During reproduction germ cells from one organism (in asexual reproduction) or two organisms (in sexual reproduction) combine to form a fertilized egg which will grow into a new organism.
several ways errors can creep into the construction of a germ cell. When
these errors occur, a mutation is introduced, and the new individual will
be different from either of its parents. Genes are basically just long
strands of DNA, which can be thought of as strings formed from an
alphabet of four characters (A, C, G and T).
Examples of the kinds of errors that can occur are random insertions
(e.g. the string should be
ATTA but instead comes out
ATTA is copied as
ATA), and substitution
errors, where a different letter is used (e.g.
ATGA instead of