Producing DNA fragments (AQA A-level Biology)

This detailed lesson explores how a range of methods are used to produce fragments of DNA as part of the recombinant DNA technology process. Both the engaging PowerPoint and accompanying resources have been written to cover the first part of point 8.4.1 of the AQA A-level Biology specification and also provides information that will prove useful for the other lessons in this sub-topic on the polymerase chain reaction and using transformed host cells.

The lesson begins with a definition of recombinant DNA technology so that students can begin to understand how this process involves the transfer of DNA fragments from one species to another. Links are made to the genetic code and transcription and translation mechanisms, which were met in topic 4, in order to explain how the transferred gene can be translated in the transgenic organism. Moving forwards, the method involving reverse transcriptase and DNA polymerase is introduced and their knowledge of the structure of the polynucleotides and the roles of enzymes is challenged through questions and discussion points. Restriction enzymes are then introduced and time is taken to look at the structure of a restriction site as well as the production of sticky ends due to the staggered cut on the DNA. A series of exam-style questions with displayed mark schemes are used to allow the students to assess their current understanding. The final part of the lesson looks at the production of synthetic genes of any sequence using gene machines and a series of application questions are used to push the students to consider how this advance in technology could be utilised.

As well as understanding and prior knowledge checks, quick quiz competitions are used throughout the lesson to introduce key terms such as cDNA and EcoR1 in a memorable way.