Transcription And Rna Processing

Question 1

RNA pol in prokaryotes

Answer 1

only one type for all type of RNAs

Question 2

role of sigma and rho factors in prokaryotic RNA pol

Answer 2

sigma: for initiation of transcription
rho: for termination

Question 3

types of RNA pol in eukaryotes

Answer 3

3 types
I: in nucleolus- rRNA(28,18,5.8S ) except 5sRNA

II: in nucleoplasm-mRNA/hnRNA ,some snRNA

III:in nucleoplasm-some snRNA, tRNA, 5sRNA

I -rRNA
II -mRNA
III -tRNA

Question 4

RNA is synthesised from

Answer 4

5’ to 3’ direction just like DNA

Question 5

does RNA pol has proofreading activity

Answer 5

no

but DNA pol has

Question 6

which strand of the dna has the same sequence as RNA

Answer 6

coding/antitemplate strand

Question 7

direction of translation with respect to protein synthesis

Answer 7

from amino to carboxyl side

Question 8

the bacterial promoter contains which 2 consensus sequences

Answer 8

• 10/TATA/prinbow box

- 35 sequence

Question 9

which are the two types of transcription terminators found in prokaryotes

Answer 9

1. rho independent:newly formed rna folds back on itself to form GC rich hairpin loop followed by U residues
2. rho depenedent on binding to RNAP

termination is not well understood in eukar

Question 10

what is shine dalgarno sequence

Answer 10

ribosomes bind to this sequence in the 5’ untranslated region of mRNA for translation

found in prokaryotes

Question 11

polycistronic mRNA

Answer 11

mRNA contains information from several genes of DNA and codes for different proteins

only in prokaryotes

Question 12

in prokaryotes trancription and translation occur at the same time in cytoplasm.t/f

Answer 12

yes

no nucleus + no processing of mRNA is required

Question 13

promoter region in the eukaryotes has which 2 consensus sequence

Answer 13

TATA/hogness box

CAAT

Question 14

what are the post transcriptional changes occuring in eukaryotic hnRNA

Answer 14

CAPPING–addition of methyl guanosine (ribosome binding site and prevent degradation)

TAILING– addition of poly A tail (prevents degradtion and helps transport)

SPLICING–removal of exons by spliceosomes (snRNA + proteins)

Question 15

28S RNA (eukaryotic ribosome) is the target of which bacterial toxin

Answer 15

shiga toxin(shigella dysentrae)

shiga like toxin(enterohaemorraghic E.coli)

so inhibit protein synthesis

Question 16

a.a. attach at which site of tRNA

Answer 16

3’ / OH end

Question 17

RNA editing?

Answer 17

a process by which some cells make discrete changes to nucleotide sequence within a RNA molecule after its gene has been trancribed by RNAP

Question 18

eg of RNA editing

Answer 18

cytosine deamination to form uracil

apoprotein B100(liver) and B48(intestine) by C to U which forms a dtop codon.