exam 2 (RNA processing)

Question 1

how do eukaryotes and prokaryotes differ in translation

Answer 1

prokaryotes are translated as its transcribed

eukaryotes aren’t ready to be translated right after being transcribed, and have spacial separation

Question 2

for eukaryotes, where does transcription and translation occur

Answer 2

transcription = nucleus 
translation = cytoplasm

Question 3

for prokaryotes, where does transcription and translation occur

Answer 3

together in the cell

Question 4

how does newly synthesized RNA and mature mRNA differ in size

Answer 4

newly synthesized RNA is ~10x longer

Question 5

what is pre-mRNA

Answer 5

hnRNA, newly synthesized RNA

Question 6

mRNA and hnRNA are digested by what

Answer 6

ribonucleases

Question 7

in an RNA sequence, T, RNase digests what

Answer 7

G’s

Question 8

in a RNA sequence, Pancreatic RNase digests what

Answer 8

U’s and C’s

Question 9

mRNA and hnRNA have ends with a lot of A’s. why?

Answer 9

they are 3’ poly(A) tails

found in most eukaryotes

Question 10

what are the exception to all eukaryotic mRNAs having poly(A) tails

Answer 10

histone genes

Question 11

how do humans and yeast compare in their formed poly(A) tails

Answer 11

humans are a lot longer than yeast

Question 12

how are mRNA’s capped at their 5’ end

Answer 12

7-methylguanosine cap is put on to prevent it from growing (5’-m7G)
must be 20-30 nt long
phosphoryation of the RNAPII CTD

Question 13

what is the function of the 5’-m7G cap

Answer 13

-protect mRNA from digestion by 5’ –> 3’ exonucleases
-influence RNA export and processing
-translation
-

Question 14

how is hnRNA converted to mRNA

Answer 14

by removing internal parts of hnRNA sequences

Question 15

how were split genes discovered

Answer 15

studied viral DNA from infected human cells. There was formed hybrids between viral DNA and late mRNA

Question 16

exon

Answer 16

transcribed region that encodes amino acids

Question 17

intron

Answer 17

transcribed sequence between exons that doesn’t encode amino acids

Question 18

what is splicing and how often does it occur

Answer 18

allows cells to pick the exons they want to use for their mature mRNA
>95%

Question 19

what is exon skipping

Answer 19

skipping the cassette exon that is in between 2 constitutive exons

Question 20

what is mutually exclusive exons

Answer 20

one of the 2 middle exons are skipped

Question 21

what is intron retention

Answer 21

when introns that are normally spliced out remain in sequence

Question 22

alternative splicing

Answer 22

alternative spicing sites allow different pieces of the same exon to be included or excluded

Question 23

how are lariat structures formed during splicing

Answer 23

-OH substituents make attacks on on exons, joining exons 1 and 2 together

Question 24

when does splicing occur

Answer 24

when mRNA is transcribed

Question 25

CPSF function

Answer 25

binds poly(A) signal and is required for cleavage and polyadenylation

Question 26

poly(A) polymerase function

Answer 26

Adds as to the 3’ end of the mRNA and is also required for cleavage

Question 27

RNAPII CTD function

Answer 27

binds to CPSF and is required for cleavage

Question 28

what is RNA editing

Answer 28

allows a cell to recode genetic information, prior to translation of a mRNA, certain nucleotides can be changed

Question 29

what letter nucleotide associates with inosine in mRNA and tRNA

Answer 29

A

Question 30

roles of polyadenylation

Answer 30

transcription termination \

export of mRNA from nucleus to cytoplasm