A random mutation means that there is a change in the base sequence of DNA. This could result in a different codon (sequence of 3 bases) and this means a different amino acid could be coded for. This means that the protein made from the different amino acids could be different.
There is three main effects of a random mutation and these are:
- Damaging - if a different amino acid is coded for, a different protein could be made with a different active site so it can no longer fit the substrate so cannot perform its function (for example, amylase changes active site shape so can no longer break down starch)
- No effect - many amino acids are 'degenerate' - This means that the same amino acid can be coded for by different codons. This means a change in the base sequence due to 'random mutation' can still lead to the same amino acid being made so there is no effect on the protein made
- Beneficial - e.g. a change in amino acid coded for could result in a better fit of substrate into the active site of an enzyme
Hope this helps!