Lecture 8 - eukaryotic

Question 1

What is core made out of?

Answer 1

8 histone molecules, 2 each of H2A, H2B, H3, H4

Dyad axis of symmetry

Linked by linker (~60bp)

Question 2

Outline DNA condensing

Answer 2

Nucleosome 1:6
Solenoid 1:40
Chromosome 1:7000

Question 3

What does acetylation do?

Answer 3

Acetylates lysine groups in the histone tail, removes positive charges

Opposite for deacetylation

Question 4

Function of TFIIH in initiation?

Answer 4

Helicase

Kinase activity

Question 5

Function of RNA Pol II

Answer 5

Leaves pre-initiation complex and begins RNA synthesis

plays a role in elongation

Question 6

Outline classes of RNA modifications

Answer 6

End modifications occur during synthesis of mRNA:
A cap attached at 5’ end
polyA tail attached to 3’ end

Splicing

Question 7

Polyadenylation factors

Answer 7

PolyA signal sequence: AAUAAA
CPSF: Cleavage and apolyadenylation
CstF: cleavage stimulation
PAP : poly A polymerase
PolABinding protein: assists PAP recruitment/function

Question 8

What is the function of 5’ cap and 3’ polyA?

Answer 8

Both contribute to stability of mRNA

5’ required for translation (initation factor 4, elF4)

Question 9

What are the 4 major types of introns?

Answer 9

Introns in pre-tRNA
Group I (fungal mito,plastid,pre-rRNA)
Group II (fungal mito and plastids)
Introns in pre-mRNA (splicosome mediated)

Question 10

What sequences do introns begin and end with?

Answer 10

5’GU….AG 3’