TEST 4 Translation

Question 1

What is IF1

Answer 1

Initiation Factor 1

Prevents premature binding of tRNAs to A site

Question 2

What is IF2?

Answer 2

Initiation Factor 2

Facilitates binding of fMet-tRNA to 30S ribosomal subunit.

Question 3

What is IF3

Answer 3

Initiation Factor 3

• Binds to 30S subunit;
• Prevents premature association of 50S subunit;
• Enhances specificity of P site for fMet-rRNA

Question 4

What is the Start Codon?

Answer 4

AUG - Methionine

Question 5

What is EF-Tu?

Answer 5

• When bound to GTP
  
  • It brings the secon amino acid into the A site of the ribosomal complex.
  • Then GTP —> GDP

Question 6

What does Diphtheria toxin do?

Answer 6

Catalyzes ADP-ribosylation of eEF2

Question 7

What does Ricin do?

Answer 7

Inactivates 60S subunit of eukaryotic ribosomes

Question 8

What does Puromycin do?

Answer 8

• Structure similar to 3’ end of aminoacyl-tRNA
  
  • Binds to A site
  • Participates in peptide bond formation
  • Cannot translocate or dissociate from the ribosome.

Question 9

What does Tetracycline do?

Answer 9

Blocks A site on ribosome in bacteria.

Question 10

What does Chloramphenicol do?

Answer 10

Blocks peptidyl transfer in bacteria

Question 11

What does streptomycin do?

Answer 11

Causes a misreading of genetic code in bacteria.

Question 12

What does Cycloheximide do?

Answer 12

Blocks peptidyl transferase in eukaryotic ribosomes.

Question 13

What causes Tuberous sclerosis complex?

Answer 13

• Associated with a defect in mTOR
  
  • Specifically TSC1/TSC2
  • Effects skin, brain, eyes, heart.
    
    • Abnormal growth of heart muscle.

Question 14

AUG codes for what?

Answer 14

START codon

Codes for methionine

Question 15

What does UAA code for and what recognizes it?

Answer 15

Stop codon

Question 16

What are the stop codons?

Answer 16

UAA, UAG, UGA

Question 17

Steps to build Initiation complex

Answer 17

• 30S subunit binds IF1 and IF3, then the mRNA
• IF2-GTP binds the 30S subunit and recruits fMet-tRNA, which base pairs with the start codon.
• The 50S subunit associates, IF2 hydrolyzes GTP.
  
  • IF 1,2,3 dissociate
• The 70S initiation ocmplex is formed.

Question 18

EF-Ts

Answer 18

Replace GDP with GTP in the Tu

Question 19

EF-G

Answer 19

Binds to A site causing tRNA at A site to move to P site, and the tRNA at the P site to move to the E site.