Genetics: Analysis of Genes and Genomes: Keyword Hot Links for chapter 14

DNA elements that could undergo transposition from one site in the genome to another were originally discovered by Barbara McClintock in maize. Her experiments began by studying a mutation in the colored (C) gene in chromosome 9, which is necessary for synthesis of a purple anthocyanin deposited in the outer layer of corn seed. The mutation was caused by the insertion of a transposable element (Ds) that could not transpose on its own but that could transposase in the presence of an "active" element (Ac). In genetic backgrounds carrying Ac, McClintock observed frequent excision of Ds from its insertion site in C, restoring the color in the cell lineage and resulting in mottled kernels. Visit this keyword site for a visualization of this process at the molecular and cellular level.

Some inherited defects in DNA repair are expressed early in life. These include ataxia-telangiectasia, Bloom syndrome, Fanconi anemia, and xeroderma pigmentosum. The incidence and genetic basis of each of these conditions, along with their symptoms and other manifestations, as well as possibilities for treatment, can be found in this database of over 550 childhood illnesses.

The Chernobyl (also spelled Chornobyl) nuclear accident was by far the most devastating in the history of nuclear power. It released into the Earth's atmosphere about 400 times more radioactive material than the atomic bomb dropped on Hiroshima, but less than 1 percent of the amount from atmospheric weapons tests conducted in the 1950s and 1960s. This keyword site summarizes what is known about the nuclear accident and its aftermath—what happened, how it happened, how many people were seriously exposed to radiation, the immediate health effects, and the anticipated long-term health and environmental effects of this environmental disaster.