1. TRANSLATION Protein Synthesis
Assembling Amino Acids

2. Protein Structure
Proteins (polymers) are composed from many amino acids (monomers) which create covalent peptide bonds during a dehydration synthesis or condensation reaction.
The specific sequence of amino acids determines which protein is created.
oxytocin
cys-tyr-gln-asn-cys-pro-leu-gly
somatostatin
ala-gly-cys-lys-asn-phe-phe-trp-lys-phe-thr-ser-cys

3. Amino Acid Structure A centrally located carbon with four attachments:
hydrogen atom
carboxyl group (–COOH)
amino group (–NH2)
R group
(distinguishes between
amino acids)
Amino acids bond during dehydration synthesis or condensation reactions

4. How do we get from DNA to proteins
How do we get from DNA to proteins? DNA – RNA – proteins transcription translation (in nucleus) (in cytoplasm at ribosomes)
First transcription occurs which makes the RNA
Then, translation occurs which matches the amino acids to the correct sequence of RNA using the Genetic Code
Holt Biology Interactive Tutor 6-6
TRANSLATION

5. The Genetic Code
It is the matching of the RNA sequence to the correct amino acid to make proteins.
It is based on codons, 3 nitrogen bases next to each other on an mRNA chain.
The 3 bases on a tRNA are called the anticodon, they are the complement of the codon.

6. The Genetic Code continued...
There are 64 codons, but 20 amino acids, so each amino acid has multiple codons that code for it.
There are 4 special start/stop codons that signal the beginning or end of a protein chain.
START – AUG
STOP – UAA, UAG, UGA

7. Start/Stop Codons
AUG is the start codon. A protein will not be made unless this is at the beginning. It also codes for methionine.
UAA, UAG, and UGA code for the end of protein.
Protein synthesis will not start or stop unless these are read.

8. Genetic Code Square

9. Genetic Code Circle

10. Translation
Begins when mRNA leaves the nucleus through nuclear pores and migrates to the ribosomes.
tRNA will provide the transportation of the correct amino acids to the ribosomes.

12. Translation Step 1: Ribosome attachs to the start codon (AUG)
of the mRNA.
Step 2: A tRNA w/ the anticodon of UAC and a
methionine binds to the mRNA inside the
ribosome.
Step 3: At the 2nd binding site, the next codon is
read and a tRNA is attached
Step 4: When the second tRNA attaches, the amino
acids attached to the 1st tRNA releases from
the tRNA and binds to the new amino acid
with a peptide bond

13. Translation (continued)
Step 5: The
1st tRNA is
released and
the ribosome
moves to
another codon
(3 nucleotides).
Step 6: When a stop codon is reached, translation stops and the ribosome releases the mRNA and the created protein.

14. Animations

15. Protein synthesis analogy