Info about Dna

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DNA Techniques

The development of methods using species-specific DNA fragments amplified by polymerase chain reaction (PCR) may be successfully applied to detect some cases of sophisticated types of adulteration, even on heavily processed foods. Nucleic acids are thermostable molecules in comparison with the thermosensitive protein molecules so that tests based on them


ADULTERATIONS OF FOODS/Detection 53 are much more sensitive than the conventional ELISA tests. Still, due to specialized training requirements, expensive equipment, and access demands to DNA sequence databases, the techniques are not used routinely unless there is no other method adequate to solve the problem.


Following the DNA changes, treatments that induce DNA fragmentation can be identified.


To determine the cultivar, the restriction-fragment length polymorphism (RFLP) concept is applied. Restriction enzymes are used to cut the strands of DNA at specific points where a specific sequence of nucleotides is recognized. The fragments separated by microelectrophoresis are stained or characterized using specific radioactive gene probes. The presence of common wheat in durum wheat is based on a specific DNA sequence on the D-genome, a set of chromosomes found only in common wheat.


DNA-fingerprinting analysis can be used to identify fish species, but extensive databases on the sequence of DNA of many commercially important species are a prerequisite.