Amniotic fluid - liquid contents of the amniotic sac of higher vertebrates, containing cells of the embryo (not of the mother). Both fluid and cells are used for diagnosis of genetic abnormalities in the embryo or foetus

Amorph - a mutation that obliterates gene function

Amphidiploid - a species or type of plant derived from doubling the chromosomes in the F 1 hybrid of two species; an allopolyploid. In an amphidiploid the two species are known, whereas in other allopolyploids they may not be known

Amphimixis - true sexual reproduction involving the fusion of male and female gametes and the formation of a zygote

Ampicillin - a penicillin derived antibiotic that prevents bacterial growth by interfering with synthesis of the cell wall

Amplification - 1. treatment (e.g., use of chloramphenicol) designed to increase the proportion of plasmid DNA relative to that of bacterial (host) DNA
2. replication of a gene library in bulk
3. duplication of gene(s) within a chromosomal segment
4. creation of many copies of a segment of DNA by the polymerase chain reaction (PCR)

Amplify - to increase the number of copies of a DNA sequence, either in vivo by inserting into a cloning vector that replicate within a host cell, or in vitro by polymerase chain reaction (PCR)

Amylase - a group of enzymes that degrade starch, glycogen and other polysaccharides, producing a mixture of glucose and maltose. Plants have both a-and b-amylase; animal have only a-amylase

Amylolytic - the capability of breaking down starch into sugars

Amylopectin - a polysaccharide comprising highly branched chains of glucose molecules. The water insoluble portion of starch

Amylose - a polysaccharide consisting of linear chains of 100 to 1000 glucose molecules. The water soluble portion of starch

Anabolic Pathway - a pathway by which a metabolite is synthesised; a biosynthetic pathway

Anaerobe - an organism that can grow in the absence of oxygen. Opposite: aerobe

Anaerobic - an environment or condition in which molecular oxygen is not available for chemical, physical or biological processes

Anaerobic digestion - digestion of materials in the absence of oxygen. S ee anaerobic respiration

Anaerobic respiration - respiration in which food stuffs are partially oxidised, with the release of chemical energy, in a process not involving atmospheric oxygen, such as alcoholic fermentation, in which one of the end products is ethanol

Analogous - features of organisms or molecules that are superficially or functionally similar but have evolved in a different way or contain different compounds

Anaphase - the stage of mitosis or meiosis during which the daughter chromosomes (sister chromatids) pass from the equatorial plate to opposite poles of the cell (toward the ends of the spindle). Anaphase follows metaphase and precedes telophase

Anchor gene - a gene that has been positioned on both the physical map and the linkage map of a chromosome

Androgen - any hormone that stimulates the development of male secondary sexual characteristics, and contributes to the control of sexual activity in vertebrate animals. Usually synthesised by the testes

Androgenesis - male parthenogenesis, i.e., the development of a haploid embryo from a male nucleus. The maternal nucleus is eliminated or inactivated subsequent to fertilisation of the ovum, and the haploid individual (referred to as androgenetic) contains in its cells the genome of the male gamete only. Androgenesis is detected by cytological staining

Aneuploid - an organism or cell having a chromosome number that is not an exact multiple of the monoploid (x) with one chromosome being present in greater (e.g., trisomic 2n + 1) or lesser (e.g., monosomic 2n - 1) number than the normal diploid number

Animal cell immobilisation - entrapment of animal cells in some solid material in order to produce some natural product or genetically engineered protein. Animal cells have the advantage that they already produce many proteins of pharmacological interest, and that genetically engineered proteins are produced by them with the post-translation modifications normal to animals. However, because animal cells are much more fragile than bacterial ones, they cannot tolerate a commercial fermentation process. Typical materials are hollow fibre membrane bioreactors, or porous carriers made of polysaccharide, protein, plastic or ceramic materials with microscopic holes inside which the cells grow

Animal genome (gene) bank - a planned and managed repository containing animal genetic resources. Repositories include the environment in which the genetic resource has developed, or is now normally found ( in situ ) or facilities elsewhere ( ex situ in vivo or in vitro ). For in vitro, ex situ genome bank facilities, germplasm is stored in the form of one or more of the following: semen, ova, embryos and tissue samples

Anneal - the pairing of complementary DNA or RNA sequences, via hydrogen bonding, to form a double-stranded polynucleotide. Most often used to describe the binding of a short primer or probe