3.4.3 L1 Gene mutation (AQA A-level Biology)

A fully resourced A‑level Biology lesson covering gene mutations, including substitution, deletion and chromosome mutations, designed for mixed‑ability classes. The lesson begins with a retrieval starter and an engaging hook on L1 jumping genes, prompting students to think about how mobile genetic elements can cause mutations. Key terms are introduced clearly, followed by step‑by‑step explanations of gene mutations, frameshifts, silent mutations and chromosome‑level changes such as polyploidy and non‑disjunction.
Students practise identifying mutation types from real DNA sequences, use the genetic code to predict amino acid changes, and apply understanding through think‑pair‑share tasks, MCQs, and consolidated written questions. Model answers and diagrams support all learners, while extension questions challenge higher‑ability students.

Learning Objectives
By the end of this lesson, students will be able to:

• Describe gene mutations and explain when and how they occur (replication errors, mutagenic agents).
• Explain how substitution and deletion mutations alter DNA and how these changes affect amino acid sequences in polypeptides.
• Explain why some mutations do not change the amino acid sequence, including silent mutations, intron mutations and degenerate codons.
• Describe chromosome mutations, including polyploidy, non‑disjunction and translocation, using real biological examples such as Down syndrome.
• Apply knowledge to DNA sequences, identifying mutation types and predicting their impact on the resulting polypeptide.

This lesson includes:

• Retrieval starter & prior knowledge check
• Clear explanations with diagrams
• Interactive tasks and paired discussion
• Differentiated questions
• AfL multiple‑choice quiz with answers
• Modelled examples using real DNA sequences
• Consolidation activity and stretch questions