Which describes codon degeneracy?

Which describes codon degeneracy?

• A. Each codon codes for a unique amino acid
• B. A codon can code for multiple amino acids
• C. Multiple codons can code for the same amino acid
• D. Codons overlap between adjacent amino acids

Answer: (C)

Codon degeneracy means multiple codons can specify the same amino acid. There are 64 possible codons but only about 20 amino acids (plus stop signals), so the genetic code is redundant. This means many amino acids are encoded by more than one codon—for example, glycine can be specified by GGU, GGC, GGA, GGG; leucine and serine likewise have several codons. Often, these codons differ in the third base, the wobble position, so changes there may not alter the amino acid and the protein remains the same. This concept explains why a single amino acid can arise from different codons, and why mutations in the third base sometimes have no effect on the protein. It also reflects that codons are read in a fixed, non-overlapping reading frame, so no codon overlaps with the next one.

Codon degeneracy means multiple codons can specify the same amino acid. There are 64 possible codons but only about 20 amino acids (plus stop signals), so the genetic code is redundant. This means many amino acids are encoded by more than one codon—for example, glycine can be specified by GGU, GGC, GGA, GGG; leucine and serine likewise have several codons. Often, these codons differ in the third base, the wobble position, so changes there may not alter the amino acid and the protein remains the same.

This concept explains why a single amino acid can arise from different codons, and why mutations in the third base sometimes have no effect on the protein. It also reflects that codons are read in a fixed, non-overlapping reading frame, so no codon overlaps with the next one.