Degeneracy of the Genetic Code

Steps:

• Identify codons per amino acid from the table: methionine (1), isoleucine (3), cysteine (2), tryptophan (1).
• Calculate total DNA sequences by multiplying codon options for each position in the sequence.
• For methionine-isoleucine-cysteine-tryptophan: 1 × 3 × 2 × 1.
• Result: 6 possible sequences.

Why C is correct:

• Genetic code degeneracy means multiple codons can specify one amino acid; total sequences equal the product of codon variants per position.

Why the others are wrong:

• A: Ignores isoleucine's 3 codons, yielding only 2 (1×1×2×1).
• B: Accounts for cysteine and isoleucine partially (2×2), but misses full multiplicity.
• D: Overcounts by adding extraneous factors, exceeding the 1×3×2×1 product.

Final answer: C