Action of antibiotics (Edexcel A-level Biology B)

This lesson describes the action of bactericidal and bacteriostatic antibiotics, as illustrated by penicillin and tetracycline. The engaging PowerPoint and accompanying resources have been designed to cover point 6.3 (i) of the Edexcel A-level Biology B specification but it has been specifically planned to make continual links to earlier lessons in topic 6 and to protein synthesis as covered in topic 1

The lesson begins by challenging the students to use their general biological knowledge and any available sources to identify the suffixes cidal and static. Students will learn that when the prefix is added, these form the full names of two types of antibiotics. Their understanding of terminology is tested further as they have to recognise that Polymyxin B is an example of a bactericidal antibiotic as its actions would result in the death of the bacterial cell. Time is then taken to describe the action of penicillin and students will learn how inhibitors and modified versions of this antibiotic are used to overcome those bacteria who have resistance. Tetracycline is used as the example of a bacteriostatic antibiotic and students will discover that its prevention of the binding of tRNA that inhibits protein synthesis and this reduction and stopping of growth and reproduction is synonymous with these drugs. Students are challenged on their knowledge of translation and will also be given time for a class discussion to understand that these antibiotics encourage the body’s immune system to overcome the pathogen in natural, active immunity.

The final part of the lesson uses a quick quiz competition and a series of exam-style questions to ensure that students can recognise these different types of antibiotics from descriptions.