Intro to Genetics

Homozygous

An organism that has two identical alleles for a trait

Heterozygous

An organism that has two different alleles for a trait

Law of Dominance

recessive alleles will always be masked by dominant alleles

Law of Segretation

Mendel's law that states that the pairs of homologous chromosomes separate in meiosis so that only one chromosome from each pair is present in each gamete

law of independent assortment

Each member of a pair of homologous chromosomes separates independently of the members of other pairs so the results are random

Genotype

genetic makeup of an organism

Phenotype

An organism's physical appearance, or visible traits.

Alleles

Different forms of a gene

Mendel

studied pea plants; responsible of the Law of Inheritance

sickle cell anemia

a genetic disorder that causes abnormal hemoglobin, resulting in some red blood cells assuming an abnormal sickle shape

cystic fibrosis

A genetic disorder that is present at birth and affects both the respiratory and digestive systems.

Phenylkeonuria (PKU)

autosomal recessive disorder; cannot breakdown the amino acid phenylalanine

sex-linked traits

Traits controlled by genes located on sex chromosomes.

color blindness

A sex-linked trait in which an individual cannot perceive certain colors.

Hemophilia

An X-linked recessive disorder in which blood fails to clot properly

Codominance

A condition in which both alleles for a gene are fully expressed

incomplete dominance

Situation in which one allele is not completely dominant over another allele

Pedigree

A chart or "family tree" that tracks which members of a family have a particular trait

autosomal recessive

two copies of an abnormal gene must be present in order for the disease or trait to develop

Huntington's disease

A human genetic disease caused by a dominant allele; degeneration of the nervous system; usually fatal 10 to 20 years after the onset of symptoms.