Gene expression system

Gene expression is the process by which the genetic code - the nucleotide sequence - of a gene is used to direct protein synthesis and produce the structures of the cell. Genes that code for amino acid sequences are called as Structural genes. The process of gene expression involves two main stages as Transcription: the production of messenger RNA (mRNA) by the enzyme RNA polymerase, and the processing of the resulting mRNA molecule. Translation: the use of mRNA to direct protein synthesis, and the subsequent post-translational processing of the protein molecule. Any step of gene expression may be modulated, from the DNA-RNA transcription step to post-translational modification of a protein.