3. Which of the following statements best describes the charges on amino acids a

Question

3. Which of the following statements best describes the charges on amino acids at neutral pH (around 7)? A. Each amino acid contains a positively charged amine and a negatively charged carboxylic acid at neutral pH. B. For some amino acids, the amine is positively charged and the carboxylic acid is uncharged at neutral pH. C. For some amino acids, the amine is uncharged and the carboxylic acid is charged at neutral pH. D. For each amino acids, the amine is uncharged and the carboxylic acid is uncharged at neutral pH.

Explanation / Answer

C. For some amino acids, the amine is uncharged and the carboxylic acid is charged at neutral pH.

The molecule turns out to have a net negative charge

here's a quote from http://www.chemguide.co.uk/organicprops/aminoacids/acidbase.html:

"Note: You might have expected the isoelectric point to be at pH 7 - when the solution is neither acidic nor alkaline. In fact, the isoelectric point for many amino acids is about pH 6. Explaining why it isn't at pH 7 is quite long-winded and almost certainly beyond what you will need for UK A level (or its equivalent) purposes. If you are interested, the problem is discussed at the bottom of this page."

Related Questions

Navigate

• Browse (All)
• Browse 3
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.