Translation

Question 1

how many codons are there?

Answer 1

4 to the power of 3 - 64

Question 2

sense and non sense codons

Answer 2

61 sense and 3 non sense

Question 3

stop codons

Answer 3

UGA, UAA, UAG

Question 4

selenocysteine

Answer 4

21st amino acid

Question 5

selenocysteine cysteine is present in active site of many enzymes such as:

Answer 5

thioredoxin reductase
glutathione peroxidase
deoidinase

Question 6

codon that can be sense and non sense

Answer 6

UGA

Question 7

characteristics of genetic code

Answer 7

1. specificity
2. degeneracy
3. universality
4. reading frame

Question 8

specificity

Answer 8

each codon only codes for 1 amino acid

Question 9

degeneracy

Answer 9

some amino acids have more than 1 codon that codes for them

Question 10

synonym codons

Answer 10

codons that code for same amino acids

Question 11

which amino acids have 6 codons?

Answer 11

arginine and serine

Question 12

which amino acids only have 1 codon?

Answer 12

methionine and tryptophan

Question 13

universality

Answer 13

genetic code is universal (same codon codes for same amino acid in all living organisms) EXCEPT 4 codons in mitochondrial RNA that differ form cytoplasmic RNA

Question 14

Reading Frame

Answer 14

only 1 reading frame will produce a functional protein

ribosome reads mRNA in 5’ to 3’ direction

Question 15

initiation codon

Answer 15

AUG which codes for methionine

Question 16

genetic code is

Answer 16

uninterrupted, unoverlappeed and unpunctuated

Question 17

wobble theory

Answer 17

the first and second base on mRNA and corresponding tRNA is close apposition so classic base pairing.
The third base on mRNA is far from third on tRNA so tRNA recognize more than 1 codon for same amino acid.

So, only first 2 are essential and the third nucleotide is flexible.

Question 18

third base in a codon is

Answer 18

flexible

Question 19

anticodon 1st position on TRNA

U
G
I

Answer 19

codon position 3rd on mRNA

U- A or G
G- U or C
I - A or U or C

Question 20

requirements for protein synthesis (translation)

Answer 20

1. rRNA and ribosomes which contain enzyme peptide transferase
2. amino acids
3. mRNA
4. tRNA
5. Amino acyl tRNA synthetase
6. source of energy
7. protein factors

Question 21

protein factors

Answer 21

initiation, elongation and releasing factors

Question 22

source of energy in translation

Answer 22

ATP and GTP

Question 23

site of protein synthesis in eukaryotes vs prokaryotes

Answer 23

Rough endoplasmic reticulum in eukaryotes

Cytosol in prokaryotes

Question 24

activation of amino acids

Answer 24

amino acids turns into enzyme amino acid AMP Complex with the help of amino acyl tRNA synthetase.

Enzyme amino acid amp complex turns into amino acyl + RNA + Enzyme

Question 25

amino acid is esterified on …

Answer 25

3’ OH of tRNA

Question 26

initiation requires

Answer 26

4 IFs (1, 2, 3, 4 ) 4 is most imp.

Question 27

the 40S subunit binds to

Answer 27

5’ cap of mRNA with help of IF-4 (cap binding protein)

Question 28

what scans the mRNA for initiation codon and what happens?

Answer 28

40S subunit, the tRNA binds and the 60S subunit binds to 40S to form the initiation complex

Question 29

sites of 80S ribosome

Answer 29

Amino Acyl (A) site
Peptidyl (P) site
Exit (E) site

Question 30

at end of initiation, P site and A site:

Answer 30

P site: occupied by met-tRNA

A site- Free and ready to accept next amino acyl

Question 31

elongation steps

Answer 31

multi cyclic process and envolves;

1. Binding of new aminoacyl tRNA
2. peptide bond formation
3. translocation of ribosome

Question 32

binding of new amino acyl tRNA to A site requires

Answer 32

EF-1 and GTP

Question 33

GTP is hydrolyzed by

Answer 33

GDP + Pi

Question 34

60S ribosome contains enzyme…

Answer 34

peptidyl transferase

Question 35

polysomes (polyribosomes)

Answer 35

many ribosomes can translate same mRNA at same time but must be 80-100 nucleotides apart