8.5 Polypeptide synthesis- translation

Question 1

What is the role of translation in polypeptide synthesis?

Answer 1

• the codons of mRNA are translated into a sequence of amino acids which make up a polypeptide
• Each tRNA has a specific anticodon which attaches to a specific amino acid

Question 2

Describe the process of translation.

Answer 2

1) A ribosome attaches to the starting codon at one end of the mRNA molecule
2) the tRNA molecule (carrying a specific amino acid) with complimentary anticodon sequence moves to the ribosome and pairs up with the mRNA codon.
3) a tRNA molecule, carrying a different amino acid, with a complimentary anticodon pairs with the next codon on the mRNA.
4) the ribosome moves along the mRNA bringing together two tRNA molecules at once, each pairing with the complimentary codons on the mRNA
5) the two amino acids on the tRNA are joined by a peptide bond using an enzyme and ATP which is hydrolysed to provide energy
6) the ribosome moves to the 3rd codon on the mRNA , linking the amino acids on the second and third tRNA molecules.
7) the first tRNA is released from its amino acid to collect another one.
8) the synthesis continues until the ribosome reaches the stop codon.

Question 3

Describe the assembling of a protein.

Answer 3

• polypeptide is folded, producing the secondary structure
• secondary structure is folded, producing the tertiary structure
• different polypeptide chains and non-protein groups are linked to form the quaternary structure.