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Electrophoresis is a technique which can be used to separate amino acids or peptide fragments present in a mixture - CIE - A-Level Chemistry - Question 7 - 2013 - Paper 1
Question 7
Electrophoresis is a technique which can be used to separate amino acids or peptide fragments present in a mixture. (a) Draw a diagram to show the apparatus used to... show full transcript
Worked Solution & Example Answer:Electrophoresis is a technique which can be used to separate amino acids or peptide fragments present in a mixture - CIE - A-Level Chemistry - Question 7 - 2013 - Paper 1
Step 1
Draw a diagram to show the apparatus used to carry out electrophoresis.
Answer
To properly illustrate the setup for electrophoresis, you should include the following components in your diagram:
- Power Supply: Ensure to label this component as it provides the necessary electric field for the process.
- Electrode: This includes both an anode and a cathode where the electric current is applied.
- Gel or Filter Paper: Indicate this as the medium through which the amino acids or peptide fragments will migrate.
- Sample Mixture: Clearly label where the amino acid mixture is placed within the gel.
- Buffer Solution: Mark this to depict the solution that maintains pH and ionic strength.
Step 2
How far an amino acid will travel during electrophoresis depends on the pH of the solution. For a given potential difference, state two other factors that will affect how far a given amino acid travels in a fixed time during electrophoresis.
Answer
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Size/Molecular Weight of the Amino Acid Species: Larger amino acids will travel slower through the gel compared to smaller ones due to greater resistance.
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Charge on the Amino Acid Species: The net charge of the amino acid affects how strongly it is attracted or repelled by the electrodes, influencing its migration distance.
Step 3
State what is meant by the term partition coefficient.
Answer
The partition coefficient (PC) is defined as the ratio of the concentration of a solute in two immiscible solvents at equilibrium. Mathematically, it can be expressed as:
This coefficient provides insight into how a solute is distributed between two phases, indicative of its polarity and solubility in the respective solvents.