Protein Translation

Question 1

A ribosome consists of:

Answer 1

Large = 50S in bacteria and 60S in eukaryotes with 36 proteins

Small subunit: 30S in bacteria 40S in eukaryotes with 21 proteins

Question 2

The sequence of ribosome assembly:

Answer 2

Small subunit -> add mRNA (in eukaryotes the mRNA is placed on the 40S unit through 5´cap, poly-A tail, and proteins),
tRNA charged with Met, and GTP for energy -> add 60S unit

Question 3

The sequence of Elongation:

Answer 3

charged tRNA binds to A site -> Formation of a peptide bond between new aa and growing chain -> movement of growing chain to the P site

Energy from GTP hydrolysis

Question 4

What is the formation of multiple ribosomes on an mRNA transcript called?

Answer 4

Polysome

Question 5

The action of Streptomycin and site of action:

Answer 5

Inhibit initiation and causes misreading (prokaryotes) on 30S subunit
Class: Aminoglycosides

Question 6

The action of Tetracycline and site of action:

Answer 6

Inhibits binding of aminoacyl-tRNAs on 30S subunit (prokaryotes)
Class: Tetracyclines (4 rings)

Question 7

The action of Chloramphenicol/Cycloheximide and site of action:

Answer 7

Chloramphenicol: Inhibits the peptidyl transferase activity of the 50S subunit in prokaryotes

Cycloheximide in the 60S subunit of eukaryotes

Question 8

The action of Erythromycin and site of action:

Answer 8

Binds the 50S subunit and inhibits translocation

Class: macROlides

Question 9

The action of Puromycin and site of action:

Answer 9

causes chain termination by acting as an analog of amino-acyl tRNA on pro- and eukaryotes