Unit 5 AP Biology vocab terms

Allele

A variant form of a gene that is located at a specific position on a specific chromosome.

Aneuploid

An organism with an abnormal number of chromosomes, not an exact multiple of the haploid number.

Autosome

Any chromosome that is not a sex chromosome, typically found in pairs in diploid organisms.

Chromosome map

A diagram that shows the relative positions of genes on a chromosome.

Crossing over

The exchange of genetic material between homologous chromosomes during meiosis.

Diploid

A cell or organism that has two sets of chromosomes, one from each parent.

Dominant

An allele that is expressed in the phenotype even in the presence of a recessive allele.

Euploid

An organism or cell with a complete set of chromosomes, typically a multiple of the haploid number.

Gamete

A reproductive cell (sperm or egg) that contains half the genetic material of an organism.

Genotype

The genetic constitution of an organism, represented by its alleles.

Haploid

A cell or organism that has a single set of chromosomes.

Heterozygous

An individual with two different alleles for a particular gene.

Homologous chromosomes

Pairs of chromosomes that are similar in shape, size, and genetic content.

Homozygous

An individual with two identical alleles for a particular gene.

Independent assortment

The random distribution of alleles during gamete formation.

Linked genes

Genes that are located on the same chromosome and tend to be inherited together.

Monosomy

The condition of having one less than the diploid number of chromosomes.

Nondisjunction

The failure of homologous chromosomes or sister chromatids to separate properly during meiosis.

Phenotype

The physical expression or characteristics of an organism's genotype.

Recessive

An allele that is masked by the presence of a dominant allele in the phenotype.

Recombinant chromosome

A chromosome created by the combination of genetic material through crossing over.

Recombination frequency

The frequency of recombination between two genes, used to determine their distance apart on a chromosome.

Sex chromosome

A chromosome that determines the sex of an individual, typically X or Y in humans.

Sex-linked trait

A trait associated with a gene located on a sex chromosome.

Somatic cell

Any cell of the body except for germ cells (sperm and egg).

Tetrad

A structure that forms during meiosis consisting of four chromatids, or two homologous chromosomes.

Trisomy

The condition of having an extra chromosome, resulting in three copies of a particular chromosome.

Zygote

The fertilized ovum, the result of the union of a sperm and egg.

Phenotypic plasticity

The ability of an organism to change its phenotype in response to environmental conditions.