DNA & Translation

1. DNA & Translation

2. Gene: section of DNA that creates a specific protein Approx 25,000 human genes Proteins are used to build cells and tissue Protein synthesis involves two processes: 1) Transcription 2) Translation DNA and Translation

3. Transcription Review • Transcription takes place in the nucleus • 1) DNA double helix is broken apart • 2) mRNA nucleotides match up • 3) Finished mRNA detaches, and moves to a ribosome

4. Codon: Combination of 3 mRNA nucleotides Each mRNA codon matches with 1 of 20 amino acids Codon AAA = Lysine Codon GUU = Valine Codon AUG = Methionine (Start) Codons UAA or UAG or UGA = Stop The Genetic Code

5. Translation Overview • Defined: Process of making proteins • Step 1: mRNA enters ribosome • Step 2: Ribosome reads one mRNA codon at a time • Step 3: tRNA delivers amino acids until a protein is created

6. Translation begins when the mRNA codon “AUG” is reached Each mRNA codon matches with a specific amino acid AUG = methionine GCU = alanine tRNA carries over the proper amino acid tRNA anticodon matches with the mRNA codon One by one, amino acids are linked together Translation ends when a “stop” codon is reached End result: Polypeptide (protein) Translation Details

7. Translation Animation mRNA

8. This polypeptide is 5 amino acids long

9. Practice Problem Threonine T G A A C U U G A

10. Practice Problem Lysine T T C A A G U U C

11. Interactive Protein Synthesis

12. Quick Review • Every DNA gene codes for a specific protein • Codon/anticodon match guarantees proper amino acid • Many amino acids link to make one protein video clip Fast forward 50 seconds