Conservation genetics – molecular detectives at work
Glossary
allele. Genes can exist in more than one form. Each different form of the same gene is called an allele. For example, in the case of seed shape, there is one allele that determines wrinkled seeds and another allele that determines round seeds.
base. Any one of four nitrogenous (nitrogen-containing) bases (adenine, thymine, guanine and cytosine). The sequence of the bases in DNA determines the sequence of amino acids in all proteins found in living things.
complementary. Describes the specific matching of base pairs. This matching occurs because the structure of one base precisely fits with, and bonds to, another specific base. In DNA adenine and thymine are complementary and form a base pair, as do cytosine and guanine. When pairing occurs between DNA and RNA, adenine and uracil are complementary, and cytosine and guanine are complementary.
DNA (deoxyribonucleic acid). The nucleic acid forming the genetic material of all organisms with the exception of some viruses which have RNA. DNA is present in the nucleus and other organelles such as mitochondria and chloroplasts.
extinct. Occurring no more. The word is usually used for species but can apply to any level of classification. Recent extinctions are hard to prove, and an ‘official’ limit of 50 years with no recorded sightings of the species is now used.
enzyme. A protein that acts as a catalyst. Every chemical reaction in living organisms is facilitated by an enzyme.
gene. The basic unit of inheritance. A gene is a segment of DNA that specifies the structure of a protein or an RNA molecule.
genetic diversity. The variety of different types of genes or alleles in a species or population. Genetic diversity is really a form of biodiversity.
species. Living things of the same kind that are potentially capable of breeding and producing fertile offspring. Theoretically, plants or animals of different species cannot interbreed. However, occasionally this does not hold true.
Posted August 1999.