Unit 8

Gene

A chunk of DNA that codes for a particular trait

Heterozygous

Having two different alleles

Homozygous

Having two of the same alleles

Diabetes

A disease where a person has a problem with the hormone insulin

Pedigree

A family tree of genetic traits

Allele

A letter in the genotype, one of two or more alternative forms of a gene.

Karyotype

A picture of a person's chromosomes that doctors can use to diagnose some genetic disorders and see the gender of the offspring. It shows extra, missing, and damaged chromosomes

Independent Assortment

An event in Metaphase I of Meiosis I in which chromosomes are sorted randomly, thus, adding to the genetic variations created during crossing over

Crossing Over

An event in Prophase I of Meiosis I in which chromosomes hug, break apart, and exchange genetic material. This increases variation in each gamete. All of the gametes in an organism will continue the same DNA, yet in different combinations

Sex-linked inheritance

An inheritance pattern that is on the X chromosome

Co-dominant inheritance

An inheritance pattern where two traits are expressed equally

Incomplete dominance inheritance

An inheritance pattern where two traits blend to form a new phenotype

Meiosis

Cell division that creates 4 haploid gametes (sperm and egg) with 23 chromosomes in humans

Mitosis

Cell division that creates body cells with 46 chromosomes in humans. The process is necessary for growth and repair in organisms

Nondisjunction

Failure of chromosomes to separate properly during meiosis I, resulting in gametes with additional or insufficient numbers or chromosomes

Genetic Variation

Differences that occur between parent and offspring

Phenotype

Observable characteristics/traits

PKU

Phenylketonuria, a recessive genetic disorder where a person can not process the amino acid phenylalanine

Expression

The appearance of a phenotype of a particular gene

Genotype

The genetic makeup of a cell

Genetic Trait

The individual's phenotype or observable traits