1. Transcription &
Translation

2. Transcription DNA  mRNA (occurs in the nucleus)
RNA polymerase binds to & separates the DNA strands at promoter sites
Promoter - 3 base sequence that serves as a starting and ending points for RNA to be made

3. Transcription
RNA polymerase uses one strand of DNA as a template to make the complementary strand of mRNA

4. DNA contains…
Introns – nucleotide sequences that do NOT code for proteins
Exons – nucleotide sequences that do code for proteins

5. RNA polymerase copies both introns and exons, but before mRNA leaves the nucleus…
Introns are cut out of the sequence
Exons are spliced (glued) back together to form the final mRNA

6. mRNA travels to the ribosomes (outside of nucleus)

7. Translation

8. Translation mRNA  protein (occurs on ribosomes)
mRNA attaches to a ribosome
Starting at codon “AUG,” ribosome reads each codon
Codon = 3 nucleotides

9. Translation
For each codon, an amino acid is brought into the ribosome by tRNA
Each tRNA molecule carries only one kind of amino acid
Each tRNA has the anticodon, that is complementary to one mRNA codon

10. Translation
A peptide bond forms between each amino acid as it is brought into the ribosome  polypeptide chain
tRNA is released
Polypeptide chain stops growing when the ribosome reaches a stop codon on the mRNA

11. Translation
Polypeptide (protein) & mRNA are released from the ribosome

12. Review

13. Important Facts: 3 nucleotides = 1 codon = 1 amino acid
64 codon combinations, but only 20 different amino acids
The properties of proteins are determined by sequence of amino acids