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D1.2.11—Mutations changing protein structure

Mutations can alter codons, change amino acid sequence, disrupt protein structure and produce disease phenotypes such as sickle-cell anemia in humans.

Syllabus
First assessment 2025
Objective
D1.2.11
Level
SL

Exam analysis

Chance of appearing4%of analysed past papers
Latest appearanceMay 2023
Most common paperPaper2
Typical marks1–5

Common command terms

  • Outline
  • Explain

Scoring notes

Common mistake
Stopping at the DNA mutation without tracing the change through mRNA codon and amino acid sequence.

Recent exam appearances

May 2023Paper1 ["SL"] · TZ214[ 1 ]D1.2.11—Mutations changing protein structure
November 2014Paper2 ["SL"] · TZ05(c)[ 8 ]D1.2.11—Mutations changing protein structure
May 2014Paper2 ["SL"] · TZ13(c)[ 3 ]D1.2.11—Mutations changing protein structure
May 2011Paper2 ["SL"] · TZ16(c)[ 5 ]D1.2.11—Mutations changing protein structure
May 2011Paper1 ["SL"] · TZ217[ 1 ]D1.2.11—Mutations changing protein structure
Practice this objective

Coverage 2011–2023 · Updated 16 Jul 2026

Concept essentials

  • A base substitution can change one mRNA codon.
  • A changed codon may replace one amino acid in a polypeptide.
  • Sickle-cell haemoglobin contains valine instead of glutamic acid at a key position.
  • Protein structure changes can alter cell shape and physiological function.
ConceptIB Biology SL