Lab · Teaching
Three short activities for lessons and school talks: an epidemic, Mendel's peas and a mutation in the beta-globin gene.
Epidemic: Deterministic SIR model (Kermack-McKendrick) integrated with a 0.1-day step. Herd immunity threshold = (1 − 1/R) / vaccine effectiveness. The model leaves out age groups, seasons and waning immunity. Genetics: Seed colour: Y yellow (dominant), y green. Seed shape: R round (dominant), r wrinkled. With two genes, independent assortment is assumed. Chi-square goodness of fit on the phenotype classes, with k − 1 degrees of freedom. Mutation: The reference is the start of the human HBB coding sequence (beta-globin, NCBI NM_000518), 31 codons. Codons are numbered as in the medical literature, with the start codon as 0. Haemoglobin S (Glu6Val), haemoglobin C (Glu6Lys) and the codon 17 nonsense mutation (Lys17Ter, a cause of beta-thalassaemia) are real variants. The silent change at codon 3 is an example made up for the exercise.