1. Protein Synthesis: Translation
Miss Richardson
SBI4U

2. Purpose: To translate mRNA and use that information to build protein
Location: cytoplasm
Stages:
Initiation
Elongation
Termination
Translation

3. tRNA 2D clover-shaped molecule Two functional regions:
Anticodon loop – 3 nucleotides complementary to specific mRNA codon
Acceptor stem – amino acid attached by enzyme aminoacyl-tRNA synthetase
tRNA

4. Made up of proteins which have rRNA bound to them, forming a small subunit and large subunit
Site of amino acid assembly
Contains a P-site (peptide), A-site (amino acid) and E-site (exit)
Ribosomes

5. Near the start codon (AUG), initiation factors assemble small ribosomal subunits on the mRNA
tRNA carrying methionine (with anticodon UAC) binds to the start codon
The large ribosomal subunit joins
P-site: contains tRNA with growing amino acid chain
A-site: accepts next tRNA to add amino acid (charged)
E-site: contains tRNA that has delivered amino acid (uncharged)
Initiation

6. Elongation factors assist new tRNA molecules in binding to complementary mRNA codon
Peptide bonds form between amino acids through a condensation reaction (ATP needed!)
mRNA moves along in the 5’-3’ direction building the amino acid chain
Elongation

7. Elongation occurs until a stop codon is reached on the mRNA strand
Release factors bind to A-site on ribosome, dismantling the subunits
The new peptide chain is released
mRNA transcript and ribosomal subunits are recycled
Termination