Which of the following group of codons are synonymus in nature?
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Synonymous codons almost always differ only at their third nucleotide position (the "wobble" position).
This provides a buffer against point mutations, as a mutation at the third position often does not change the resulting amino acid.
Step 1: Understanding the Concept:
The genetic code is described as degenerate (or redundant).
This means that multiple distinct codons can specify the same single amino acid.
Codons that code for the same amino acid are called synonymous codons. Step 2: Detailed Explanation:
Let us analyze the amino acids encoded by each pair of codons in the options:
- Option (A) GUU and GUC:
Both of these codons belong to the valine family.
GUU and GUC both specifically code for the amino acid Valine.
Because they code for the same amino acid, they are synonymous codons.
This variation typically occurs at the third position of the codon, illustrating the "wobble hypothesis".
- Option (B) UUU and CCU:
UUU codes for Phenylalanine, while CCU codes for Proline. (Not synonymous).
- Option (C) CAA and CCU:
CAA codes for Glutamine, while CCU codes for Proline. (Not synonymous).
- Option (D) AGC and AGG:
AGC codes for Serine, while AGG codes for Arginine. (Not synonymous).
Therefore, only the pair GUU and GUC are synonymous in nature. Step 3: Final Answer:
The synonymous codons are GUU and GUC.
