genetic code

• Mutations - errors may occur and the wrong nucleotide may be inserted. This could change the genetic code, called point mutation.

  Not all mutations are harmful, some can be advantageous. During the replication process there are enzymes that can proofread and edit out incorrect nucleotides, reducing the rate that mutations are produced.
• The genetic code is near universal, in almost all living organisms the same triplet of DNA bases codes for the same amino acid.
• The genetic code is degenerate, for all amino acids (except methionine and tryptophan) there is more than one base triplet. This may reduce the effect of point mutations, as a change in one base of the triplet could produce another base triplet that still codes for the same amino acid.
• The genetic code is non-overlapping, it is read starting from a fixed point in groups of three bases. If a base is added or deleted then it causes a frame shift, as every base triplet after that, and hence every amino acid coded for, is changed