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 a gene is a sequence of DNA that contains the necessary information to produce a functional product, which can be either an RNA molecule or a protein.
3. Differentiate between the options given: an RNA molecule transcribed from DNA is a product of gene expression, not the gene itself.
4. Identify that a stretch of DNA that can be transcribed refers to the process of gene expression but does not define a gene.
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 function and purpose of a gene in biological systems.