Question

“A very small sample of tissue or even a drop of blood can help determine paternity”. Provide a scientific explanation to substantiate the statement.

Answer 1

A very small sample of tissue or even a drop of blood can help determine paternity by DNA fingerprinting. The DNA is extracted from the nuclei of cells or blood cells. The DNA molecules are first broken with the help of an enzyme restriction endonuclease, which cuts them into fragments which contain variable number tandem repeats (VNTRs). The fragments are separated according to size by gel electrophoresis and are amplified by the polymerase chain reaction (PCR) technique. They are then treated with alkaline chemicals to split them into single-stranded DNAs and are transferred onto a nylon membrane. An X-ray film is exposed to the nylon membrane on which the dark bands represent the DNA fingerprints.