Active transport (CIE International A-level Biology)

This fully-resourced lesson describes the processes of active transport, endocytosis and exocytosis and explains the need for ATP. The PowerPoint and accompanying worksheets have been designed to cover the second part of point 4.2 (a) of the CIE International A-level Biology specification. The first part of 4.2 (a), concerning simple and facilitated diffusion, was covered in the previous lesson.

The start of the lesson challenges the students to use their prior knowledge of biological molecules to come up with the abbreviation ATP and they will learn that this is a phosphorylated nucleotide that contains adenine, ribose and three phosphate groups. Students may not have known this as the energy currency from GCSE so time is taken to explain that this molecule must be broken down to release energy and students are challenged to recall which type of reaction will be involved and to predict the products of such a reaction. This hydrolysis of ATP can be coupled to energy-requiring reactions within the cell and the rest of the lesson focuses on the use of this energy for active transport, endocytosis and exocytosis. Students are challenged to answer a series of questions which compare active transport against the forms of passive transport and to use data from a bar chart to support this form of transport. In answering these questions they will discover that carrier proteins are specific to certain molecules and time is taken to look at the exact mechanism of these transmembrane proteins. A quick quiz round introduces endocytosis and the students will see how vesicles are involved along with the energy source of ATP to move large substances in or out of the cell. The lesson concludes with a link to a future topic as the students are shown how exocytosis is involved in a synapse.