Gel electrophoresis (OCR A-level Biology)

This fully-resourced lesson explains how gel electrophoresis is used to separate DNA fragments or proteins and explores its applications in genetic fingerprinting. The engaging and detailed PowerPoint and accompanying resources have been written to cover point 6.1.3 (e) of the OCR A-level Biology A specification

The steps of the genetic fingerprinting process is covered the whole lesson but the main focus is the use of gel electrophoresis within this process. Students will be introduced to STRs and will come to recognise their usefulness in human identification as a result of the variability between individuals. Moving forwards, the involvement of the PCR is discussed and students are challenged on their knowledge of this process as it was encountered in a previous lesson. A brief outline of the role of restriction enzymes is provided to support students when these key gene technology enzymes are met in more detail later in the module. The main section of the lesson focuses on the use of gel electrophoresis to separate DNA fragments (as well as proteins) and the key ideas of separation due to differences in base pair length or molecular mass are discussed and explained. As well as current understanding checks, an application question involving Huntington’s disease is used to challenge their ability to apply their knowledge of the process to an unfamiliar situation. The remainder of the lesson describes how the DNA is transferred to a membrane and hybridisation probes are used to create a pattern on the X-ray film.

Time has been taken to make continuous links to the previous lessons in module 6.1.3 as well as those from module 2.1.3 where DNA, RNA and protein synthesis were introduced.