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Molecular Basis of Inheritance — BIOLOGY STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 ScienceBIOLOGYMolecular Basis of Inheritance5 Marks
Question
There is only one possible sequence of amino acids when deduced from a given nucleotide. But multiple nucleotide sequences can be deduced from a single amino acid sequence. Explain this phenomenon.
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Answer

Some amino acids are coded by more than one codon (known as degeneracy of codon), hence on deducing a nucleotide sequence from an amino acid sequence, multiple nucleotide sequences will be obtained.
For example: isoleucine has three codons AUU, AUC and AUA. Hence a dipeptide Met-Ile can have any of the following nucleotide sequences:
  1. AUG - AUU
  2. AUG - AUC
  3. AUG - AUA
If we deduce amino acid sequences of the above nucleotide sequences, all the three will code for Met-Ile.

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