question_answer 31)

  Can a disease be detected before its symtoms appear? Explain the principle involved.

Answer:

                  When the symptoms of the disease are not yet visible, the pathogen concentration is very low so, the detection by conventional diagnostic tests is very difficult. However, detection of a disease before the appearance of symptoms is possible by the amplification of victim's nucleic acid by PCR .The principle involved here is that a single DNA molecule can be copied endlessly in a test tube using primers, DNA polymerase enzyme and free nucleotides. The desired DMA of the pathogen is amplified by PCR from a limited amount of DNA template.