Question

Which of the following technique(s) can be used to study differential gene expression in two tissues under two different external conditions?
A. Northern hybridization
B. Whole genome RNA sequencing
C. qPCR
D. Semi-quantitative PCR
E. Whole Genome Sequencing
Choose the correct answer from the options given below:

• A. A, B, C and D only
• B. A, C, D and E only
• C. B, C, D and E only
• D. A, B, D and E only

Hint:

If the question asks about "expression," focus on RNA-based techniques. If it asks about "variation" or "SNPs," focus on DNA-based sequencing (WGS).

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
"Differential gene expression" refers to the study of how the transcript levels (mRNA) of genes vary between different cell types, developmental stages, or environmental conditions. Techniques for this study must target the Transcriptome (RNA), not the Genome (DNA).

Step 2: Detailed Explanation:
Let us evaluate the techniques:
- Northern hybridization (A): A traditional method where RNA is separated by size and detected using specific probes. It allows for comparing the abundance of a specific mRNA across tissues or conditions.
- Whole genome RNA sequencing (B) [RNA-Seq]: A modern, high-throughput method that sequences and quantifies all transcripts in a sample. It is the most powerful tool for discovering new differentially expressed genes.
- qPCR (C): Quantitative PCR is the "gold standard" for measuring the precise fold-change of specific gene transcripts.
- Semi-quantitative PCR (D): An older method that estimates relative transcript levels by observing band intensity on an agarose gel during the linear phase of PCR.
- Whole Genome Sequencing (E): This technique sequences the DNA of an organism to find mutations or variations in the blueprint. It does not provide information about which genes are "turned on" (expressed) at a given time.
Therefore, A, B, C, and D are valid expression study techniques.

Step 3: Final Answer:
Techniques A, B, C, and D are used for RNA analysis, while E is for DNA analysis. Option 1 is correct.