1. Step 2 of protein Synthesis
Translation
Step 2 of protein Synthesis

3. Once the mRNA enters the cytoplasm, it is ready to be translated into a protein
Ribosomes bind to the mRNA, recognizing the 5’ cap and signaling the initiation of translation

4. The Ribosome
Consists of 2 subunits: a large subunit and a small subunit
The 2 subunits bind to the mRNA, clamping it between them
The ribosome then moves along the mRNA in the 5’ to 3’ direction adding amino acids to a growing chain each time it reads a codon

5. Transfer RNA (tRNA)
The ribosome cannot synthesize the polypeptide chain alone, tRNA is involved to deliver the correct amino acid to the polypeptide building site
At one arm of the tRNA, a sequence of 3 bases (anticodon) match the codon of the mRNA
The opposite arm carries the corresponding amino acid

7. Every tRNA molecule carries only one specific amino acid, therefore at least 20 different tRNA’s are required
A tRNA moleucle containing its corresponding amino acid attached to its receptor site at the 3’ end is called aminoacyl-tRNA
The enzyme responsible for adding the amino acids is aminoacyl-tRNA synthetase

8. Elongation of Polypeptide Chain
The start codon AUG is the first codon recognized by the ribosome
AUG codes for methionine, therefore every protein starts with this amino acid
The Ribosome has 3 sites for aminoacyl-tRNA
The A Site (acceptor site): site in the ribosome where the tRNA brings the correct amino acid
The P Site (peptide site): site in the ribosome where peptide bonds are formed
The E Site (exit site): site in the ribosome where tRNA can exit

12. The ribosome will eventually reach a stop codon and dissociate from the mRNA
The polypeptide if formed correctly will continue its journey to becoming a functioning protein (secondary, tertiary, quaternary structure)
The mRNA will get digested and its parts will be reused
Proteins are constantly made incorrectly because there are no proof reading mechanisms
Research the Wobble Hypothesis

13. Homework
Section 7.3 p Answer p. 331 #1, 2, 6, 7 Answer SG p. 101 #2, 3, 4, 6, 7, 8, 10