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B1.2.1—Generalized amino acid structure

Amino acids share an alpha-carbon framework with amine, carboxyl, hydrogen and R-group attachments that determine protein chemistry and molecular structure.

Syllabus
First assessment 2025
Objective
B1.2.1
Level
SL

Exam analysis

Chance of appearing4%of analysed past papers
Latest appearanceNovember 2022
Most common paperPaper1
Typical marks1

Common command terms

  • Draw
  • Identify

Scoring notes

Common mistake
Omitting either the amine group or carboxyl group when drawing a generalized amino acid.

Recent exam appearances

November 2022Paper2 ["SL"] · TZ03(a)[ 1 ]B1.2.1—Generalized amino acid structure
May 2017Paper2 ["SL"] · TZ25(a)[ 3 ]B1.2.1—Generalized amino acid structure
May 2015Paper1 ["SL"] · TZ29[ 1 ]B1.2.1—Generalized amino acid structure
May 2010Paper1 ["SL"] · TZ27[ 1 ]B1.2.1—Generalized amino acid structure
May 2010Paper1 ["SL"] · TZ17[ 1 ]B1.2.1—Generalized amino acid structure
Practice this objective

Coverage 2010–2022 · Updated 15 Jul 2026

Concept essentials

  • All amino acids have a central alpha carbon bonded to amine, carboxyl, hydrogen and R-group attachments.
  • The R-group is the variable part that gives amino acids different properties.
  • Proteins contain nitrogen, and some amino acids contain sulfur.
  • Amino acid diagrams must show the functional groups attached to the central carbon.
ConceptIB Biology SL