Introduction of applied genetics
Early in human history, people unwittingly began the process of manipulating the
genetic constitutions of organisms by their selection of plants and animals in the new
activity of agriculture .The breeding of domesticated species of plants and animals
involves artificial selection and natural hybridization between related species and the
doubling of whole sets of chromosomes to give polyploids.
In artificial selection, genetic modification is brought about when organisms with
favorable characteristics that are genetically controlled are permitted to breed , and
the progeny they produce are similarly sorted .Those with favorable characteristics are
used as further breeding stock, and so of . Meanwhile, progeny without favored
characteristics are excluded from breeding. The result is a shift in the genotypes of
new individuals away from those of the original pop ulation, and consequently a
change in the gene pool. A sample of the gene pool forms the genomes (gene sets of
individuals) of the next generation. The plants and animals of our farms and gardens
and homes are all generation. The plants and animals of our farms and gardens and
homes are all genetically modified by these processes.
Today a new type of genetic manipulation is in use, known as genetic engineering of
recombinant DNA technology. The extremely long double strands of DNA found in
the nucleus are function alls divided into shorter lengths, the genes. In recombinant
DNA technology, genes from one organism are introduced into the genome of an
unrelated organism. One outcome has been the ‘engineering’ of new varieties of
organism, mostly microorganisms, which are used in the manufacture of useful
chemicals by biotechnological processes, The work also extends our knowledge of the
functioning gene ,another aspect of the pure research we call molecular biology .