Unit 5: Hereditary (copy)

Diploid

A cell that has two sets of chromosomes, represented as '2n.'

Haploid

A cell that has one set of chromosomes, represented as 'n.'

Homologous chromosomes

The duplicate versions of each chromosome that are similar in size, shape, and contain the same genes in the same locations.

Gametes

Sex cells that are haploid and combine during fertilization to form a diploid zygote.

Locus

The position of a gene on a chromosome.

Homozygous

An organism with two identical alleles for a given trait.

Heterozygous

An organism with two different alleles for a given trait.

Phenotype

The physical appearance of an organism resulting from its genotype.

Genotype

The genetic makeup of an organism, specifically the alleles it possesses.

Dominant allele

An allele that masks the effects of a recessive allele and is represented by a capital letter.

Recessive allele

An allele that is masked by a dominant allele and is represented by a lowercase letter.

Monohybrid cross

A genetic cross that focuses on one trait and involves two individuals.

Dihybrid cross

A genetic cross that studies how two genes are passed on to offspring.

Law of Dominance

One trait masks the effects of another trait.

Law of Segregation

Each gamete receives only one copy of each gene.

Law of Independent Assortment

Each pair of homologous chromosomes splits independently, allowing for genetic variation.

Barr body

A condensed and inactive X chromosome in females.

Incomplete dominance

A genetic situation wherein neither allele is dominant over the other, resulting in a blending of traits.

Codominance

A genetic situation where both alleles are equally expressed, such as in AB blood type.

Non-nuclear inheritance

Genetic material inherited from mitochondria, which is passed through the maternal line.

Pedigree

A family tree that shows the inheritance patterns of specific traits over generations.

Nondisjunction

An error during meiosis where chromosomes fail to separate properly, leading to an abnormal number of chromosomes.

Down syndrome

A genetic condition caused by the presence of three copies of the 21st chromosome.

Gametogenesis

The process of meiosis that results in the formation of gametes.