Chapter 12 - Vocabulary

Genetics

Scientific study of heredity.

Fertilization

Process in sexual reproduction in which male and female reproductive cells join to form a new cell.

Trait

Scientific characteristic of an individual.

Hybrid

Offspring of crosses between parents with different traits.

Gene

Sequence of DNA that codes for a protein and thus determines a trait; factor that is passed from parents to offspring.

Allele

One number of different forms of a gene.

Principle of dominance

Mendel's second conclusion, which states that some alleles are dominant and others are recessive.

Segregation

Separation of alleles during gamete formation.

Gamete

Sex cell.

Probability

Likelihood that a particular event will occur.

Homozygous

Having two identical alleles for a particular gene.

Heterozygous

Having two different alleles for a particular gene.

Phenotype

Physical characteristics of an organism.

Genotype

Genetic makeup of an organism.

Punnett square

Diagram that can be used to predict the genotype and phenotype combinations of a genetic cross.

Independent assortment

One of Mendel’s principles that states that genes for different traits can segregate independently during the formation of gametes.

Incomplete dominance

Situation in which one allele is not completely dominant over another allele.

Codominance

Situation in which the phenotypes produced by both alleles are completely expressed.

Multiple alleles

A gene that has more than two alleles.

Polygenic trait

Trait controlled by two or more genes.

Homologous

Term used to refer to chromosomes in which one set comes from the male parent and one set comes from the female parent.

Diploid

Term used to refer to a cell that contains two sets of homologous chromosomes.

Haploid

Term used to refer to a cell that contains only a single set of genes.

Meiosis

Process in which the number of chromosomes per cell is cut in half through the separation of homologous chromosomes in a diploid cell.

Tetrad

Structure containing four chromatids that forms during meiosis.

Crossing-over

Process in which homologous chromosomes exchange portions of their chromatids during meiosis.