Basic

Some amino acids have basic side groups, which means that they gain a positively charged hydrogen ion at neutral pH. One basic amino acid is arginine, which contains a long side chain composed of carbon, hydrogen, and nitrogen atoms with a positive charge at the end. Another amino acid possessing a basic side group is histidine, which is characterized by a ring structure with a positive charge. The final basic amino acid is lysine, containing a long side chain of carbon, nitrogen and hydrogen atoms like that of arginine. The positive charge on these molecules results from the addition of a hydrogen ion to the amino group found within the side chain of each amino acid.

Question 1: What makes some amino acids basic?
  1. Losing a positively charged hydrogen ion at neutral pH.
  2. Gaining a positively charged hydrogen ion at neutral pH.
  3. Losing an electron at neutral pH.
  4. Gaining an electron at neutral pH.


Answer 1 Answer - (b) Gaining a positively charged hydrogen ion at neutral pH

Question 2: ____________ and ______________ possess a long side chain group with a positive charge at the end that makes them basic at neutral pH.
  1. Histidine and arginine.
  2. Arginine and lysine.
  3. Glutamate and aspartate.
  4. Aspartate and histidine.


Answer 2 Answer - (b) Arginine and lysine

Question 3: Histidine is a basic amino acid that has a ______________ structure with a positive charge at neutral pH.
  1. long side chain
  2. aliphatic
  3. carbonyl
  4. ring


Answer 3 Answer - (d) ring