lecture 30

Question 1

The formation of Prokaryotic Translation Complex

Answer 1

• the GTP and the ignition factors bind to the small subunit
• the mRNA and a fMET-tRNA bind to the small subunit with the Shine-Dalgarno Sequence binding to the subunit’s 16 rRNA releasing IF3
• the GTP is hydrolyzed binding the large and small subunits after the initiation factors (1&2) leave and the 70S subunit is complete

Question 2

What is the Shine-Dalgaero Sequence

Answer 2

its a sequence with a mixture of purines 7-8 nucleotides upstream of the start codon to locate it an make it line up with the P site

Question 3

which way does the mRNA move

Answer 3

e to p to a

Question 4

Transitional elongation

Answer 4

1) the F2 brings the tRNA to the A site. The F2 hydrolyzes the GTP giving it the power to move from 5’ to 3’ for the next codon
2) the peptidyl transferase binds the amnio acid wth the previous one

Question 5

How does the peptide transferase bind the amino acids

Answer 5

• the amine of amino acid in the A site attacks the ester carbonyl in the P site
• that chain now is on the tRNA of the A site
• the mRNA will slide down so the tRNA in the P site will move to the E site allowing the one in the A site to move to the P site

Question 6

How does the tRNA leave?

Answer 6

since the E site is the only site mainly in th large subunit, the bond between the large and small unit is weaker allowing the tRNA to get out

Question 7

Transational Termination

Answer 7

Release factor 2 will bind to the stop codon and ending to GTP hydrolization and all components will be released

Question 8

How long does protein synthesis take?

Answer 8

20 seconds - several minutes

Question 9

Polyribosome

Answer 9

many synthesis occurring on one mRNA at the same time (usually a mRNA that is 80 nucleotides long)

Question 10

when do proteins start folding

Answer 10

protein will fold into secondary and tertiary structures after leaving the ribosome because that info is in the secondary structure.