Question

Expression of a gene can be measured by

• A. Amplifying the gene by PCR
• B. Reverse transcribing the cDNA of the gene followed by polymerization
• C. Hybridizing the gene with a specific probe
• D. Cloning the gene in a heterologous system

Hint:

This entire two-step process is commonly known as RT-PCR (Reverse Transcription Polymerase Chain Reaction), which is the gold standard for measuring gene expression.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Gene expression is analyzed by measuring the abundance of transcribed messenger RNA (mRNA) in a given tissue sample.

Step 2: Detailed Explanation:
- Standard PCR only amplifies genomic DNA and does not reflect transcription rates.
- To measure gene expression, total RNA is first isolated.
- This RNA is reverse transcribed into complementary DNA (cDNA) using the enzyme reverse transcriptase.
- The resulting cDNA is then amplified using quantitative PCR (RT-qPCR) or semi-quantitative PCR.
- The quantity of amplified product is directly proportional to the original abundance of mRNA, providing an accurate measure of gene expression.

Step 3: Final Answer:
Gene expression is measured by reverse transcribing mRNA into cDNA followed by PCR amplification.