Alleles and Genes - 3.12, 3.13

Genetic Variation

In this course, Dr Matt Ivory (Cardiff University) introduces genetic variation, covering topics 3.12-3.16, 3.19 and 3.20 in the Pearson Edexcel GCSE Biology (9-1) Specification. We begin by: (i) explaining why there are differences in the inherited characteristics as a result of alleles, explaining key terms in the field (Topic 3.12, 3.13); before (ii) discussing describing and practising monohybrid inheritance using different representations (Topic 3.14, 3.16); before (iii) understanding some complexities of sex-linked inheritance and codominance (Topic 3.15, 3.19); and finally (iv) take a look at the ways that phenotype can vary as a result of genetic and environmental variation (Topic 3.20).

Alleles and Genes - 3.12, 3.13

In the first mini-lecture, we discuss cancer as being the result of uncontrolled cell division, as mentioned in topic 3.12 and 3.13. We begin by explaining why there are differences in the inherited characteristics as a result of alleles. To do so, we explain how genetic information is passed from parents to offspring through sex cells like egg and sperm cells, otherwise known as gametes. We then learn about some of the key terms geneticists use to understand variation and inheritance, including ‘chromosome’, ‘gene’, ‘allele’, ‘homozygous’, ‘heterozygous’, ‘genotype’, and ‘phenotype’.