This clear and concise lesson explains how the inheritance of two or more genes that have loci on the same autosome demonstrates autosomal linkage. The engaging PowerPoint and associated resource have been designed to cover the part of point 7.1 of the AQA A-level Biology specification which states that students should be able to use fully-labelled genetic diagrams to interpret the results of crosses involving autosomal linkage.
This is a topic which can cause confusion for students so time was taken in the design to split the concept into small chunks. There is a clear focus on how the number of original phenotypes and recombinants can be used to determine linkage and suggest how the loci of the two genes compare. Important links to other topics such as crossing over in meiosis are made to enable students to understand how the random formation of the chiasma determines whether new phenotypes will be seen in the offspring or not. Linkage is an important cause of variation and the difference between observed and expected results and this is emphasised on a number of occasions. The main task of the lesson acts as an understanding check where students are challenged to analyse a set of results involving the inheritance of the ABO blood group gene and the nail-patella syndrome gene to determine whether they have loci on the same chromosome and if so, how close their loci would appear to be.
This lesson has been written to tie in with the other 6 lessons from topic 7.1 (Inheritance) and these have also been uploaded