Translation

Question 1

What is translation?

Answer 1

making the protein coded for by the mRNA strand, at the ribosome

Question 2

Which organelles are involved in translation?

Answer 2

ribosomes

Question 3

What is the role of tRNA in translation?

Answer 3

• tRNA has an amino acid binding site at one end and an anti-codon
• tRNA binds to an amino acid and attaches itself to mRNA by complementary base pairing
• two molecules attach to mRNA at a time
• the amino acids at the other end of tRNA join by a peptide bond

Question 4

Why might a polypeptide chain consist of one less amino acid than there are codons?

Answer 4

As one codon is a stop codon, which does not code for an amino acid

Question 5

Describe how one amino acid is added to a polypeptide that is being
formed at a ribosome during translation

Answer 5

• tRNA brings specific amino acid (to ribosome)
• Anticodon (on tRNA) binds to codon (on mRNA)
• Amino acids join by condensation reaction (using ATP)
  (peptide bond)

Question 6

Describe how a polypeptide is formed by translation of mRNA (7 marking points)

Answer 6

• (mRNA attaches) to ribosomes
• (tRNA) anticodons (bind to) complementary (mRNA) codons
• tRNA brings a specific amino acid
• Amino acids join by peptide bonds
• (Amino acids join together) with the use of ATP
• tRNA released (after amino acid joined to polypeptide)
• The ribosome moves along the mRNA to form the polypeptide