Genetic single base exchange

It is worth looking at the various base sequences with the help of the genetic code. All the pairs of codon units which are linked by arrows in Table 8.2 differ by only one single base exchange. 

Allele One form of a genetic locus, distinguished from other forms (= alleles) by its particular nucleotide or its coded amino acid sequence. Single nucleotide polymorphisms are biallelic, i.e., one base pair is exchanged with just one other base pair. In such a case, only two different alleles exist in the population for such a gene locus. However, several different alleles may exist in the population if the locus is defined by more than one nucleotide (i.e., microsatelhtes, haplotypes). Thus,... 

Maple syrup urine disease is a rare genetic disorder affecting the metabohsm of leucine, isoleucine and valine. Accumulation of these branched-chain amino acids results in severe neurological damage and death. The aim of dietary management is to prevent the accumulation of these amino acids, by the use of a low-protein diet and leucine-, isoleucine-and vahne-free amino acid preparations. Natural protein supplies the necessary leucine, isoleucine and valine, based on a leucine exchange system with additional isoleucine and/ or valine available as single amino acid supplements. 

The most easily tolerated mutations are point mutations, in which a single nucleic acid base is exchanged. Since the genetic code is degenerate, both the... 

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