Question

Study the schematic diagram given below and answer the questions that follow:

1. Identify the polarity from 'X' to '`bar(X)`' in the mRNA segment shown. Mention how many more amino acids can be added to the polypeptide that is being translated and why.        [1.5]
2. Write the initiating codon for translation, its anticodon and the amino acid it codes for.        [1.5]
3. Explain the charging of an adaptor molecule. Why this molecule needs to be charged?         [1]

Answer 1

1. Polarity is from 5′ to 3′. The UAA stop codon prevents the addition of any additional amino acids.
2. The initial codon for translation is AUG. The transfer RNA (tRNA) molecule's complementary anticodon is UAC. AUG codes for the amino acid methionine (Met).
3. Charging an adaptor molecule, which is a tRNA molecule, entails attaching the relevant amino acid to its corresponding tRNA molecule. This process is facilitated by an enzyme known as aminoacyl-tRNA synthetase. The charging of tRNA molecules is required for correct and efficient protein synthesis during translation. Without charge, tRNA molecules are unable to transfer the necessary amino acids to the ribosome, resulting in mistakes in polypeptide chain production. Charging ensures that each tRNA molecule is accurately paired to its corresponding amino acid, ensuring protein synthesis accuracy.