Genetic inheritance (AQA GCSE Combined Science)

This lesson introduces and explains the meaning of 11 key terms associated with the genetic inheritance topic. The PowerPoint and accompanying resources have been designed to cover point 6.1.6 of the AQA GCSE Combined Science specification and include explanations of genome, chromosome, gene, allele, genotype, homozygous, heterozygous, phenotype, dominant, recessive and gamete.

The key term, genome, was met earlier in topic 6 so the lesson begins with a knowledge retrieval with the definition for this term. As the genome is the entire DNA of an organism, the next task challenges the students to identify three errors in a passage about DNA. This challenges their recall of the structure of this chemical as a double helix, its location in an eukaryotic cell in the nucleus and an understanding that the gene codes for the sequence of amino acids in a specific protein. This leads into discussions about chromosomes and genes and time is taken to explain that homologous chromosomes have the same genes at the exact same gene loci. The students will learn that alternative forms of the gene (alleles) can be found at these loci and that these structures explain the differences in inherited characteristics. Moving forwards, the main section of the lesson describes the link between the dominant and recessive alleles, homozygous and heterozygous genotypes, and the physical expression as the phenotype. The final key term is gamete, and the students are challenged to recognise a definition for this term using their knowledge of meiosis. Two progress and understanding checks complete the lesson and check on the students’ ability to recognise and write definitions for these 11 terms and to use them accurately in a written description