Translation

Question 1

Transfer RNA (tRNA)

Answer 1

Folded into 3-lobed shape, with one having anticodon, and opposite one contains amino acid attachment site
- When amino acid is bound = amino-acyl tRNA (aatRNA)

Question 2

Ribosomes

Answer 2

Bring together mRNA and tRNA –> made up of protein + rRNA with two subunits, one small and one large, and 3 binding sites
- E site: releases tRNA
- P site: holds aatRNA and growing chain of amino acids
- A site: holds tRNA bringing next amino acid

Question 3

Initiation

Answer 3

mRNA reaches cytoplasm and rRNA binds to 5’ end of mRNA at start codon “AUG” –> initiator tRNA with anticodon “UAC” binds to ribosomal-mRNA complex, carrying a.a. methionine

Question 4

Elongation

Answer 4

mRNA codon in A site forms base pair with incoming aatRNA and peptide bond forms connecting chain of amino acids in P site to amino acid in A site

Question 5

Elongation: Translocation

Answer 5

Ribosome moves distance of 3 nucleotides in 5’–>3’ direction, causes new A site to be exposed, aatRNA with growing chain of amino acids moves to P site, and old tRNA moves into E site

Question 6

Termination

Answer 6

Elongation stops when stop codon reached in A site –> release factor (protein) binds to A site and cuts off completed polypeptide from P site
- Polypeptide transported by chaperones to chaperonin where it gets folded