Protein Synthesis

Question 1

UTR

Answer 1

Untranslated Region - sequence of mRNA between the 5’ cap and coding region and the Poly A tail and coding region, is not translated

Question 2

codon

Answer 2

trinucleotide sequence that coeds for specific amino acids

Question 3

cloverleaf folding

Answer 3

characteristic folding of tRNA molecules

Question 4

aminoacyl-tRNA synthetases

Answer 4

activates amino acid by adding AMP and then transfers to the terminal nucleotide of a specific tRNA

Question 5

aminoacyl-tRNA

Answer 5

a complex of a specific amino acid and tRNA molecule

Question 6

anticodon

Answer 6

trinucleotide sequence of tRNA that binds to mRNA by complementary base pairing

Question 7

Wobble hypothesis

Answer 7

the third codon has “relaxed” bonding, allows a single tRNA to recognize several codons

Question 8

eIF-2

Answer 8

eukaryotic initiation factor 2 - binds to Met-tRNA and GTP and recruits small 40S ribosomal subunit, once a start codon is found, GTP is used and eIF-2 is released

Question 9

eIF4F

Answer 9

recognizes and associates with 5’ cap of mRNA, orients 40S ribosomal subunit to mRNA

Question 10

P site (peptidyl site)

Answer 10

site of the growing amino acid chain on the mRNA

Question 11

A site (aminoacyl site)

Answer 11

site available for the attachment of the incoming aminoacyl-tRNA

Question 12

EF1

Answer 12

elongation factor 1, helps the aminoacyl-tRNA to bind to the A site on ribosomes, uses GTP

Question 13

peptidyl transferase

Answer 13

forms the peptide bond between amino acids of the growing peptide chain

Question 14

EF2

Answer 14

elongation factor 2, translocates the mRNA on the ribosome so the A site is now open and the tRNA can be released

Question 15

termination factor

Answer 15

binds to the A site and promotes the cleavage of polypeptide chain from tRNA once a stop codon is reached

Question 16

monocistronic mRNA

Answer 16

Only one protein is encoded for each mRNA transcript

Question 17

missense mutation

Answer 17

one base is changed and the improper amino acid may be added to the peptide chain

Question 18

nonsense mutation

Answer 18

a mutation that results in premature termination

Question 19

frame-shift mutation

Answer 19

a mutation that adds or subtracts a base and leads to completely different amino acids during translation

Question 20

phosphorylated eIF2

Answer 20

inactive, occurs in times of stress (lowers levels of translation)

Question 21

IRES

Answer 21

internal ribosome entry sites, recruits pre-initiation complex that does not involve initial scanning process, used by viruses