Question

"A very small sample of tissue or even a drop of blood can help determine paternity." Provide a scientific explanation to substantiate how it is possible.

Answer 1

A very small sample of DNA obtained from a tissue or even a drop of blood can serve as a source for paternity testing. By using the techniques of PCR and DNA fingerprinting, we can determine the paternity of any individual.

The steps are as follows -

• The first step includes the extraction of DNA from the cells or blood.
• The DNA molecules are then broken into small fragments that contain a variable number of tandem repeats (VNTR's).
• The DNA fragments are then separated by gel electrophoresis.
• These DNA fragments are multiplied using PCR.
• They are then converted into single-stranded DNA by treatment with alkaline chemicals.
• It is followed by transferring these fragments to the nylon membrane.
• The nylon membrane is exposed to X-ray film which creates dark-colored bands called fingerprints.
• These fingerprints can then be used to determine paternity.