Chemistry 9701 · AS & A Level · Analytical techniques

Analytical techniques — practice question

DNA fingerprinting has grown into a key analytical technique, mainly because it is used to 'screen' crime suspects. It also has several uses in modern analysis, including establishing family relationships, medicine and archaeology.
(a)[3]

(i) DNA fingerprinting relies on an analytical technique you have studied. What is the name of this technique? (ii) To carry out DNA fingerprinting, the DNA must first be broken into shorter lengths of polynucleotides. How is this done? (iii) Which part of the DNA fragments lets them move in an electric field?

(b)[2]

(i) Indicate with an X on the diagram the lines from suspect 1 and suspect 2 that cannot show which of them was in the house. (ii) From this evidence, one suspect was arrested. Which suspect would you expect this to be? Explain your answer.

(c)[5]

A sample of a liquid, P, was discovered at the scene of the crime and analysed using mass spectrometry and NMR spectroscopy. The mass spectrum has M and M+1 peaks in the ratio of $5.1 : 0.22$, with the M peak at $m/e = 88$. The NMR spectrum is shown. Use the data to suggest a structure for P, explaining your answer. Structure of P.

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