Genetics Bio

Gene

A piece of DNA that controls a trait.

Allele

A version of a gene (like tall or short).

Genotype

The genetic makeup (TT, Tt, or tt).

Phenotype

The physical traits you see.

Dominant

A trait that always shows up if present.

Recessive

A trait that is hidden by a dominant one.

Homozygous

Two of the same alleles (TT or tt).

Heterozygous

Two different alleles (Tt).

Gregor Mendel

The father of genetics.

Parental cross

A cross between two pure (homozygous) parents.

F1 generation

The first generation of offspring.

F2 generation

The second generation of offspring.

Law of independent assortment

Genes for different traits are inherited separately.

Incomplete dominance

Traits blend (red + white = pink).

Codominance

Both traits show up (black + white = speckled).

Multiple alleles

More than two allele options (like A, B, O for blood).

Polygenic trait

A trait controlled by more than one gene.(height and skin)

Sex-linked trait

A gene on the X or Y chromosome.

Punnett square

A chart to show possible offspring traits.

Pedigree

A chart that shows how traits are passed through a family.

Karyotype

A picture of all a person’s chromosomes.

Amniocentesis

A test that checks a baby’s genes before birth.

Type O

The universal donor blood type.

Type AB

The universal recipient blood type.

Type A

Blood type with A antigens and anti-B antibodies.

Type B

Blood type with B antigens and anti-A antibodies.

Universal donor

Blood type O.

Universal recipient

Blood type AB.

Dominant blood alleles

A and B.

Codominant blood alleles

A and B.

Total blood alleles

Three (A, B, O).

Total blood phenotypes

Four (A, B, AB, O).

Albinism

Lack of pigment in skin, hair, and eyes.

Cystic fibrosis

A disorder that affects lungs and digestion.

Color blindness

Can’t see certain colors (X-linked).

Duchenne muscular dystrophy

Muscle weakness (X-linked).

Hemophilia

Blood doesn't clot properly (X-linked).

Huntington’s disease

Brain cells break down; shows in adulthood (dominant).

PKU

Can’t break down a certain protein; can cause brain issues.

Sickle cell anemia

Red blood cells are sickle-shaped and carry less oxygen.