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
AUG codon: Activates the ribosome
UAA or UAG or UGA codon: deactivates the ribosome

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 read by a ribosome
Ribosome reads one codon at a time
AUG = methionine
GCU = alanine
tRNA carries over the proper amino acid
tRNA anticodon matches with the mRNA codon
Prevents delivery of wrong amino acid
One by one, amino acids are linked together
Translation ends when a “stop” codon is reached
What just happened?: A ribosome made a 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. Six GAU AUG CCG AGU CCA GGA UCU UGA UAC GGC UCA GGU CCU AGA Ribosome
Questions to answer:
In order, list the amino acids that will be delivered to this ribosome.
What is the anticodon of each codon?
When finished, how many amino acids in size is this protein?
tRNA
UAC
tRNA
GGC
tRNA
UCA
tRNA
GGU
tRNA
CCU
tRNA
AGA
Six
Methionine
(MET)
Proline
(PRO)
Serine
(SER)
Proline
(PRO)
Glycine
(GLY)
Serine
(SER)
Ribosome
tRNA
UAC
tRNA
GGC
tRNA
UCA
tRNA
GGU
tRNA
CCU
tRNA
AGA
ignore
GAU AUG CCG AGU CCA GGA UCU UGA
start
stop

9. Threonine T G A A C U U G A DNA mRNA codon tRNA anticodon 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. Lysine T T C A A G U U C DNA mRNA codon tRNA anticodon 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. C A G U C A glycine DNA mRNA codon tRNA anticodon 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?
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 #8-11.

13. mRNA codes

14. mRNA codes