Translation

Question 1

Stages of translation

Answer 1

• initiation
  -elongation
  -termination

Question 2

The code is triplet

Answer 2

3 nucleotides grouped together encodes for a single aminoacide

Question 3

Overlapping code

Answer 3

A change in one of the base pairs in the DNA would be expected to affect three consecutive codons and therefore three consecutive AA in the corresponding polypeptide

Question 4

Non-overlapping

Answer 4

Each nucleotide is part of only one coden then only one AA replacement would be expected

Question 5

Degenerate

Answer 5

Several codons correspond to the same AA

Question 6

Specific

Answer 6

A single codon can encode only one AA an it is strictly defined which one

Question 7

Start codons

Answer 7

AUG

Question 8

Stop codons

Answer 8

-UAG
-UGA
-UAA

Question 9

Properties of genetic code

Answer 9

-triplet
-Non-overlapping
-degeneratr
-specific
-universal

Question 10

3 sites of ribosome for association with tRNA

Answer 10

-A(aminoacyl)
-P(peptidly)
-E(exit,
deacylated tRNA released )

Question 11

Which ribosome for initiation stage

Answer 11

80s ribosome

Question 12

At initiation stage of translation, what is bound to the P site?

Answer 12

Met-tRNAi

Question 13

Role of Anticodon of tRNA in contact with small subunit?

Answer 13

Decoding the information contained in the mRNA

Question 14

Role of AA carrying ends in contact with large ribosomal subunit?

Answer 14

Catalyze peptide bound formation

Question 15

Special tRNAi

Answer 15

Initiate protein synthesis

Question 16

Regular tRNAmet

Answer 16

Incorporate met only into a growing protein chain

Question 17

Reading frame

Answer 17

From a specific start codon to a stop codon

Question 18

Translation initiation step 1

Answer 18

Bringing the small ribosomal subunit to the initiation codon

Question 19

In bacterial mRNA, nucleotides before the initiation codon

Answer 19

Shine dalgarno

Question 20

Shine dalgarno sequence is complementary to what?

Answer 20

Sequence of nucleotides near 3’ end of the 16S ribosomal RNA of small ribosomal subunit

Question 21

Role of shine dalgarno sequence

Answer 21

Guarantees the recognition and correct localization of initiation codon inside the ribosome

Question 22

Where does bacterial IF attach?

Answer 22

30s subunit

Question 23

IF1

Answer 23

-stabilizes attachment of 30s subunit to mRNA
-prevents initiator AA-tRNA from entering the wrong site on the ribosome

Question 24

IF2

Answer 24

GTP binding protein required for attachment of first AA-tRNA

Question 25

IF3

Answer 25

-Prevent larger (50s) subunit from joining prematurely to the 30s subunit -facilitate entry of the appropriate initiator AA-tRNA

Question 26

Translation initiation step 2

Answer 26

Bringing the first AA-tRNA into the ribosome

Question 27

Translation initiation step 3

Answer 27

Assembling the complete initiation complex

Question 28

Initiation step 3

Answer 28

Once the initiator tRNA is bound to the Aug codon and the IF3 is displaced, large subunit (60s) joins the complex and the GTP bound to IF2 is hydrolyzed

Question 29

Eukaryotes, AUG codon is recognized by what?

Answer 29

Cap structure by action of eIF4E factor

Question 30

2 complexes that begins initiation in Eukaryotes

Answer 30

-43s complex -mRNA complex

Question 31

43s complex

Answer 31

40s subunit bound to several initiation factors and initiator tRNA

Question 32

mRNA complex

Answer 32

mRNA bound to a separate group initiation factors

Question 33

Translation elongation step 1

Answer 33

-AA-tRNA selection -entry of 2nd AA-tRNA into Vacant A site

Question 34

GTPasr required for Binding of 2nf AA-tRNA to the A site

Answer 34

In bacteria - EF-Tu -in Eukaryotes - eEF1A

Question 35

Translation elongation step 2

Answer 35

Peptide bond formation

Question 36

Translation elongation step 2 is catalyzed by what?

Answer 36

rRNA acting as a ribozyme (peptidyl transferase)

Question 37

Translation elongation step 3

Answer 37

Translocation

Question 38

Translocation movement

Answer 38

-di peptidyl-tRNA from A site to P site of the ribosome - deacylated tRNA from the P site to the E site

Question 39

GTP bound EFs for translocation

Answer 39

Bacteria -EF-G Eukaryotes -eEF2

Question 40

Translation elongation step 4

Answer 40

Releasing the deacylated tRNA

Question 41

RF1

Answer 41

Bacterial, recognizes UAA and UAG stop codons

Question 42

RF2

Answer 42

Bacterial, recognizes UAA and UGA stop codons

Question 43

eRF1

Answer 43

Eukaryotes, recognizes all three stop codons

Question 44

RF3 and eRF3

Answer 44

Release of RF/eRF from ribosomal A site

Question 45

eRF3 GTP bound

Answer 45

eRF1 to promote cleavage of peptidyl tRNA

Question 46

final steps in translation

Answer 46

-release of deacylated tRNA from the P site -dissociation of mRNA from ribosome -disassembly of ribosome into it's large nd small subunit

Question 47

Increase in rate of protein synthesis

Answer 47

-simultaneous translation -rapid recycling of ribosomal subunits