Describe an rDNA experiment in two or three sentences. Use the following terms: intron, exon, DNA, mRNA, cDNA, RNA polymerase, reverse transcriptase.

Genes are composed of exons, which code for proteins, and introns, non-coding sequences removed during mRNA processing. Understanding this distinction is crucial for interpreting how mRNA and cDNA represent only the exon sequences of a gene.

RNA polymerase synthesizes mRNA from a DNA template by transcribing only the exons and introns present in the gene. This process produces a primary mRNA transcript that undergoes splicing to remove introns before translation.

Reverse transcriptase is an enzyme that converts processed mRNA back into complementary DNA (cDNA), which lacks introns. This cDNA can be used in recombinant DNA experiments to clone genes without introns, facilitating gene expression studies.