Glossary

allele       (uh-LEEL)
An alternative form of a gene.

autosome       (AW-tuh-some)
A chromosome that is not directly involved in determining sex, as opposed to the sex chromosomes.

chi square test
A commonly used statistical method to determine the goodness of fit.

dihybrid cross       (DY-HY-brid)
A breeding experiment in which parental varieties differing in two traits are mated.

diploid cell       (DIP-loyd)
A cell containing two sets of chromosomes (2n), one set inherited from each parent.

dominant allele
In a heterozygote, the allele that is fully expressed in the phenotype.

F1 generation
The first filial or hybrid offspring in a genetic cross-fertilization.

F2 generation
Offspring resulting from interbreeding of the hybrid F1 generation.

gamete       (GAM-eet)
A haploid egg or sperm cell; gametes unite during sexual reproduction to produce a diploid zygote.

genetics
The branch of biology concerned with the study of heredity and variation.

genotype       (JEE-noh-type)
The genetic makeup of an organism.

haploid cell       (HAP-loid)
A cell containing only one set of chromosomes (n).

homologous chromosomes       (home-OL-uh-gus)
Chromosome pairs of the same length, centromere position, and staining pattern that possess genes for the same traits at corresponding loci. One homologous chromosome is inherited from the organismıs father, the other from the mother.

homozygous       (HOME-oh-ZY-gus)
Having two identical alleles for a given trait.

heterozygous       (HET-ur-oh-ZY-gus)
Having two different alleles for a given trait.

law of independent assortment
Mendelıs second law, stating that each allele pair segregates independently during gamete formation; applies when genes for two traits are located on different pairs of homologous chromosomes.

law of segregation
Mendelıs first law, stating that allele pairs separate during gamete formation, and then randomly re-form pairs during the fusion of gametes at fertilization.

locus       (LOH-kus) (plural, loci)
A particular place along the length of a certain chromosome where a given gene is located.

monohybrid cross
A breeding experiment that uses parental varieties differing in a single character.

P generation
The parental generation in a genetic cross.

phenotype       (FEE-nuh-type)
The physical and physiological traits of an organism.

recessive allele
In a heterozygote, the allele that is completely masked in the phenotype.

sex chromosomes
The pair of chromosomes responsible for determining the sex of an individual.

somatic cell       (soh-MAT-ik)
Any cell in a multicellular organism except a sperm or egg cell.

wild type
An individual with the normal phenotype.