What does the transcriptome refer to?

The transcriptome refers specifically to the complete set of RNA molecules, particularly messenger RNAs (mRNAs), that are produced in a specific cell or tissue type at a given time. This concept encompasses all the transcripts that are being expressed, reflecting the genes that are actively being transcribed into RNA and subsequently translated into proteins. The transcriptome is highly dynamic and can vary between different cell types, developmental stages, or environmental conditions, making it a crucial factor in understanding gene expression and cellular function.

While the complete set of proteins produced by a cell relates to proteomics, and the DNA sequences expressed pertain to genomic studies, these definitions do not encapsulate the concept of the transcriptome. The average number of transcripts in a cell does not capture the full complexity and variety of the RNA molecules present, focusing instead on a quantitative measure rather than a comprehensive overview. Therefore, focusing on mRNA transcripts gives a clear picture of the active gene expression profile in a specific context.