1. Chromosomal Mutations
When changes occur in the number or sequence of a chromosome.

2. Deletion
When a part of a chromosome is left out.

3. Insertion
When a part of a chromatid breaks off and attaches to its sister chromatid. The result is a duplication of genes on the same chromosome.

4. Inversion
When a part of a chromosome breaks off and reattaches backwards.

5. Translocation
When a part of one chromosome breaks off and is added to a different chromosome.

6. Duplication
Appears to repeat a portion of chromosome on the same chromosome. Increases the amount of genetic material.

7. Nondisjunction
The failure of one or more pairs of homologous chromosomes or sister chromatids to separate normally during nuclear division, usually resulting in an abnormal distribution of chromosomes in the daughter nuclei.

8. Monosomy
Missing a copy of the chromosome.

9. Trisomy
Extra copy of a chromosome.