Multiple Choice
Which of the following is NOT attached to the central (alpha) carbon atom in a standard amino acid?
68
views
3. Amino Acids
Amino Acid Configuration
Struggling with Biochemistry?
Join thousands of students who trust us to help them ace their exams!Watch the first videoMultiple Choice
Which part of an amino acid is always acidic?
A
The amino group (–NH₂)
B
The carboxyl group (–COOH)
C
The hydrogen atom attached to the alpha carbon
D
The side chain (R group)
Verified step by step guidance1
Understand the structure of an amino acid: Amino acids consist of a central alpha carbon bonded to four groups: an amino group (–NH₂), a carboxyl group (–COOH), a hydrogen atom, and a variable side chain (R group).
Recall the chemical properties of the carboxyl group (–COOH): The carboxyl group contains a hydroxyl (-OH) attached to a carbonyl (-C=O). It is acidic because it can donate a proton (H⁺) to the surrounding environment, forming a carboxylate ion (–COO⁻).
Compare the amino group (–NH₂): The amino group is basic, not acidic, because it can accept a proton (H⁺) to form –NH₃⁺.
Evaluate the hydrogen atom attached to the alpha carbon: This hydrogen atom is neutral and does not exhibit acidic or basic properties.
Analyze the side chain (R group): The acidity or basicity of the side chain depends on its specific chemical structure, but it is not universally acidic across all amino acids. Therefore, the carboxyl group (–COOH) is the part of an amino acid that is always acidic.
11:4mWatch next
Master L & D Amino Acid Configurations with a bite sized video explanation from Jason
Start learningRelated Videos
Related Practice
Amino Acid Configuration practice set
Problem sets built by lead tutorsExpert video explanations