2.2.3-2.2.6 PBS Vocab

Genotype

An organism's genetic makeup, or allele combinations.

Phenotype

An organism's physical appearance, or visible traits.

Alleles

alternative versions of a gene

dominant allele

An allele whose trait always shows up in the organism when the allele is present.

recessive allele

An allele that is masked when a dominant allele is present

Homozygous

An organism that has two identical alleles for a trait (HH/hh)

heterozygous

An organism that has two different alleles for a trait, one dominant and one recessive (Hh)

Gametes

reproductive cells; egg or sperm

Pedigree

A diagram that shows the occurrence of a genetic trait in several generations of a family.

autosome

Any chromosome that is not a sex chromosome

sex chromosomes

X and Y chromosomes.

autosomal dominant

inheritance pattern of a dominant allele on an autosome; like NF1 or FH

autosomal recessive

two copies of an abnormal gene must be present in order for the disease or trait to develop; like sickle cell anemia

Punnett Square

A chart that shows all the possible combinations of alleles that can result from a genetic cross

Karyotype

A display of the chromosome pairs of a cell arranged by size and shape.

Meiosis

Cell division that produces reproductive cells in sexually reproducing organisms

meiosis 1

Homologous chromosomes separate

meiosis 2

sister chromatids separate

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 and a child with monosomy or trisomy

gel electrophresis

procedure used to separate and analyze DNA fragments by placing a mixture of DNA fragments at one end of a porous gel and applying an electrical voltage to the gel