A spectrophotometer is an instrument that can determine the purity of a DNA sample by measuring the ratio of two wavelengths. The wavelength absorbance ratio is….
A) 260 nm divided by the 280 nm ratio
B) 200 nm t divided by the 300 nm ratio
C) 280 nm divided by the 300 nm ratio
D) 220 nm divided by the 260 nm ratio
E) none of the above

Question

Quizplus · Accepted Answer

The ratio used to determine DNA purity is the 260 nm divided by the 280 nm ratio. The absorption at 260 nm is primarily due to the DNA nucleotides, while the absorption at 280 nm is primarily due to the presence of protein contamination. A pure DNA sample will have a high absorbance at 260 nm and a low absorbance at 280 nm, resulting in a high 260/280 ratio.

A Spectrophotometer Is an Instrument That Can Determine the Purity