Chemistry 9701 · AS & A Level · Analytical techniques

Analytical techniques — practice question

Electrophoresis can be used to separate a mixture of amino acids.
(a)[3]

In an electrophoresis experiment, different amino acids move in different directions, different amino acids move at different speeds, and some amino acids do not move at all. Explain these observations.

(b(i))[2]

A mixture of amino acids can also be separated by thin-layer chromatography. Identify the mobile phase and the stationary phase in this type of chromatography.

(b(ii))[1]

What is the process by which thin-layer chromatography can separate a mixture?

(c)[3]

State three structural features of DNA.

(d)[2]

Some diseases are caused by a mutation in the DNA base sequence which results in one amino acid being replaced by another during protein synthesis. Suggest what changes in the interactions that form the tertiary structure would result from a mutation that replaced a valine residue with a serine residue.

Worked solution & mark scheme

This 11-mark question has a full step-by-step worked solution and mark scheme. One marking point: Amino acids move differently because of charge/size; zwitterions may remain stationary

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