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Two enzymes, P and Q, are proteins with quaternary structure which catalyse the same reaction, but they have different amino acid sequences - AQA - A-Level Biology - Question 5 - 2022 - Paper 1
Question 5
Two enzymes, P and Q, are proteins with quaternary structure which catalyse the same reaction, but they have different amino acid sequences. 1. Define the quaternar... show full transcript
Worked Solution & Example Answer:Two enzymes, P and Q, are proteins with quaternary structure which catalyse the same reaction, but they have different amino acid sequences - AQA - A-Level Biology - Question 5 - 2022 - Paper 1
Step 1
Define the quaternary structure of a protein.
Answer
The quaternary structure of a protein refers to the complex formation of two or more polypeptide chains that come together to form a functional protein. This structure may involve interactions such as hydrogen bonds, ionic bonds, and disulfide bridges between different polypeptide chains.
Step 2
Explain how two enzymes with different amino acid sequences can catalyse the same reaction.
Answer
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Both enzymes, P and Q, likely possess active sites that have similar or identical tertiary structures, allowing them to bind to the same substrate.
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Alternatively, despite differing amino acid sequences, both enzymes have similar functional regions that enable them to form enzyme-substrate complexes with the same substrate.
Step 3
Describe what the scientists should place in the control tubes in this investigation.
Answer
The scientists should use:
- A buffer solution to maintain a consistent pH.
- The same concentration/mass of the substrate at the beginning of the reaction.
- A sample containing denatured enzyme to show the baseline reaction without enzyme activity.
Step 4
Give three conclusions you can make from Figure 8.
Answer
- Both enzymes P and Q demonstrate activity at both pH levels, but the efficiency varies between them.
- Enzyme P shows greater activity at pH 8.4 compared to pH 7.5, indicating a preference for alkaline conditions.
- Enzyme Q exhibits less activity at both pH levels compared to enzyme P, showing that it may be less effective or stable under these conditions.