- These are unpredictable changes in the genetic makeup of a cell, involving either the sequence of particular bases at one location (gene mutation) or changes to the whole chromosome (chromosomal mutation).
- Mutation usually happens when gametes are formed or during division of body cells (somatic cells).
- The body of an organism tends to have its own DNA repair system. Enzymes cut and repair any part of the DNA strand that has become broken or damaged.
- Point Mutation
- Involves miscopying of one or small number of nucleotides. This translates to a change in the protein made.
- Part of a chromosome breaks off and is lost
- Part of the chromosome breaks off and rejoins the other way round
- Part of a chromosome breaks and rejoins another chromosome.
- Part of a chromosome becomes repeated
Whole chromosome mutation
- Entire chromosome is either lost during meiosis or duplicated in one cell by errors in the process
- Example: Dawn syndrome where extra chromosome 21 i.e. three instead of two. The two chromatids of chromosome 21 fail to separate and both go into the daughter cells.
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