Glossary
- allele - (contraction of allelomorph) One of two or more alternative forms of a gene. The product of the mutation of a gene.
- chromosome - a long strand of DNA and associated proteins which carries the hereditary information of a species. Depending on the species, a cell nucleus may contain from two to hundreds of chromosomes. Humans have 46 chromosomes in two sets of 23 (2n=46), goldfish more than twice that number.
- diploid - having two sets of chromosomes.
- epistasis - the masking of the effects of a gene by one at a different locus.
- gamete - a single male or female reproductive cell having half the number of chromosomes found in a normal cell. Two gametes of opposite sex combine to form a zygote.
- gene - a sequence of DNA which occurs at a specific locus on a chromosome, and which controls a specific inherited characteristic.
- haploid - having a single set of chromosomes. The haploid number in humans is 23, of sweet peas 7.
- heterozygous - having different alleles of a particular gene.
- homozygous - having identical alleles at the equivalent loci on each of a pair of chromosomes.
- locus - the position on a chromosome where a specific gene resides.
- mutation - the spontaneous alteration of the DNA sequence in a gene. Most mutations are from the dominant form of a gene to its recessive. A mutation from recessive to dominant is called a reversion.
- zygote - the cell formed by the fusion of male and female gametes. The starting point of a new individual.