Lecture 3

Question 1

Translation is also important in human health for reasons including:
Bacterial translation is a target of –

Answer 1

common antibiotics,

Question 2

Translation is also important in human health for reasons including: Viruses like influenza – for viral reproduction

Answer 2

co-opt translation

Question 3

Translation is also important in human health for reasons including: Translational control in – may be especially important for learning and memory

Answer 3

neurons

Question 4

Soon after the transcript is initiated the 5’ end is

modified by addition of a guanosine nucleotide in an unusual –

Answer 4

5’ to 5’ phospotriester bond.

Question 5

The guanosine is – on the N7 position after addition and the 2’ OH positions of the first two bases of the original transcript can also be methylated.

Answer 5

methylated

Question 6

The cap
protects the 5’ end from degradation by
– and it is involved in mRNA binding to the ribosome

Answer 6

exonucleases

Question 7

mRNAs have – of about 200 As at their 3’ end

Answer 7

poly A tails

Question 8

Transcriptional termination depends on –

Answer 8

poly A addition

Question 9

Normally, the polymerase terminates transcription 500-2000 bases beyond the site of poly A addition. Thus, the RNA must be – before the As are added.

Answer 9

cleaved

Question 10

A multiprotein complex recognizes AAUAAA and cleaves the RNA 20-50 bases –.

Answer 10

downstream

Question 11

after cleavage, poly A polymerase adds about 200 As in a –

Answer 11

non-templated reaction

Question 12

poly A tails are thought to protect the 3’ end from degradation by –

Answer 12

exonucleases.

Question 13

Most eukaryotic genes contain regions that are included in the mature mRNA (–) and regions that are excised from the initial transcript (introns).

Answer 13

exons

Question 14

Introns are removed from the initial RNA transcript by –

Answer 14

splicing

Question 15

Splicing must be precise because if the junction is off by even one base then the –will be altered, resulting in a mutation.

Answer 15

reading frame

Question 16

At the 5’ exon/intron boundary is the sequence AG/GU – this is known as the – or 5’ splice site.

Answer 16

splice donor site

Question 17

At the 3’ intron/exon boundary is the sequence AG/G – this is known as the – or 3’ splice site.

Answer 17

splice acceptor site

Question 18

Near the 3’ end of the intron is a sequence containing mostly pyrimidine nucleotides (pyrimidine-rich) and a nearby critical adenine nucleotide (called the –).

Answer 18

branch point

Question 19

Splicing is carried out by a large complex called the –

Answer 19

spliceosome

Question 20

Spliceosomes are made up of – that each contain a snRNA and 6-10 proteins.

Answer 20

small nuclear ribonucleoprotein particles (snRNPs)

Question 21

Since the RNAs have many U nucleotides, the snRNPs are referred to as –

Answer 21

U1-U6.

Question 22

– binds the 5’ splice site GU

Answer 22

U1

Question 23

U2AF binds 3’ splice site AG and the pyrimidine-rich sequence, SF1 binds branchpoint A. – displaces SF1

Answer 23

U2

Question 24

Then U4,5,6 bind to form a – putting the A near the 5’ exon/intron boundary

Answer 24

looped structure

Question 25

The A forms a – with the first G of the intron, cleaving the exon-intron phosphodiester bond, and forming a looped RNA called a lariat.

Answer 25

2’ to 5’ phosphodiester bond (first transesterification)

Question 26

Then the free 3’ end of the first exon is joined to the–releasing the lariat intron.

Answer 26

5’ end of the next exon, (second transesterification)

Question 27

different proteins can be generated from –by “alternative” splicing

Answer 27

one gene

Question 28

That is, joining different combinations of exons can produce different mRNAs encoding different proteins.

Answer 28

alternate splicing

Question 29

The sequence of the human genome revealed that there are only about 25,000 genes but about 85,000 different mRNAs, suggesting that alternative splicing plays a key role in generating –in humans

Answer 29

protein diversity

Question 30

Mutations in RNA splice sites can cause–

Answer 30

inherited disease.

Question 31

Mutations can eliminate splice donor or acceptor sites, or –.

Answer 31

generate new sites

Question 32

Abnormal splicing then generates a –

Answer 32

defective protein.

Question 33

≈15% of single base-pair mutations that cause human disease result in mRNA splicing defects. Recent studies suggest that genetic changes that affect to splicing efficiency are a major contributor to –

Answer 33

complex traits.

Question 34

Almost all RNA processing occurs in the –

Answer 34

nucleus

Question 35

RNA is then transported from the nucleus to the –for translation.

Answer 35

cytoplasm

Question 36

RNA is transported to the cytoplasm as a complex with proteins (–)

Answer 36

ribonucleoprotein or RNP

Question 37

RNPs are actively transported through large channels in the nuclear envelope –

Answer 37

nuclear pores