Transcriptome

The transcriptome is the set of all RNA molecules (transcripts) in a cell or a population of cells. It includes all of the functional RNA molecules and all other transcripts that may arise by spurious transcription or transcription of non-functional regions such as pseudogenes or virus fragments. A major goal of modern molecular biology is to determine which transcripts are functional and which ones are junk RNA.

The term transcriptome is a portmanteau of the words transcript and genome; it is associated with the process of transcript production during the biological process of transcription. The functional part of the transcriptome is dynamic — it changes with cell type, developmental stage, environment, and stimuli — and therefore represents the active gene expression state rather than the static DNA sequence (genome).

Eukaryotic transcriptomes tend to be more complex than bacterial transcriptomes and the transcriptomes of multicellular eukaryotes are even more complex than those of unicellular eukaryotes.

Etymology and history

The word transcriptome is a portmanteau of the words transcript and genome. It appeared along with other neologisms formed using the suffixes -ome and -omics to denote all studies conducted on a genome-wide scale in the fields of life sciences and technology. As such, transcriptome and transcriptomics were one of the first words to emerge along with genome and proteome. The first study to present a case of a collection of a cDNA library for silk moth mRNA was published in 1979. The first seminal study to mention and investigate the transcriptome of an organism was published in 1997 and it described 60,633 transcripts expressed in S. cerevisiae using serial analysis of gene expression (SAGE).