protein synthesis : translation

Question 1

translation

Answer 1

is the process of turning instructions from mRNA, into chains of amino acids

Question 2

what way are the codons read in translation

Answer 2

5’-3’

Question 3

what does each codon specify

Answer 3

the amino acid to be placed at the corresponding position along a peptide

Question 4

how many codons for amino acids (aa)

Answer 4

61

Question 5

what are the termination codons

Answer 5

UAA
UAG
UGA

Question 6

transfer RNA

Answer 6

amino acid attachment site at the 3’ end
anticodon loop contains 3 bases which base-pair with a complimentary codon on mRNA

Question 7

what is the alignment of 2 RNAs

Answer 7

antiparallel

Question 8

what base of the codon in mRNA pairs with 3rd base of the anticodon

Answer 8

1st base

Question 9

what does aminoacyl-tRNA synthetase do?

Answer 9

join amino acids to their tRNAs

Question 10

how many different synthetases

Answer 10

20

Question 11

what is the structural role of rRNA

Answer 11

components of ribosomes

Question 12

what is the catalytic role of rRNA

Answer 12

catalyses the formation of the peptide bond

Question 13

what is the site of translation

Answer 13

ribosomes

Question 14

what are ribosomes composed of ?

Answer 14

RNA and ribosomal protein

Question 15

what are the tree binding sites for tRNA

Answer 15

P site
A site
E site

Question 16

P site

Answer 16

holds the tRNA that carries the growing polypeptide chain

Question 17

A site

Answer 17

holds the charged tRNA that carries the next amino acid to be added to the chain

Question 18

E site

Answer 18

is the exit site, where discharged tRNAs leave the ribosome

Question 19

what does the cleft that two subunits form do?

Answer 19

mRNA passes through as the ribosome moves along mRNA during translation

Question 20

how many sites on complete ribosome for codon-anticodon interactions?

Answer 20

2

Question 21

mRNA

Answer 21

5’ untranslated
coding sequence
3’ untranslated

Question 22

5’ untranslated

Answer 22

Shine-Dalgarno (SD) sequence or ribosome binding site (RBS) allows mRNA to bind with ribosome

Question 23

initiation in prokaryotes

Answer 23

mRNA binds to 30S subunit
initiation AUG codon positioned at P site
charged tRNA with the first amino acid, binds to the AUG codon in the P site
GTP is hydrolysed
initiation factors are released and 50S binds to 30S

Question 24

what does GTP being hydrolysed do?

Answer 24

causes a conformational change

Question 25

how many codons are exposed at the interface between 30S and 50S

Answer 25

2

Question 26

elongation in prokaryotes

Answer 26

three steps for every AA added

Question 27

first step of elongation

Answer 27

binding of next charged tRNA

Question 28

second step of elongation

Answer 28

peptide bond formation catalysed by 23S rRNA

Question 29

third step of elongation

Answer 29

translocation movement of the ribosome along the mRNA by 1 codon

Question 30

where does the growing polypeptide exit the ribosome

Answer 30

through a tunnel in the center of the 50S subunit

Question 31

termination in prokaryotes

Answer 31

stops when stop codon is reached release factor binds water molecule causes polypeptide release

Question 32

where does the release factor carry the water molecule to

Answer 32

the peptidyl transferase center

Question 33

how are mRNAs read in prokaryotic and eukaryotic cells ?

Answer 33

read simultaneously by numerous ribosomes

Question 34

when can a second ribosome assemble and begin translating mRNA

Answer 34

as soon as the first ribosome has cleared the initiation codon