Hey, future scientists! Ready to unravel the mysteries of DNA? Put on your lab coats and dive into the exciting world of biology with Chargaff's discoveries and how they changed the way we view genetic material. Trust me, it's like a detective novel, but with molecules!

• What Was It? The idea that DNA had a repeating sequence of four bases (A, T, C, and G) in equal numbers.
• Problem? Too boring and simple to contain all the instructions for life. Imagine building an entire city with only four types of Lego bricks – impossible, right?

• The Suspect: DNA. What if it's not made up of equal parts of four bases?
• The Detective: Erwin Chargaff.
• The Evidence
  • Compared base composition in various species.
  • Found that the amount of adenine (A) is equal to thymine (T), and the amount of guanine (G) is equal to cytosine (C).

• Comparing Prokaryotes & Eukaryotes: Look at the base composition of Mycobacterium tuberculosis (a prokaryote) vs. eukaryotes in Table 2. You'll see some differences. Just like comparing apples and oranges – they're both fruit but different!

• Calculating Ratios: (A + G)/(T + C) for humans & Mycobacterium tuberculosis. This will give you a value that reflects the purine to pyrimidine ratio.

• Evaluating Equal Amounts Claim: Adenine and thymine, guanine and cytosine are equal in DNA of eukaryotes and prokaryotes. Like two pairs of shoes – one pair of sneakers and one pair of boots!

• Explaining Ratios: The base pairs A-T and G-C explain the ratios. It's like matching puzzle pieces; they have to fit together in a specific way!

• Falsifying Tetranucleotide Hypothesis: The unequal base amounts in DNA reject the old idea. Boom! Case closed!

• Differences in Viruses: Bacteriophage T2 vs. polio viruses might differ due to different functions or host organisms. Like using different tools for different jobs!