Which of the following is the best definition of a gene?

• A. An RNA molecule transcribed from a sequence of DNA.
• B. A stretch of DNA that can be transcribed.
• C. A sequence of DNA where the process of transcription ends.
• D. A sequence of DNA that encodes a product like an RNA or a protein.
• E. A sequence of DNA where the process of transcription begins.

Answer: (D)

Verified step by step guidance

1. Understand that a gene is a fundamental unit of heredity in living organisms.
2. Recognize that genes are composed of DNA sequences that contain the instructions for building proteins or RNA molecules.
3. Identify that the primary function of a gene is to encode a product, which can be either an RNA molecule or a protein.
4. Note that transcription is the process by which a gene's DNA sequence is copied into RNA, which can then be used to produce proteins.
5. Conclude that the best definition of a gene is a sequence of DNA that encodes a product like an RNA or a protein, as it encompasses the gene's role in encoding functional molecules.