Nondisjunction- A chromosomal mutation that produces an offspring with an incorrect number of chromosomes.

Recessive Genes- A gene that is phenotypically expressed in the homozygous state but has its expression masked in the presence of a dominant gene.

Dominant Genes- A gene that is expressed phenotypically in heterozygous or homozygous individuals.

Somatic Cell- A somatic cell is any cell that makes up an organism, except for a reproductive cell. The cells that make up your skin are all somatic cells.

Germ Cell- a cell containing half the number of chromosomes of a somatic cell and able to unite with one from the opposite sex to form a new individual; a gamete.

Kleinfetter's syndrome- Klinefelter syndrome is a chromosomal condition that affects male physical and cognitive development. Klinefelter syndrome usually occurs randomly. An older mother might increase the risk slightly. The condition is not inherited from one's parents. The underlying mechanisms involves at least one extra X chromosome in addition to a Y chromosome such that there is a total of 47 or more chromosomes rather than the usual 46. Kleinfelter's Disease is neither Dominant or Recessive.

Down Syndrome- Down syndrome is a chromosomal condition that is associated with intellectual disability, a characteristic facial appearance, and weak muscle tone in infancy. Down Syndrome is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21. Down Syndrome can be Recessive or Dominant.

Colorblindness- Colorblindness is the decreased ability to see color or differences in color. Males are more likely to be color blind than females, as the genes responsible for the most common forms of color blindness are on the X chromosome. Red-green color blindness is a sex linked recessive trait and blue-yellow color blindness is a autosomal dominant trait.

Turner's Disease- Turner's Disease is a condition in which a female is partly or completely missing an X chromosome. Turner syndrome is not usually inherited from a person's parents. Turner syndrome is due to a chromosomal abnormality in which all or part of one of the X chromosomes is missing or altered. Turner's Disease is neither a Recessive or Dominant trait.