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In this chapter of AS/A-Level Biology, we will learn about different types of mutation and their effects.
Mutation
- 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.
Chromosomal Mutation
- Point Mutation
- Involves miscopying of one or small number of nucleotides. This translates to a change in the protein made.
- Deletion
- Part of a chromosome breaks off and is lost
- Inversion
- Part of the chromosome breaks off and rejoins the other way round
- Translation
- Part of a chromosome breaks and rejoins another chromosome.
- Duplication
- 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.
This is the end of this topic
