Transcription in eukaryotes

Question 1

What are the four reasons transcription in eukaryotes is more complex than prokaryotes? IE what are the differences in transcription in prokaryotes versus eukaryotes?

Answer 1

Eukaryotes have more genes that are spaced further apart
Eukaryotes have three RNA polymerases (RNA 1, RNA2, RNA3)
Transcription takes place in the nucleus
DNA in eukaryotes is packed into chromatin

Question 2

What are general transcription factors in eukaryotes?

Answer 2

these bind sequences in the promoter

Question 3

What are promoter elements?

Answer 3

specific sequences in the promoter

Question 4

What happens after the general transcription factors bind to the different sequences in the promoter?

Answer 4

The RNA polymerase two, binds to the promoter at the +1 site.

Question 5

What happens to the RNA polymerase as it binds to the +1 site on the promoter?

Answer 5

It causes phosphorylation of the C terminal domain, done by transcription factor TF11H

Question 6

What is the pre initiation complex?

Answer 6

The complex of RNA polymerase 11 and general transcription factors

Question 7

Why is the CTD of RNA polymerase 11 phosphorylated?

Answer 7

to facilitate the processing of the 5’ mRNA which is capping of m7G

Question 8

Where is m7g cap and why is it there and what does it do?

Answer 8

is the addition of a methylated guanine nucleotide on the 5’ end of the mrna which protects the mRNA from decay by exonucleases, it also assists in splicing and and translation

Question 9

What is the poly a signal?

Answer 9

Is when sequences in the 3’ UTR that signal for rna polymerase to to leave rna pol 2 and then signal for additon of poly a tail bi different enzymes

Question 10

What is the poly A tail?

Answer 10

Is 50-250 A’s added on the 3’ end of mrna

Question 11

When does the poly A tail get added?

Answer 11

After transcription ends

Question 12

What does the poly A tail do?

Answer 12

Protects from 3’ end from decay and aid sin translation

Question 13

How does splicing produce different mrna that encode for different proteins from the same mRNA?

Answer 13

it can be spliced in diff ways near the junctions of exons and introns

Question 14

What is the kozaq sequence in mature eukaryotic DNA?

Answer 14

the 5’ UTR, is a landing site for ribosomes

Question 15

What are the diff parts of mature eukaryotic mRNA?

Answer 15

M7G cap
+1 site
5’ UTR
Start codon
coding region
3’ Utr
poly a signal
poly a tail

Question 16

What type of regulatory protein factor binds directly to the DNA?

Answer 16

Transcription factors

Question 17

What type of regulatory protein factor DOES NOT bind directly to the DNA?

Answer 17

Coregulators

Question 18

What things do coregulators bind to?

Answer 18

Other proteins

Question 19

Are transcription factors repressors or activators?

Answer 19

Can be both

Question 20

Are coregulators repressors or activators?

Answer 20

can be both, coactivator or corepressor

Question 21

Transcription factors can bind to what in the DNA?

Answer 21

Enhancers or promoters

Question 22

What are enhancers?

Answer 22

hundred to thousands of base pairs upstream or downstream of the transcription start site

Question 23

What are promoters? What kinds are there?

Answer 23

The promoter is usually where RNA polymerase sits to initiate transcription, the two types are proximal and core

Question 24

Where is the core promoter located? What about the proximal promoter?

Answer 24

The core promoter is located near the +1 site, the proximal promoter is before that

Question 25

Why do transcription factors bind to the proximal promoter?

Answer 25

To promote transcription

Question 26

What binds to the core promoter?

Answer 26

General transcription factors

Question 27

What binds to the general transcription factors:

Answer 27

RNA polymerase

Question 28

How do coregulators mediate long-range interactions?

Answer 28

As the DNA loops, the enhancer becomes close to the +1 site, allows interactions with transcription factors and rna polymerase

Question 29

What is TFIID (coregulator or transcription factor?)

Answer 29

Can act as both, can bind to core promoter and bind to RNA polymerase

Question 30

What are the four domains of transcription factors?

Answer 30

DNA-binding domain
Dimerization domain
Ligan-binding domain
Activation/repression domain

Question 31

What is the dimerization domain?

Answer 31

Can facilitate formation of dimers (homo or hetero) to create complex transcription factors

Question 32

What is the ligand binding domain?

Answer 32

hormones and vitamin bind shere which effects how the transcription factor interacts with dna

Question 33

What domains do you need in transcription factors?

Answer 33

the DNA binding domain and the activation/repression domain