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AIIMS2010ZoologyMolecular Basis of Inheritance

Which of the following is correct regarding genetic code?

Options

  1. AUUU is the initiation codon which also codes for phenylalanine.
  2. BThere are 64 triplet codons and only 20 amino acids.
  3. CThree random nitrogen bases specify the placement of one amino acid.
  4. DUAA is the nonsense codon which also codes for methionine.

Correct answer

B. There are 64 triplet codons and only 20 amino acids.

Step-by-step solution

There are 64-triplet codons that code for 20 amino acids. This is due to the degeneracy of code as some amino acids are influenced by more than one codon. Only tryptophan and methionine are specified by single codons. All other amino acids are specified by two (e.g., phenylalanine UUU , UUC ) to six (e.g., arginine-CGU, CGC, CGA, CGG, AGA, AGG) codons.

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