DNA is considered a universal genetic code. Which statement is true of the genetic code?

• A. The genetic code is composed of only two nucleotides, adenine and thymine.
• B. The genetic code is redundant, meaning multiple codons can code for the same amino acid.
• C. The genetic code is unique to each species, with different codons for the same amino acids.
• D. The genetic code is non-overlapping, meaning each nucleotide is part of multiple codons.

Answer: (B)

Verified step by step guidance

1. Understand that DNA is composed of four nucleotides: adenine (A), thymine (T), cytosine (C), and guanine (G). This means the statement about the genetic code being composed of only adenine and thymine is incorrect.
2. Recognize that the genetic code is universal, meaning it is shared by almost all organisms, which contradicts the statement that it is unique to each species.
3. Learn that the genetic code is redundant. This means that multiple codons (triplets of nucleotides) can code for the same amino acid. For example, the amino acid leucine is coded by six different codons.
4. Understand that the genetic code is non-overlapping, meaning each nucleotide is part of only one codon at a time, not multiple codons.
5. Conclude that the correct statement about the genetic code is that it is redundant, allowing for multiple codons to code for the same amino acid, which provides a buffer against mutations.