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 Ribosome reads codons 1 at a time Codon AUG = Methionine (Start) Codon GUU = Valine 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 read by the ribosome 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 Ensures proper match One by one, amino acids are linked together Translation ends when a “stop” codon is read by the ribosome End result: Protein Translation Details

7. Because the codon and anticodon don’t match, the amino acid serine will simply float away. This prevents incorrect amino acids from being delivered!

8. Methionine Proline Serine Proline Glycine Serine Ribosome tRNA UAC tRNA GGC tRNA UCA tRNA GGU tRNA CCU tRNA AGA GAU AUG CCG AGU CCA GGA UCU UGA

9. Always use mRNA to find the amino acid Practice Problem Threonine T G A A C U U G A

10. Practice Problem Always use mRNA to find the amino acid Lysine T T C A A G U U C

11. Always use mRNA to find the amino acid Practice Problem C C A G G U C C A glycine

12. mRNA codes

13. mRNA codes