Final answer:
DNA microarrays contain a. single-stranded DNA fixed on a solid surface to detect and quantify complementary DNA or RNA sequences through hybridization.
Step-by-step explanation:
DNA microarrays are a technology used in molecular biology and biotechnology to measure the expression levels of many genes simultaneously or to genotype multiple regions of a genome. The correct answer to what DNA microarrays contain is a. single-stranded DNA. DNA microarrays consist of a solid surface onto which single-stranded DNA sequences are fixed in an orderly arrangement. These sequences are known as probes and are complementary to the target DNA sequence or mRNA to be detected.
Microarrays rely on the principle of nucleic acid hybridization between the fixed single-stranded DNA on the microarray and a fluorescently labeled single-stranded DNA sample. This process allows for the identification and quantification of the sample DNA sequences that are complementary to the probes on the microarray.
It's important to understand that, in cells, DNA naturally exists as a double-stranded helix, with base pairing between the two strands. However, for the purpose of a microarray, the DNA must be denatured or separated into single strands to enable hybridization with the labeled DNA or RNA sample.