Genetics Vocabulary Definitions

A comprehensive vocabulary review of terms related to DNA replication, RNA transcription, translation, protein synthesis, and genetic mutations.

Genome

An organism's complete set of genetic instructions.

Karyotype

A display of the chromosome pairs of a cell arranged by size and shape; picture of the chromosomes

Pedigree

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

Allele

One of the alternative forms of a gene that governs a characteristic.

Autosome

Chromosome that is not a sex chromosome.

Sex chromosome

The X and the Y

Test-cross

Testing a suspected heterozygote by crossing it with a known homozygous recessive.

Codominance

Situation in which both alleles of a gene are expressed and contribute to the phenotype of the

organism

Dihybrid cross

Cross involving two traits

Dominant trait

An allele that produces the same phenotype whether its paired allele is homozygous or

heterozygous.

Recessive trait

An allele that is expressed only when its paired allele is also recessive.

Probability

The likelihood that a particular event will occur.

X-linked trait

Inheritance controlled by a gene on the X chromosome.

Gene

A segment of DNA on a chromosome that codes for a specific trait.

Genetics

The study of patterns of inheritance

Genotype

The alleles at specified loci present in an organism.

Phenotype

Physical expression of a trait.

Heterozygous

Having two different alleles for a trait.

Homozygous

Having two identical alleles for a trait.

Hybrid

An organism that is heterozygous for a particular trait.

Incomplete Dominance

One allele is not completely dominant over the other allele and a 3rd phenotype is expressed

Independent Assortment

Principle that genes do not influence each other's inheritance because they are separated

independently during meiosis.

Gene Linkage

Genes located on the same chromosome that tend to be inherited together in genetic crosses.

Multiple alleles

Three or more alleles of a gene available that code for a single trait.

Law of Segregation

The separation of paired alleles during meiosis so that members of each pair of alleles appear

in different gametes.

Trait

A characteristic that an organism can pass on to its offspring through its genes.

Polygenic traits

Traits controlled by two or more genes

Purebred

An organism that always produces offspring with the same form of a trait as the parent.