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
Ribosome reads codons 1 at a time
Codon AUG = Methionine (Start)
Codon GUU = Valine
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 (starting with the mRNA codon AUG)
Step 3: tRNA delivers amino acids until a stop codon (one of 3) is reached = a completed protein.

6. Translation Details
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

7. Now the codon and anticodon match
Now the codon and anticodon match. This ensures the proper amino acid (serine) is delivered.
This is why the anticodon is important!
Because the codon and anticodon don’t match, the wrong amino acid will not be delivered.

8. GAU AUG CCG AGU CCA GGA UCU UGA
Questions to answer:
List the amino acids that will be delivered to this ribosome.
2) What is the anticodon of each codon?
3) When finished, how many amino acids in size is this protein?
Methionine
Pro-line
Serine
Pro-line
Gly-cine
Serine
STOP CODON
Ribosome
tRNA
UAC
tRNA
GGC
tRNA
UCA
tRNA
GGU
tRNA
CCU
tRNA
AGA
tRNA
ACU
GAU AUG CCG AGU CCA GGA UCU UGA

9. Always use mRNA to find the amino acid
Practice Problem
Always use mRNA to find the amino acid
DNA
mRNA codon
tRNA anticodon
Amino Acid
Threonine
T G A
A C U
U G A

10. Always use mRNA to find the amino acid
Practice Problem
Always use mRNA to find the amino acid
DNA
mRNA codon
tRNA anticodon
Amino Acid
Lysine
T T C
A A G
U U C

11. Always use mRNA to find the amino acid
Practice Problem
Always use mRNA to find the amino acid
DNA
mRNA codon
tRNA anticodon
Amino Acid C A G U C A
glycine

12. REview Define transcription? Translation?
Where does transcription take place? Translation?
What are genes and how are they different from chromosomes?
How many nucleotides make a codon?
The anticodon can be found on which object?
The anticodon must match the ____________.
Place the following steps in order from start to finish:
a. Proteins are assembled
b. Ribosome reads a codon one at a time
c. mRNA arrives at the ribosome
d. tRNA delivers amino acids to the ribosome
7) Be able to solve practice problems similar to the three examples on slides # 9 -11