Editing Transcriptome (section)

==Scope of study==
In the human genome, all genes get transcribed into RNA because that's how the molecular gene is defined. (See [[Gene]].) The transcriptome consists of coding regions of mRNA plus non-coding UTRs, introns, non-coding RNAs, and spurious non-functional transcripts.

Several factors render the content of the transcriptome difficult to establish. These include [[alternative splicing]], [[RNA editing]] and alternative transcription among others.<ref name="scitable">{{cite journal|url=https://www.nature.com/scitable/topicpage/transcriptome-connecting-the-genome-to-gene-function-605/#|title=Transcriptome: Connecting the Genome to Gene Function|first=Jill|last=U. Adams|journal=[[Nature Education]]|volume=1|issue=1|page=195|year=2008}}</ref> Additionally, transcriptome techniques are capable of capturing transcription occurring in a sample at a specific time point, although the content of the transcriptome can change during differentiation.<ref name="pertea" /> The main aims of transcriptomics are the following: "catalogue all species of transcript, including mRNAs, non-coding RNAs and small RNAs; to determine the transcriptional structure of genes, in terms of their start sites, 5′ and 3′ ends, splicing patterns and other post-transcriptional modifications; and to quantify the changing expression levels of each transcript during development and under different conditions".<ref name="biblio1">{{cite journal|title=RNA-Seq: a revolutionary tool for transcriptomics|first1=Zhong|last1=Wang|first2=Mark|last2=Gerstein|first3=Michael|last3=Snyder|journal=[[Nature Reviews Genetics]]|doi=10.1038/nrg2484|pmid=19015660|pmc=2949280|date=January 2009|volume = 10|issue = 1|pages=57–63}}</ref>

The term can be applied to the total set of transcripts in a given [[organism]], or to the specific subset of transcripts present in a particular cell type. Unlike the [[genome]], which is roughly fixed for a given cell line (excluding [[mutation]]s), the transcriptome can vary with external environmental conditions. Because it includes all mRNA transcripts in the cell, the transcriptome reflects the [[gene]]s that are being actively [[gene expression|expressed]] at any given time, with the exception of mRNA degradation phenomena such as [[attenuator (genetics)|transcriptional attenuation]]. The study of [[transcriptomics]], (which includes [[expression profiling]], [[splice variant analysis]] etc.), examines the expression level of RNAs in a given cell population, often focusing on mRNA, but sometimes including others such as tRNAs and sRNAs.