The Genetic Code is Universal and Degenerate
- The genetic code is the set of rules by which the information in DNA is translated into proteins.
- It is nearly universal, degenerate, and specific, ensuring that the right proteins are made at the right time.
Definition
Degenerate
Multiple codons code for the same amino acid, reducing the impact of mutations.
Definition
Universal
Nearly all organisms use the same code, allowing for genetic engineering and biotechnology advances.
Why a Triplet Code?
- DNA is made up of four bases: adenine (A), thymine (T), cytosine (C), and guanine (G).
- Proteins, however, are made from 20 different amino acids.
- So, how does a sequence of four bases code for 20 amino acids?
The Math Behind the Code
- If each base coded for one amino acid, only four amino acids could be specified.
- If two bases were used per amino acid, there would be $4^2 = 16$ combinations, still not enough.
- Using three bases per amino acid provides $4^3 = 64$ combinations, more than enough to cover all 20 amino acids.
Valine is coded by GUU, GUC, GUA, and GUG.
NoteThis redundancy allows for extra codons, which are used for multiple purposes, such as start and stop signals in protein synthesis.
Why Is Degeneracy Important?
- Error Tolerance: Degeneracy helps protect against mutations.
