DNA Membrane

DNA Membrane

Introduction DNA, or Deoxyribonucleic acid, is a chemical structure that forms chromosomes which differentiate people’s individual traits. The structural build of a DNA molecule is a double helix which consists of two strands of genetic material spiraling around one another. The strands of DNA vary by having different orders of base pairs. There are millions of base pairs in each individual strand of DNA, so using these sequences would be time consuming. Instead, scientists use the repeating pattern found on DNA to determine whether two DNA samples are from the same person and of if the donors are related.

Exogenous DNA

Exogenous DNA refers to any deoxyribonucleic acid that originates outside of the organism of concern or study. The introduction of exogenous DNA into a cell is called transfection. This can take place naturally, as occurs when a virus infects cells, or artificially. Commonly used transfection methods are: (a) chemical methods, including calcium phosphate precipitation, DEAE-dextran complexation and lipid-mediated DNA transfer; (b) physical methods, including electroporation, microinjection, and biolistic particle delivery (gene gun); and (c) using recombinant, lab manipulated viruses as vectors.

Southern Blot Result

Hybridization of the probe to a specific DNA fragment on the filter membrane indicates that this fragment contains DNA sequence that is complementary to the probe. The transfer step of the DNA from the electrophoresis gel to a membrane permits easy binding of the labeled hybridization probe to the size-fractionated DNA. It also allows for the fixation of the target-probe hybrids, required for analysis by autoradiography or other detection methods. Southern blots performed with restriction enzyme-digested genomic DNA may be used to determine the number of sequences (e.g., gene copies) in a genome.