1. The ‘redundant’ code

2. The redundant code
DNA has four different bases, but a 3-base (triplet) code.

3. The redundant code
DNA has four different bases, but a 3-base (triplet) code.
There are 64 possible different triplet combinations of the four bases.

4. The redundant code
DNA has four different bases, but a 3-base (triplet) code.
There are 64 possible different triplet combinations of the four bases.
Triplets in DNA are transcribed as codons in mRNA.

5. The redundant code
DNA has four different bases, but a 3-base (triplet) code.
There are 64 possible different triplet combinations of the four bases.
Triplets in DNA are transcribed as codons in mRNA.
Therefore there are 64 different possible codons.

6. The redundant code
UAA, UAG and UGA are the stop codons – this is where translation is stopped and the polypeptide chain is released from the ribosome.

7. The redundant code
UAA, UAG and UGA are the stop codons – this is where translation is stopped and the polypeptide chain is released from the ribosome.
With 60 possible codons, most of the 20 amino acids are coded for by more than one codon.

8. The redundant code
UAA, UAG and UGA are the stop codons – this is where translation is stopped and the polypeptide chain is released from the ribosome.
With 60 possible codons, most of the 20 amino acids are coded for by more than one codon.
Eg – CCU, CCC, CCA, and CCG all code for the amino acid ‘pro’ (proline).

9. The redundant code
UAA, UAG and UGA are the stop codons – this is where translation is stopped and the polypeptide chain is released from the ribosome.
With 60 possible codons, most of the 20 amino acids are coded for by more than one codon.
Eg – CCU, CCC, CCA, and CCG all code for the amino acid ‘pro’ (proline).
This makes the code degenerate and therefore redundant.

10. Degenerate – a code in which several code words have the same meaning
Degenerate – a code in which several code words have the same meaning. The genetic code is degenerate because there are many instances in which different codons specify the same amino acid.

11. Degenerate – a code in which several code words have the same meaning
Degenerate – a code in which several code words have the same meaning. The genetic code is degenerate because there are many instances in which different codons specify the same amino acid.
Redundant – the genetic code is redundant because many amino acids can be specified for by more than one codon.

12. Advantages of this
If a mistake occurs in transcription (a mutation) there is a chance that the new codon will still code for the same amino acid, so the protein remains the same.