amphidiploid An allopolyploid; a polyploid formed from the union of two separate chromosome sets and their subsequent doubling. An organism produced by hybridization of two species followed by chromosome doubling. An allotetraploid that appears to be a normal diploid amplification of DNa The production of many DNA copies from one or a few copies anagenesis The evolutionary process whereby one species evolves into another without any splitting of the phylogenetic tree. See cladogenesis anaphase The stage of meiosis and mitosis in which sister chromatids(meiosisll) or homologous chromosomes(mitosis and meiosis) are separated by spindle fibers. An intermediate stage of nuclear division during which chromosomes or chromatids are pulled to the poles of the spindle aneuploid cell A cell having a chromosome number that differs from the normal chromosome number for the species by a small number of chromosomes aneuploid Individuals or cells exhibiting aneuploidy aneuploidy The condition of a cell or of an organism that has additions or deletions of a small number of whole chromosomes from the expected balanced diploid number of chromosomes angiosperm Plant whose seeds are enclosed within an ovary. Flowering plants animal breeding The practical application of genetic analysis for development of lines of domestic animals suited to human purposes annealing Spontaneous alignment of two complementary polynucleotide(RNA, or DNA,or RNA and dna)strands to form a double helix antI-oncogene a gene that prevents malignant ( cancerous) growth and whose absence, by mutationamphidiploid An allopolyploid; a polyploid formed from the union of two separate chromosome sets and their subsequent doubling. An organism produced by hybridization of two species followed by chromosome doubling. An allotetraploid that appears to be a normal diploid. amplification of DNA The production of many DNA copies from one or a few copies. anagenesis The evolutionary process whereby one species evolves into another without any splitting of the phylogenetic tree. See cladogenesis. anaphase The stage of meiosis and mitosis in which sister chromatids (meiosisII) or homologous chromosomes (mitosis and meiosisI) are separated by spindle fibers. An intermediate stage of nuclear division during which chromosomes or chromatids are pulled to the poles of the spindle. aneuploid cell A cell having a chromosome number that differs from the normal chromosome number for the species by a small number of chromosomes. aneuploid Individuals or cells exhibiting aneuploidy. aneuploidy The condition of a cell or of an organism that has additions or deletions of a small number of whole chromosomes from the expected balanced diploid number of chromosomes. angiosperm Plant whose seeds are enclosed within an ovary. Flowering plants. animal breeding The practical application of genetic analysis for development of lines of domestic animals suited to human purposes. annealing Spontaneous alignment of two complementary single polynucleotide (RNA, or DNA, or RNA and DNA) strands to form a double helix. anti-oncogene A gene that prevents malignant (cancerous) growth and whose absence, by mutation, results in malignancy (eg retinoblastoma)