cDNA Library

Introns

Segments of DNA that do not code for useful proteins.

Exons

Segments of DNA that code for proteins.

cDNA library

A library of eukaryotic genes in which all intron segments have been removed.

Reverse transcriptase

An enzyme that synthesizes complementary DNA from an mRNA template.

Pre-mRNA

The initial transcript that contains both introns and exons before processing.

RNA splicing

The process of removing introns from pre-mRNA and joining exons to form mature mRNA.

Transcription

The process of copying a segment of DNA into RNA.

DNA polymerase

An enzyme that synthesizes a new strand of DNA complementary to the template strand.

Poly-A tail

A stretch of adenine nucleotides added to the 3' end of mRNA for stability and export from the nucleus.

Eukaryotic cells

Cells that contain a nucleus and other organelles, and have DNA with introns and exons.

Prokaryotic cells

Cells that do not have a nucleus, and typically contain DNA without introns.

Complementary DNA (cDNA)

DNA synthesized from an mRNA template that does not include introns.