Final answer:
Erwin Chargaff used a technique involving the quantification of DNA's nucleobases to disprove the tetranucleotide model, which claimed a repeating pattern of equal proportions of nucleobases. His findings, known as Chargaff's rules, showed A=T and G=C ratios, which were crucial for Watson and Crick's double helix model of DNA.
Step-by-step explanation:
How Erwin Chargaff Disproved the Tetranucleotide Hypothesis
Erwin Chargaff and colleagues utilized a new biochemistry technique that involved isolating and quantifying the individual nucleobases of DNA to discredit the tetranucleotide model.
The tetranucleotide hypothesis suggested that DNA was composed of equal shares of guanine (G), adenine (A), thymine (T), and cytosine (C) in a repeating pattern.
Chargaff discredited this by meticulously analyzing the base composition of DNA from various species.
His research demonstrated that the four nucleobases were not present in equal quantities.
Instead, he discovered that the amount of adenine always equals the amount of thymine, and the amount of guanine always equals the amount of cytosine (Chargaff's rules).
These findings were instrumental for James Watson and Francis Crick in their development of the double helix model of DNA,
Where these base pairing rules allowed for the establishment of a complementary and antiparallel strand structure, leading to the stable structure of the double helix.
Chargaff's data exhibited a unique pattern of base ratios, which were consistent across species: the A/T and G/C ratios were always one, and this applied to the ratios of (A+C)/(G+T) and (A+G)/(C+T) as well.
Through precision analysis, as mentioned in the Journal of Biological Chemistry by Chargaff et al., the standard deviations and total fractions for each nucleobase were meticulously calculated, paving the way for discrediting the tetranucleotide hypothesis.