1. KEY CONCEPT Translation converts an mRNA message into a polypeptide, or protein.

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 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. Amino acids are coded by mRNA base sequences.
Translation converts mRNA messages into polypeptides.
A codon is a sequence of three nucleotides that codes for an amino acid.
codon for
methionine (Met)
leucine (Leu)

5. The genetic code matches each codon to its amino acid or function.
Each reading frame gives a codon
The genetic code matches each RNA codon with its amino acid or function.
three stop codons
one start codon, codes for methionine

6. A change in the order in which codons are read changes the resulting protein.
Regardless of the organism, codons code for the same amino acid.

7. Amino acids are linked to become a protein.
An anticodon is a set of three nucleotides that is complementary to an mRNA codon.
An anticodon is carried by a tRNA.

8. Ribosomes consist of two subunits.
The large subunit has three binding sites for tRNA.
The small subunit binds to mRNA.

9. For translation to begin, tRNA binds to a start codon and signals the ribosome to assemble.1
A complementary tRNA molecule binds to the exposed codon, bringing its amino acid close to the first amino acid.

10. 2 The ribosome helps form a peptide bond between the amino acids.
The ribosome pulls the mRNA strand the length of one codon.

11. 3 The now empty tRNA molecule exits the ribosome.
A complementary tRNA molecule binds to the next exposed codon.
Once the stop codon is reached, the ribosome releases the protein and disassembles.

12. Name the parts! 1. Amino acid 2. Peptide bond
3. Ribosome- large subunit
4. tRNA
8. Anticodon
7. mRNA
6. Ribosome- small subunit
5. Reading frame/binding site (start codon)

13. This polypeptide is 5 amino acids long

14. Practice Problem Threonine T G A A C U U G A DNA mRNA codon
tRNA anticodon
Amino Acid
Threonine
T G A
A C U
U G A

15. Practice Problem Lysine T T C A A G U U C DNA mRNA codon
tRNA anticodon
Amino Acid
Lysine
T T C
A A G
U U C