Thus, the transcriptome is a complex and dynamic structure that is determined by and sensitive to the stages of the cell cycle and organism development, cell and tissue types, and the effects of external signals during both transcriptional and post-transcriptional processes. The study of the transcriptome is the main subject of transcriptomics, also referred to as gene expression profiling or the measuring of the activity (at the expression level) of thousands of genes at once by means of high-throughput techniques based on microarray technology or direct sequencing of the RNA. The main purpose of transcriptomics is to investigate transcripts and their differential temporal and spatial distribution in different cell types and tissues with the aim of understanding the molecular mechanisms of their differentiation, development, and functioning. Whole transcriptome profiling (or whole genome expression profiling) provides information about multiple differences in the expression of a set of genes under various conditions, with the purpose of, for example, distinguishing different type of cells or investigating cell/tissue response to treatment. Whole transcriptome profiling has particular value in studies of the genome functioning in
