1. Types of mutations Mutations are changes in the genetic material
There are two basic types of mutations:
Gene mutations - mutations that produce changes in a single gene
Chromosomal mutations - mutations that produce changes in whole chromosomes

2. Gene mutations Point mutations:
Involves changes in one or a few nucleotides (they occur at a single point in the DNA sequence)
They can be:
Substitutions
Insertions
Deletions

3. Substitutions One base is changed to another
Substitutions usually only affect a single amino acid

4. Insertions and Deletions
A base is either inserted or removed from the DNA sequence
If a nucleotide is added or deleted, the bases are still read in groups of three, so every codon after is changed
These types of mutations cause Frameshift mutations
Can cause major changes to the protein, to the point where it can’t perform its normal function

5. Chromosomal mutations
Involve the chromosomal changes in the number or structure of chromosomes
Can change the locations of genes on chromosomes, and the number of copies of some genes
Four types:
Deletions
Duplications
Inversions
Translocations

6. Duplications and Deletion
Duplication (Nondisjunction):
The failure of a chromosome to separate from its homologue during meiosis
One gamete receives an extra copy of a chromosome and the other lacks it
Deletion:
Loss of a piece of a chromosome

7. Translocations and Inversions
When a chromosome piece breaks off and reattaches to another, nonhomologous chromosome
Inversion:
Chromosome segment breaks off and then reattaches in reverse orientation to the same chromosome

8. Significance of Mutations
Most mutations are neutral (they have little or no effect)
Mutations that cause dramatic changes in protein structure or gene activity can be very harmful
Mutations are a source of genetic variability in a species
Polyploidy- a mutation where an organism has an extra set of chromosomes
Polyploid plants are often larger and stronger