DNA fragments obtained by restrictions enzyme digestion and separation on gel can be transferred from the gel by blotting to Nitrocellulose or nylon membrane that binds the DNA,The DNA bound to the membrane is denatured and treated with radioactive single stranded segment, which can be detected on x-ray film.This highly sensitive technique for identifying DNA fragments by DNA-DNA hybridization is called southern blotting,afte6EM southern who devised it.This techniques has very wide application in DNA analysis.An analogous procedure for the analysis of RNA has been called northern blotting.Here the RNA mixture is separated by gel electrophoresis,blotted and identified using labelled DNA or RNA probes.
A similar techniques for the identification of protein is called immunoblottinh . Here the protein antigen mixture is separated by SDS-PAGE, blotting on to Nitrocellulose strips and identified by radiolabeled or enzyme labeled antibodies as probes.The western blot test has received wide publicity as the confirmatory test for the diagnosis of HIV antibody in sera.The specificity of the diagnosis of HIV antibody in sera.The specificity of the test depends on its ability to seperately identify antibodies directed against different antigens of the pathogen .
Molecular epidemiology:One offshoot of molecular genetics is molecular epidemiology.Here molecular method such as plasmids profile analysis,genomic finger printing and PCR are used for the identification and matching of microbial isolates for epidemiological purpose.
Genetics mapping:As a result of the remarkable advance in molecular genetics,it has been possible to delineate the complete genomic sequence of bacteriophage and other viruses,bacteria and plasmids, and even of some eukaryotic including mammals.Quite apart from the useful information it has provided in microbiology,it's succes emboldened the international scientific community to venture on the human genome project,the most expensive and ambitious scientific project thus far undertaken in biology.The results of this mammoth study became available at the beginning of the twenty first century and have opened vistas in human biology and medicine,as well as controversies and dilemmas that transcend medicine.The total genetics constitution of an organism is its genotype.The genotype represent the sum total of the potential an organism possesses if all its genes are expressed.The genotype of a cell is determined by the genetic information contained in its entire DNA content or genome, carried on the chromosome or plasmids.thank you all for your time thank you.
