Lecture 08

Question 1

Codon

Answer 1

Group of 3 consecutive nucleotides in RNA

Question 2

Structure of tRNA

Answer 2

Cloverleaf with 2 regions of unpaired nucleotides

1. Anticodon loop: 3 consecutive nucleotides that pair with complementary codon in mRNA molecule
2. 3’CCA terminal region: binds amino acid that matches corresponding codon

Question 3

What are the 2 adaptors that assist in translation?

Answer 3

1. tRNA

2. aminoacyl-tRNA synthetase

Question 4

Small subunit of ribosomes

Answer 4

Framework on which tRNAs accurately matched to codons of mRNA

Question 5

Large subunit of ribosomes

Answer 5

Catalyzes formation of peptide bonds that link amino acids together into a polypeptide chain

Question 6

What are the 4 binding sites for RNA contained in the ribosome?

Answer 6

A, P, E and mRNA sites

Question 7

What binding sites are formed by rRNA on the large subunit of the ribosome?

Answer 7

A, P, and E sites

Question 8

In which direction are proteins synthesized?

Answer 8

From N to C terminal end

Question 9

What begins translation?

Answer 9

Initiation codon - AUG - codes for methionine

Question 10

Stop codons

Answer 10

UAA, UAG, UGA

Question 11

What is the mechanism behind antibiotics as inhibitors of protein synthesis?

Answer 11

Antibiotics bind to ribosomes, interfere with protein synthesis by blocking function

Question 12

Tetracycline

Answer 12

Blocks binding of aminoacyl-tRNA to A site of ribosome

Question 13

Streptomycin

Answer 13

Prevents transition from translation initiation to chain elongation and also causes miscoding

Question 14

Erythromycin

Answer 14

Binds in exit channel of ribosome and inhibits elongation of peptide chain

Question 15

Puromycin

Answer 15

Causes premature release of nascent polypeptide chains by addition to growing chain end

Question 16

Cycloheximide

Answer 16

Blocks translocation reaction on ribosomes