ABSTRACT
References ......................................................................................................................................193
Genomics has developed through many different stages since G. Mendel’s first insights into heredity. Early attempts at organizing the available information about the hereditary “units” were based on observations of abnormalities, deviations from the “regular,” i.e., most common, phenotypes, and their distribution and behavior within a population. Even today the majority of known human genes, for example, are linked to a particular disease. Genetic maps based on linkage analysis, recombination frequencies, and complementation analysis were among the first tools in genomics. Chromosomes (from Greek, meaning “colored bodies”) actually received their name because of specific characteristic staining; differential color banding was later used as a consistent marker and mapping tool. Physical maps that were initially based only on available physical markers followed. The pioneering Nobel work of G. Beadle and E. Tatum found the connection between genetic material and proteins. In Thomas Morgan’s complementation studies done with
Drosophila
flies, the “finest tool” for genome mapping detailed the early maps down to several centiMorgans (recombination units later calculated to be equal to about 1000 nucleotides). These and the award-winning work
of J. Lederberg in the field of bacterial genetic recombination are all cornerstones in the studies in genomics and are, in brief, a summary of the methods preceding the direct molecular level studies of the genetic material.
