4. RNA Structure and Synthesis

Question 0

Is RNA single stranded or double stranded

Answer 0

Single

Question 1

Is this topic more important than DNA

Answer 1

Yes

Question 2

Why is RNA liable to NaOH

Answer 2

because of the presence of a OH group at position 2

Question 3

classes of RNA

Answer 3

rRNA, mRNA, tRNA 
small nuclear RNAs 
small nuclear ribonucleoproteins - snRNPs 
microRNAs - miRNAs 
small interfering RNAs

Question 4

composition of prokaryotic RNAs

Answer 4

50s + 30s =70s

Question 5

composition of eukaryotic RNAs

Answer 5

60s + 40s = 80s

Question 6

shape of tRNA

Answer 6

clover leaf shape

Question 7

what RNA carries genetic information from nuclear DNA to the cytosol

Answer 7

mRNA

Question 8

what constitutes RNA polymerase

Answer 8

sigma factor, 2 alphas, one beta and one beta prime

Question 9

function of the sigma factor

Answer 9

enables RNA polymerase to recognize and bind more tightly to promoter regions on the DNA

Question 10

characteristics of RNA polymerase (prokaryotic)

Answer 10

syntehesizes RNA in the 5’-3’ direction
Does not require a primer
has no exonuclease or endonuclease activity
no ability to repair mistakes

Question 11

3 parts of transcription

Answer 11

Initialtion, elongation. termination

Question 12

promoter regions

Answer 12

sequences in DNA that determine the start point and the frequency of transcription (located short distance upstream from where transcription starts

Question 13

consensus sequences

Answer 13

when the codon is not 100% like the pribnow

Question 14

pribnow

Answer 14

TATAAT

Question 15

what step of transcription does rifampicin act?

Answer 15

Initiation

Question 16

what occurs that causes the enzyme to enter elongation mode

Answer 16

release of sigma factor

Question 17

what enzyme is used in elongation

Answer 17

ribonucleotide triphosphates

Question 18

2 modes of termination

Answer 18

rho dependent and rho independent

Question 19

features of rho dependent

Answer 19

regularly spaced C residues that rho factor binds to

It is a hexameric protein

Question 20

features of rho independent termination

Answer 20

involves a consensus sequence (inverted repeats) followed by poly U
RNA polymerase pauses after it synthesizes that RNA

Question 21

how does Actinomycin D act

Answer 21

interfere with the movement of RNA polymerase along the DNA

Question 22

what does acetylation of histones do

Answer 22

leads to activation of gene expression

Question 23

what is the most significant effect of histone modification?

Answer 23

ability to attract specific proteins to a stretch of chromatin.

Question 24

Are histone modifications reversible?

Answer 24

Yes

Question 25

how are acetyl groups added to lysines

Answer 25

histone acetyl transferases

Question 26

how are acetyl groups removed from lysines

Answer 26

histone deacetylase complexes

Question 27

where does methylation of DNA occur

Answer 27

CG sequence

Question 28

what does methylation of eukaryotic DNA do

Answer 28

decreases transcriptional activity - by preventing the binding of transcription factors

Question 29

what is the function of chromatin remodeling

Answer 29

provides rapid access to many specific DNA sequences

Question 30

RNA polymerase

Answer 30

used in transcription of tRNA genes, must be initiated by general transcription factors TFIIIC and TFIIIB

Question 31

what facilitates the binding of RNA polymerase

Answer 31

transcription factors that bind to the TATA box

Question 32

What are enhancers?

Answer 32

regulatory cis-acting DNA sequences

Question 33

silencers

Answer 33

reduce the level of gene expression

Question 34

4 thngs that must be added to prokaryotes in post translational modification

Answer 34

5' capping RNA Splicing 3' poly adenylation RNA cap

Question 35

what is 5' capping

Answer 35

addition of 7 guanosine to 5' terminal end

Question 36

what enzyme catalyses methylation of guanine in cytosol

Answer 36

guanine-7-methyltransferease

Question 37

what are the splicing donors

Answer 37

GU at the 5' | an adenosine at the branch point

Question 38

what is the splice acceptor

Answer 38

AG at the 3'