Question

Why do DNA chips often contain segments derived from cDNA rather than genomic DNA segments?

Short answer

Non-coding sections are not found in cDNA.

Step-by-step solution

Definition of DNA

Deoxyribonucleic acid is a polymer made of two polynucleotide chains that coil around one another to create a double helix and which contains the genetic material necessary for all known creatures, including many viruses, to develop, function, grow, and reproduce.Nucleic acids include DNA and ribonucleic acid.

Explanation

An RNA transcript's or the DNA encoding it's introns are non-coding segments that are spliced off before the RNA molecule is translated into a protein. Exons are the regions of DNA (or RNA) that code for proteins.

The presence of introns and exons in cDNA makes it a better choice for DNA chips than genomic DNA. Hence, non-coding DNA sections such as introns and exons are worthless in DNA chips.

Therefore, non-coding sections do not exist in cDNA.