For a science fair project, two students decided to repeat the Hershey and Chase experiment, with modifications. They decided to
label the nitrogenous base of the DNA, rather than the phosphate. They reasoned that each nucleotide has only one phosphate and two to five nitrogenous bases. Thus, labeling the nitrogenous bases would provide a stronger signal than labeling the phosphates. Why won't this experiment work?
The aim of the Hershey and Chase experiment was to show that DNA and not proteins are the genetic material.
Proteins are made up of amino acids which also has a nitrogenous base. Since the whole point of the experiment was to differentiate between the two i.e. show which one is the genetic material, it would be impossible to differentiate between DNA and proteins if the nitrogenous base was labelled.
The formation of a gas is a clue to chemical changes. The bubbles of gas that you observed form when an antacid is dropped into water is an example of change. ... After ice melts into liquid water, you can refreeze it into solid ice if the temperature drops. Freezing and melting are physical changes.
