Primary, secondary, tertiary & quaternary structure of proteins (WJEC)

This detailed lesson describes the different levels of protein structure and focuses on the bonds that hold these molecules in shape. Both the engaging PowerPoint and accompanying resources have been designed to cover point (i) as detailed in AS unit 1, topic 1 of the WJEC A-level Biology specification and makes continual links to previous lessons such as amino acids & peptide bonds as well as to upcoming lessons like enzymes and antibodies.

The start of the lesson focuses on a gene as a sequence of bases that code for the amino acid sequence in a polypeptide and a step by step guide is used to demonstrate how the sequences of bases in a gene acts as a template to form a sequence of codons on a mRNA strand and how this is translated into a particular sequence of amino acids known as the primary structure. The students are then challenged to apply their understanding of this process by using three more gene sequences to work out three primary structures and recognise how different genes lead to different sequences. Moving forwards, students will learn how the order of amino acids in the primary structure determines the shape of the protein molecule, through its secondary, tertiary and quaternary structure and time is taken to consider the details of each of these. There is a particular focus on the different bonds that hold the 3D shape firmly in place and a quick quiz round then introduces the importance of this shape as exemplified by enzymes, antibodies and hormones. Students will see the differences between globular and fibrous protein and again biological examples are used to increase relevance. The lesson concludes with one final quiz round called STRUC by NUMBERS where the students have to use their understanding of the protein structures to calculate a numerical answer.