In a protein molecule amino acids are joined together by peptide bonds. In the process of protein synthesis also known as translation of mRNA, the amino acids are added sequentially in a specific number. The protein synthesizing mechanism involves the following steps:
The formation of RNA complementary to a DNA strand is called transcription. In this process, the RNAs required for protein synthesis are synthesized on DNA strands. This reaction is catalyzed by the enzyme RNA polymerase.
The enzyme, RNA polymerase I, II, III are involved in the synthesis of rRNA (ribosomal RNA) mRNA (messenger RNA) and tRNA (transfer RNA) respectively in the eukaryotes. In prokaryotes only one type of RNA polymerase is present to synthesize all the three classes of RNA.
In the DNA double helix, one of the strands serves as a template to produce RNA. The RNA produced by transcription is inactive and is called pre-RNA. They become active after further processing. All these RNA are processed through chemical reactions and structural modifications.