In the context of DNA-based technology, what is a diagnostic tracer?

• A. An enzyme that synthesizes new DNA strands during replication.
• B. A protein that binds to DNA to regulate gene expression.
• C. A labeled DNA or RNA molecule used to detect the presence of a specific genetic sequence in a sample.
• D. A chemical used to break down DNA into its nucleotide components.

Answer: (C)

Verified step by step guidance

1. Understand the term 'diagnostic tracer' in the context of DNA-based technology. A diagnostic tracer is a labeled DNA or RNA molecule designed to detect specific genetic sequences in a sample.
2. Recognize that the tracer works by hybridizing (binding) to its complementary sequence in the sample, allowing researchers to identify the presence of the target genetic material.
3. Learn about the labeling process: Diagnostic tracers are often tagged with radioactive isotopes, fluorescent dyes, or other markers to make the detection process visible or measurable.
4. Differentiate diagnostic tracers from other molecules mentioned in the problem, such as enzymes (which synthesize DNA), regulatory proteins (which bind DNA to control gene expression), or chemicals that degrade DNA.
5. Understand the application: Diagnostic tracers are widely used in techniques like Southern blotting, Northern blotting, and in situ hybridization to study genetic material and diagnose diseases.