Here's why:
* Proteins were known to be complex: Proteins have a diverse array of structures and functions, making them seem like a good candidate for carrying the complex instructions for life.
* Proteins were abundant: Proteins are found in all living organisms and play many vital roles.
* DNA was initially thought to be too simple: DNA was known to be a relatively simple molecule, with only four building blocks. It seemed unlikely that it could carry the vast amount of information needed to govern life.
However, the famous Hershey-Chase experiment in 1952 conclusively demonstrated that DNA, not protein, is the carrier of genetic information.
