 Attachment of the mRNA strand to the ribosome initiates the production of the protein coded for by the mRNA strand.Therefore, the profile of active genes in a cell is reflected in the presence or absence of corresponding proteins and mRNA strands in the cell's cytoplasm, and antigen proteins present on the cell's outer membrane.Discovering, determining and classifying cells as to their type therefore involves detecting and measuring the type and amount of specific protein and RNA molecules present in the cells.