A chemist is studying a macromolecule that has been isolated from a cell. Which observation would provide the STRONGEST evidence that the role of the macromolecule is to store genetic information?

A macromolecule that can store genetic information must be a DNA or RNA molecule. So, the chemist can confirm if the macromolecule is DNA/RNA by using basic DNA/RNA detection methods. Some of them are

DNA precipitation
UV- Vis Spectrophotometric analysis
Fluorometric analysis
DNA Gel electrophoresis

Explanation:

DNA/RNA precipitation: Precipitation method is a simple and straightforward method to test the presence of DNA/RNA in any sample. To perform this test, chilled ethanol is added in a double volume of sample with a 1/10 volume of sodium acetate. If the genetic material is present, it will precipitate in alcohol.

Spectrophotometric analysis: DNA/RNA absorbs UV light at 260nm wavelength. Thus, we can determine the presence of DNA by taking the 260/280 ratio through a spectrophotometer.

Fluorometric analysis: In this method, we can use any dye that can intercalate the DNA molecule. Later on, we can detect the dye signal using a fluorometric to confirm the presence of DNA.

Gel electrophoresis: DNA has a negative charge. In the gel-electrophoresis experiment, it will travel towards the positive electrode. Briefly, the macromolecule sample can be loaded on 0.8% agarose gel and stained with ethidium bromide. After 20 minutes, the chemist can check under UV light and if he sees a band, it confirms the presence of DNA/RNA.