Lecture 19-20: Protein Synthesis and the Genetic Code and Synthesis of Membrane Proteins Reading Assignment: Chapter 40 and 43, pgs. 452-467 and 505-533; Harper’s Biochemistry (25 th

edition). Objective: To know the major steps in protein synthesis and the RNAs and proteins involved in this

process. To understand the mechanism by which proteins are targeted to specific cimpartments.  I. Genetic code 

A. Three nucleotides make one codon 

B. "Universal" 

C. Degenerate 

D. Commaless II. Translation 

A. Initiation 

B. Elongation 

C. Termination III. Targeting of proteins to specific compartments 

A. Mitochondria 

B. Membranes 

C. Lysosomes 

D. Secretion 

IV. Effect of mutations to the genetic code 

A. Transition vs transversion 

B. Missense 

C. Nonsense 

D. Frameshift V. Post-translational processing  

A. Amino terminal modification 

B. Signal sequences 

C. Modification of individual amino acids 

D. Phosphorylation 

E. Methylation 

F. Addition of carbohydrate side chains 

G. Addition of isoprenyl groups 

H. Addition of prosthetic groups (i.e. biotin addition to heme of cytochrome C)

I. Proteolytic processing 

1. Binding of aminoacyl tRNA to the A site2. Formation of a peptide bond3. Translocation. The two steps in 3 occur simultaneously