Transcriptome broadly refers to the collection of all transcription products in a cell under a certain physiological condition, including messenger RNA, ribosomal RNA, transfer RNA and non-coding RNA; narrowly refers to the collection of all mRNAs.
  The transcriptional process of synthesizing RNA using DNA as a template is the first step in gene expression and a key link in the regulation of gene expression. By gene expression, we mean the whole process of transforming the genetic information carried by genes into a recognizable phenotype. Unlike the genome, the definition of the transcriptome contains temporal and spatial qualifications. The gene expression of the same cell is not identical at different growth periods and growth environments.