Which of the following best describes a codon in the context of nucleic acids?

• A. A sequence of nucleotides that forms the backbone of $DNA$
• B. A sequence of nucleotides that signals the end of transcription
• C. A sequence of nucleotides that initiates $DNA$ replication
• D. A sequence of three nucleotides that codes for a specific amino acid

Answer: (D)

Verified step by step guidance

1. Understand that a codon is a fundamental concept in molecular biology, specifically in the context of nucleic acids like DNA and RNA.
2. Recognize that a codon consists of a sequence of three nucleotides. These nucleotides are the building blocks of nucleic acids.
3. Each codon corresponds to a specific amino acid or a stop signal during the process of protein synthesis, which occurs during translation.
4. In the genetic code, the sequence of nucleotides in a codon determines which amino acid will be added next during protein synthesis.
5. Therefore, the best description of a codon is 'A sequence of three nucleotides that codes for a specific amino acid.'