Role of RNA in Gene expression

Question 1

Eukaryotic mRNAs are?

Answer 1

Monocistronic(copy of a single gene)

Question 2

Prokaryotic mRNAs are?

Answer 2

Polycistronic(contain information about several proteins)

Question 3

3’ end

Answer 3

Poly A tail

Question 4

5’ end

Answer 4

Methylated guanosine cap

Question 5

5’ cap functions

Answer 5

-protects from enzymatic degradation
-transportation to cytoplasm
-recognized by protein factor for initiation of mRNA translation

Question 6

tRNAs

Answer 6

-decodes information from mRNA
-acts as a adaptor

Question 7

Cloverleaf

Answer 7

Secondary structure of tRNA

Question 8

5 parts from Cloverleaf structure

Answer 8

-D loop
-T loop
-Anticodon loop
-variable loop
-acceptor stem

Question 9

Sequence in acceptor stem

Answer 9

CCA

Question 10

When is the CCA added?

Answer 10

After transcription processes. During modification / processing

Question 11

tRNA charging

Answer 11

Making sure that tRNA molecule be attached to correct AA

Question 12

AA are linked to 3’ ends of correct tRNA by which enzyme?

Answer 12

Aminoacyl-tRNA synthetase

Question 13

Amino acid activation

Answer 13

Attachment of appropriate AA and ATP to a specific enzyme Aminoacyl-tRNA synthase

Question 14

tRNA charging

Answer 14

-Enzyme transfers it’s bound AA to 3’ of correct tRNA forming high energy Ester bond
-AMP is replaced by tRNA in this step resulting in AAtRNA

Question 15

Aminoacyl-tRNA

Answer 15

Charged tRNA

Question 16

Catalase activity

Answer 16

Removal of wrong AA from tRNA itself by AAtRNA synthase

Question 17

Function of rRNA of large subunit

Answer 17

Formation of peptide bonds

Question 18

How many different rRNA molecules in bacteria?

Answer 18

3

Question 19

How many different rRNA molecules in Eukaryotes?

Answer 19

4

Question 20

Prokaryotic small ribosomal subunit

Answer 20

16s

Question 21

Prokaryotic large ribosomal subunit

Answer 21

-23s
-5s

Question 22

Eukaryotic small ribosomal subunit

Answer 22

18s

Question 23

Eukaryotic large ribosomal subunit

Answer 23

-28s
-5s
-5.8s

Question 24

In prokaryotes, the entire assembled ribosome

Answer 24

70s

Question 25

In Eukaryotes, the entire assembled ribosome

Answer 25

80s

Question 26

Ribozymes

Answer 26

RNAs having catalytic role