1. DNA &
Translation

2. DNA and Translation
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

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. The Genetic Code 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

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 Details
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)

7. This polypeptide is 5 amino acids long

8. Practice Problem
DNA
mRNA
tRNA
Amino Acid
Threonine
T G A
A C U
U G A

9. Practice Problem
DNA
mRNA
tRNA
Amino Acid
Lysine
T T C
A A G
U U C

10. 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