Question detail
Explain how the structure of an amino acid allows it to act as a zwitterion.
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
Question
Type
exam_style
Style
Topic
Amino acids, proteins and DNA (A-level only)
Question
Explain how the structure of an amino acid allows it to act as a zwitterion.
Answer
An amino acid acts as a zwitterion because it has both a positively charged amine group and a negatively charged carboxylate group at physiological pH, resulting in a net charge of zero.
Explanation
This answer is strong as it clearly describes the dual charge characteristic of zwitterions, linking it to the structure of amino acids. The question tests understanding of amino acid behavior in different pH environments, which is crucial for biochemistry.
Common mistake
Confusing Functional Groups
Students often describe amino acids without clearly identifying the presence of both amine (-NH2) and carboxylic acid (-COOH) functional groups.
To fix this, remember that an amino acid contains both an amine group and a carboxylic acid group. For example, the general structure of an amino acid can be represented as R-CH(NH2)-COOH, where R represents the variable side chain. Clearly state both functional groups when describing amino acids.
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