Protein Synthesis

Question 1

A Site

Answer 1

Entry site for charged aminoacyl tRNA bound to ATP

Question 2

P Site

Answer 2

Occupied by peptidyl tRNA carrying growing polypeptide chain, where peptidyl transferase forms new peptide bonds between amino acids

Question 3

E Site

Answer 3

tRNA exits after delivering amino acid

Question 4

Inosine

Answer 4

Deaminated adenine via posttranscriptional modification, can base pair with A, U and C –> same tRNA can recognize 3/4 alanine codons bc of this wobble position, don’t need three.

Question 5

EF2

Answer 5

Elongation factor used for ribosome translocation; target of pseudomonas aerguniosa exotoxin A

Question 6

Pseudomonas exotoxin A

Answer 6

ADP-ribose that targets diphthamide post translational modification of histidine at position 715 of EF2. Stops protein synthesis of the host so it can kill cell and lyase for nutrients.

Question 7

Globin Synthesis Regulation

Answer 7

EIF2 is inactive when phosphorylated and active when unphosphorylated. Regulated by HRI and PPase 1.

Heme negatively regulated HRI – when heme levels are high, HRI is inhibited and EIF2 is unphosphorylated. Exchanges GDP for GTP nd initiates translation of globin.

When heme levels are low, HRI is active and EIF2 is phosphorylated (inactive).

Question 8

Ferritin Expression

Answer 8

IRP binds RNA element in 5’ UTR of ferritin gene when iron is low to inhibit translation of ferritin. When iron is high, repressor is inhibited allowing ferritin expression for iron storage.