When considering spectrophotometry methods to measure dna concentration, we know that nucleic acid absorbs light mostly at wavelength, while protein does so at wavelength. we want this ratio to be above which indicates good nucleuc acid purity.

Nucleic acid: 260nM ; Protein 280nM and ration must be in between 1.8 to 2.

Explanation:

The spectrophotometry method that is used to measure the purity of the substance by measuring the absorbance of a particular wavelength of light.

A beam of light is passed through the sample solution. The principle is that the substance might absorb light or transmit light.

When a solution of DNA is kept under spectrophotometry then The wavelength of light absorbed by DNA is 260 nM and protein is 280 nM and their ratio should be in between 1.8 to 2.

A value in between 1.8 to 2 indicates the solution is pure and has no contamination in it.

bacterium is not correct