Template strand of the DNA is transcribed to mRNA. RNAP type II or B is the enzyme synthesizing RNA in mammals. It is susceptible to amanitin. A transcription bubble contains RNA polymerase, DNA and nascent RNA. Termination of transcription can be Rho factor dependent or independent. Post-transcriptional processing of the primary RNA transcript includes poly-A tailing at 3’ end, capping at 5’ end, methylation and intron splicing. Ribozymes are enzymes made up of RNA. Examples are RNAse P, peptidyl transferase and spliceosomes. Reverse transcriptases are RNA dependent DNA polymerases. They synthesise a DNA strand using RNA as their template. Retroviruses such as HIV and tumor viruses possess this enzyme. Transfer RNA (tRNA) or soluble RNA (sRNA) is the adapter molecule between transcription and translation. Each amino acid has a specific tRNA. The triplet sequence on the anticodon arm of the tRNA is complementary to the codon triplet on the mRNA. Six important characteristics of the genetic code are that it is triplet, universal, degenerate, non-overlapping, non-punctuated and exhibit wobbling. Three terminator codons are UAA, UAG and UGA. Four high energy phosphate bonds are required for the formation of one peptide bond, two for initial activation, one for EF-1 step and one for EF-2 step. Post-translational processing of proteins includes removal of the signal sequences, gamma carboxylation, methylation, acylation, subunit aggregation ad phosphorylations. Clinically useful protein synthesis inhibitors are Streptomycin, Chloramphenicol, Tetracyclines; Erythromycin Chaperones are proteins that govern protein folding. Improper protein folding may lead to Prion diseases.