Open Question
Fill in the groups for the predominant structure of Ala at pH 13?
1
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3. Amino Acids
Zwitterion
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Which of the following best describes a zwitterion?
A
A molecule that is uncharged at all pH values.
B
A molecule that carries only a positive charge.
C
A molecule that carries only a negative charge.
D
A molecule that contains both a positive and a negative charge, but is overall electrically neutral.
Verified step by step guidance1
Understand the term 'zwitterion': A zwitterion is a molecule that contains both a positive and a negative charge within the same structure, but the overall charge of the molecule is neutral.
Recognize that zwitterions are common in amino acids: At a specific pH, known as the isoelectric point, amino acids exist as zwitterions. For example, the amino group (-NH₃⁺) is positively charged, and the carboxyl group (-COO⁻) is negatively charged.
Consider the role of pH: The zwitterionic form of a molecule depends on the pH of the environment. At low pH, the molecule may carry a net positive charge, and at high pH, it may carry a net negative charge. At the isoelectric point, the molecule is electrically neutral but contains both charges.
Compare the options provided: Eliminate choices that describe molecules as uncharged at all pH values, or carrying only positive or negative charges, as these do not fit the definition of a zwitterion.
Select the correct answer: A molecule that contains both a positive and a negative charge, but is overall electrically neutral, best describes a zwitterion.
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