• Chromosomes & Heredity: In the late 1800s, scientists knew chromosomes were involved in passing traits but weren't sure which part was responsible.
• Proteins vs. DNA: Most scientists thought proteins were the genetic material because they are complex and versatile. Think of them as a 20-color paint palette, while DNA was like a 4-color crayon box.

🎨 Real-World Example: Imagine trying to paint a masterpiece. Most would prefer a 20-color palette (proteins) over a 4-color crayon box (DNA), assuming more colors mean more creativity. But the Hershey-Chase experiment proved DNA, the simpler tool, holds the genetic information.

• T2 Bacteriophage: A fancy name for a virus attacking bacteria. It’s like a chocolate candy with a protein shell and DNA filling.
• The Plan: They used radioactive sulfur (35S) for proteins and radioactive phosphorus (32P) for DNA to figure out which part of the virus took over bacteria.
• The Method: They mixed, blended, and spun things around (like making a smoothie), then looked for the radioactive signals.

🍫 Real-World Example: Imagine you have two chocolates; one has a glowing wrapper (protein) and the other a glowing filling (DNA). You eat them and want to find out what stays in your stomach. By checking which part glows (wrapper or filling), you can tell what mattered. The DNA was what mattered here!

• Isotopes: Atoms with the same number of protons but different numbers of neutrons. Think of them as identical twins with different weights.
• Stable vs. Unstable Isotopes: Unstable ones are like shaky tables; they emit energy (radiation) to become stable.
• Radioisotopes in Research: In the 1950s, scientists used them like tracking devices to see where atoms went in biological systems.

⚛️ Real-World Example: Imagine giving two friends identical bags, but one has a GPS tracker. You can follow the one with the tracker, just like scientists used radioisotopes to track atoms in biological studies.