicing in pre mRNAs

Answer 16

Removal of introns (non coding regions) then mature mRNA exported from nucleus