Science / Genetics Glossary

Amplification: An increase in the number of copies of a specific dna fragment: can be in vivo or in vitro.

Aneuploidy: State of having variant chromosome number (too many or too few). (i.e. Down syndrome, turner syndrome).

Angelman Syndrome: A condition characterized by severe mental deficiency, developmental delay and growth deficiency, puppet-like gait and frequent laughter unconnected to emotions of happiness.

Anticipation: Each generation of offspring has increased severity of a genetic disorder: e.g., a grandchild may have earlier onset and more severe symptoms than the parent, who had earlier onset than the . . . View Full Definition

Antisense: Nucleic acid that has a sequence exactly opposite to an mrna molecule made by the body: binds to the mrna molecule to prevent a protein from being made.

Apert Syndrome: A condition caused by the premature closure of the sutures of the skull bones, resulting in an altered head shape, with webbed fingers and toes. Autosomal dominant.

Apoptosis: Programmed cell death, the body's normal method of disposing of damaged, unwanted, or unneeded cells.

Arrayed Library: Individual primary recombinant clones (hosted in phage, cosmid, yac, or other vector) that are placed in two-dimensional arrays in microtiter dishes. Each primary clone can be identified by . . . View Full Definition

Artificial Insemination: The placement of sperm into a female reproductive tract or the mixing of male and female gametes by other than natural means.

Assembly: Putting sequenced fragments of dna into their correct chromosomal positions.

Autoradiography: A technique that uses x-ray film to visualize radioactively labeled molecules or fragments of molecules: used in analyzing length and number of dna fragments after they are separated by gel . . . View Full Definition

Autosomal Dominant: A gene on one of the non-sex chromosomes that is always expressed, even if only one copy is present. The chance of passing the gene to offspring is 50% for each pregnancy.

Autosome: A chromosome not involved in sex determination. The diploid human genome consists of 46 chromosomes, 22 pairs of autosomes, and 1 pair of sex chromosomes (the x and y chromosomes).

Avuncular Relationship: The genetic relationship between nieces and nephews and their aunts and uncles.

Backcross: A cross between an animal that is heterozygous for alleles obtained from two parental strains and a second animal from one of those parental strains. Also used to describe the breeding proto . . . View Full Definition

Bacterial Artificial Chromosome (BAC): A vector used to clone dna fragments (100- to 300-kb insert size: average, 150 kb) in escherichia coli cells. Based on naturally occurring f-factor plasmid found in the bacterium e. Coli.

Bacteriophage: A virus whose host is a bacterium: commonly called phage.

Barr Body: The condensed single x-chromosome seen in the nuclei of somatic cells of female mammals. Base pair a pair of hydrogen-bonded nitrogenous bases (one purine and one pyrimidine) that join the c . . . View Full Definition

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