NEET BIOLOGY

Detailed explanation-1: -In 1952, Alfred Hershey and Martha Chase took an effort to find the genetic material in organisms. Their experiments led to an unequivocal proof to DNA as genetic material. Bacteriophages (viruses that affect bacteria) were the key element for Hershey and Chase experiment.

Detailed explanation-2: -In their experiments, Hershey and Chase showed that when bacteriophages, which are composed of DNA and protein, infect bacteria, their DNA enters the host bacterial cell, but most of their protein does not. Hershey and Chase and subsequent discoveries all served to prove that DNA is the hereditary material.

Detailed explanation-3: -Hershey and Chase found that when bacteriophages containing 32P (radioactive), were allowed to infect nonradioactive bacteria, all the infected cells became radioactive and, in fact, much of the radioactivity was passed on to the next generation of bacteriophages.

Detailed explanation-4: -The protein shell of the virus was tagged with radioactive sulphur, and this ended up in the supernatant. The heavier bacterial cells formed the pellet, so Hershey and Chase knew that DNA was the genetic material of the virus, as the phosphorus was found there.