Gene Expression

The Respiratory System

In bacteria, mRNA generally does not undergo modification following transcription while tRNA is processed in bacteria with cleavage, addition, and modification. In eukaryotes complex processing occurs of both tRNA and mRNA. Nearly all mRNA primary transcripts in eukaryotes are spliced. Introns are excised. Variations of mRNA are possible on the same theme to produce the members of protein families, a prominent example being variations of antibody molecules.