Lecture 13

Question 1

Early experiments indicated that RNA was synthesized as a longer –

Answer 1

precursor (pre- mRNA)

Question 2

Observation: The mRNA found associated with ribosomes was on average much – than pre-mRNA.

Answer 2

smaller

Question 3

T/F: Pre-RNA exist as free RNA molecules in the nuclei of eukaryotic cell

Answer 3

false

Question 4

RNA molecules are associated with an abundant set of nuclear proteins called –

Answer 4

heterogeneous ribonucleoprotein or hnRNP

Question 5

– : a term refering to pre-mRNA and other nuclear RNAs of various sizes.

Answer 5

heterogeneous nuclear RNAs (hnRNAs)

Question 6

Obvious difference: hnRNAs are – than cytoplasmic mRNAs (mature mRNA)

Answer 6

longer

Question 7

cytoplasmic mRNA is derived from hnRNA by

Answer 7

splicing

Question 8

The size difference between hnRNA and mature mRNA is primarily due to removal of –.

Answer 8

non-coding sequences called introns

Question 9

Eukaryotic mRNAs have a 5’ cap formed by a –

Answer 9

5’-5’ triphosphate linkage of a 7-methylguanylate (GTP) residue

Question 10

5’ cap functions

Answer 10

transport out of the nucleus, initiation of translation, protect from exonucleases

Question 11

– coding sequence of a gene that contributes to the mature mRNA; is translated into protein

Answer 11

Exons:

Question 12

Introns: non-coding sequence of a gene that is transcribed but is not part of the mature mRNA; is not –

Answer 12

translated

Question 13

Specific sequences are required to remove introns during splicing, one of which is the

Answer 13

branching point

Question 14

RNA splicing is performed by

Answer 14

spliceosome

Question 15

Spliceosome: large assembly of –

Answer 15

snRNAs (small nuclear RNAs) and snRNPs (small nuclear ribonucleoproteins)

Question 16

A pre-mRNA of a gene can be spliced in –

Answer 16

different ways

Question 17

– of the spliceosome recognize of the 5’ splice junction, the branch-point site, and the 3’ splice junction through base-pairing.

Answer 17

snRNAs

Question 18

Introns are removed and formed a branded structure a –

Answer 18

lariat

Question 19

Poly(A) polymerase adds A residues to the –

Answer 19

3’ end

Question 20

-- can be added to make the
complete Poly(A) tail

Answer 20

200-250 Adenosine residues

Question 21

Poly(A) tail functions to protect the mRNA from – by 3’ –> 5’ exonuclease

Answer 21

premature degradation

Question 22

– bind to AAUAAA to signal poly A tail

Answer 22

CPSF

Question 23

– cbinds to GU-rich element to signal polyA tail

Answer 23

CstF