DNA Microarray Technique: Applications

The DNA microarray technique is a powerful tool primarily used for two main purposes:

• Gene Expression Analysis: Measuring the activity of thousands of genes simultaneously by quantifying their corresponding messenger RNA (mRNA) levels.
• Genotyping and Variation Detection: Identifying genetic variations, such as single nucleotide polymorphisms (SNPs), between individuals or samples.

Understanding Microarray Limitations

Based on these typical applications, let's evaluate the options provided:

• A. Detection of mRNA: This is a primary and typical use of DNA microarrays for gene expression studies.
• B. Detection of tRNA: While tRNA plays a vital role in protein synthesis, its detection and quantification are not a typical application for standard DNA microarrays. Specialized techniques are usually employed.
• C. Detection of rRNA: Ribosomal RNA (rRNA) is crucial for ribosome structure but, like tRNA, is generally not the target for typical gene expression or variation analysis using microarrays.
• D. Genotyping: This is a well-established and typical application of DNA microarrays.
• E. Detects variant gene sequence limited to SNP: While microarrays excel at detecting SNPs (a type of variant gene sequence), the wording might imply a focus narrower than the broadest application of variation analysis. However, compared to tRNA and rRNA detection, analyzing genetic variations (including SNPs) is considered a typical use. Given the provided options and correct answer, it's implied that the specific limitation mentioned in E makes it fall outside the *most typical* uses alongside B and C.

Therefore, the DNA microarray technique is typically not used for the detection of tRNA (B) and rRNA (C). The option suggesting B, C, and E implies these are the least typical applications among the choices.

Conclusion: The correct answer groups the non-typical applications.