You are given two solutions containing different purified DNAs. One is from the bacterium P. aeruginosa and has a G + C composition of 68%, whereas the other is from a mammal and has G + C composition of 42%. You measure the UV absorbance of each solution as a function of increasing the temperature. Which solution will yield the higher Tm value and why?

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Biology

21 July, 18:07

You are given two solutions containing different purified DNAs. One is from the bacterium P. aeruginosa and has a G + C composition of 68%, whereas the other is from a mammal and has G + C composition of 42%. You measure the UV absorbance of each solution as a function of increasing the temperature. Which solution will yield the higher Tm value and why?

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Maxim Miles · Answer 1

The solution of P. aeruginosa will yield higher Tm value.

Explanation:

The solution of P. aeruginosa contain 68% G+C composition as a result the DNA of P. aeruginosa is more stable than the DNA of mammal contain only 42% G+C composition. G+C composition is most stable because guanine is linked to cytosine by 3 hydrogen bonds whereas adenine linked to thymine by 2 hydrogen bonds.

As P. aeruginosa DNA is more stable than mammalian DNA, as a result the DNA solution of P. aeruginosa will yield high Tm (melting temperature) value than that of mammalian DNA.