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strand 8 genetic fingerprinting - Coggle Diagram
strand 8 genetic fingerprinting
within these introns short sequences of bases are repeated several times
these are known as variable number tandem repeats (VNTRs) eg AGTAGTAGTAGT
for every individual the number and length of VNTRs has a unique pattern
the number of times each VNTR is repeated is inherited from parents in the same way genes are
additional info
95% of human DNA is currently not known to code for any characteristic but may yet be found to be functional
non coding bases of DNA are known as variable number tandem repeats (VNTRs). for every individual the number and length of VNTRs have a unique pattern
technique relies on the fact that the genome of most eukaryotic organisms contain many repetitive non coding bases of DNA
the more closely related two individuals are the more the similar the VNTRs will be
uses of genetic fingerprinting
forensic science
medical diagnosis
genetic relationships and variability
plant and animal breeding
method
the fragments of DNA are next separated according to size by gel electrophoresis under the influence of an electrical voltage. the gel is then immersed in alkali in order to separate the double strands into single strands
radioactive (or fluorescent) DNA probes are now used to bind with VNTRs. the probes have base sequences of the VNTRs, and bind to them under specific conditions, such as temperature and pH. the process is carried out, with different probes which bind to different target DNA sequences
the DNA is then cut into fragments, using the same restriction endonucleases. the endonucleases are chosen for their ability to cut close to, but not within, the target DNA
extraction - even the tiniest sample of animal tissue, such as a drop of blood or a hair root, is enough to give a genetic fingerprint. Whatever the sample, the first stage is to extract the DNA by separating it from the rest of the cell. As the amount of DNA is usually small, its quantity can be increased by using the polymerase chain reaction
finally, an X ray film is put over the nylon membrane. the film is exposed by the radiation from the radioactive probes. (if using fluorescent probes, the positions are located visually) because these points correspond to the position of the DNA fragments as separated, during electrophoresis a series of bars is revealed. the pattern of the bands is unique to every individual except identical twins