Question

Which of the following is incorrect about a microarray?

(a) It is a slide attached with a high-density array of immobilized DNA oligomers representing the entire genome of the species under study

(b) Array of immobilized DNA oligomers cannot be cDNAs

(c) Each oligomer is spotted on the slide and serves as a probe for binding to a unique complementary cDNA

(d) It is the most commonly used global gene expression profiling method

The question was asked during an interview.

The doubt is from Microarray-Based Approaches topic in section Functional Genomics & Proteomics of Bioinformatics

Answer 1

The correct answer is:

(b) Array of immobilized DNA oligomers cannot be cDNAs

This statement is incorrect because, in a microarray, the array of immobilized DNA oligomers can indeed be cDNAs. In fact, cDNAs are often used in microarrays as they represent the complementary DNA sequences that are synthesized from mRNA, which provides insights into gene expression. The immobilized DNA oligomers on a microarray slide can be either cDNAs or short oligonucleotides that represent genes or specific regions of the genome.

Here's a quick clarification of the other options:

• (a) is correct: A microarray is typically a slide with a high-density array of immobilized DNA oligomers, often representing the entire genome of the species being studied.
• (c) is correct: Each oligomer on the array acts as a probe that binds to complementary cDNA or RNA sequences.
• (d) is correct: Microarrays are indeed one of the most commonly used methods for global gene expression profiling.

So, the incorrect statement is (b).