Biological Molecules

Biological molecules is often the first biological topic taught at level 3/KS5 and one where a lack of knowledge and understanding will undermine future understanding. It is essential that students can recognise and explain how the structure of biological molecules is then related to properties and to the functions these molecules perform.

Students can often find this topic quite overwhelming at first. There is a great deal of new vocabulary to learn with a need for precise and accurate recall of molecular structures. Regular review of the basic facts and fundamental points is essential to help build the confidence of students, as is an appreciation of the ‘big picture’ and how these molecules relate to each other in terms of both their similarities and differences. Approaching and revisiting the concepts in different ways (particularly avoiding just learning structural formulae by rote) can help students to view things in less abstract terms. Modelling activities such as the use of molecular model kits (or through the use of cheap alternatives such as plasticine, sweets and straws) are particularly good for this purpose.

Note that this topic relates to other resource listings, particularly DNA and enzymes. It is recommended that these resource listings are viewed alongside this one when planning out schemes of learning.

Whilst this list provides a source of information and ideas for experimental work, it is important to note that recommendations can date very quickly. Do NOT follow suggestions which conflict with current advice from CLEAPSS, SSERC or other recent safety guides. eLibrary users are responsible for ensuring that any activity, including practical work, which they carry out is consistent with current regulations related to Health and Safety and that they carry an appropriate risk assessment. Further information is provided in our Health and Safety guidance.

Although this is written for OCR A-Level Biology, the activities listed in the guide are suitable for any level 3 course. A variety of creative activities are presented, ranging from practical food test activities (often with an unusual context such as the use of Benedict’s test for medical purposes, different approaches to the Biruet test and synoptic approaches to the iodine test) to modelling condensation and hydrolysis using balls and balloons. Chromatography is also referenced along with an ionic bingo game template. This would be a useful initial reference when planning practical activity for this topic.

This page form the Protein Databank in Europe (PDBE) provides various useful activities that can be used to reinforce knowledge and understanding of biological molecules with students. Among the resources listed here, you will find a fold-a-protein and fold-a-virus activity, a protein colouring book and a range of other resources suitable for level 3 study

This ‘Jelly Mods’ biological molecules activity from OCR allows students to build biological molecules of varying complexity and explore the concepts of structure and bonding. Jelly based sweets of different colours are used to represent different atoms, providing a fun, cheap and edible alternative to traditional molecular model kits. There is a student worksheet with questions and a teacher guide. There is also a starter or plenary ‘bingo’ activity that consolidates key terms and some questions and answers.

Although the structure and properties of water do not always feature in specifications, it is essential that students have an understanding of hydrogen bonding and the cohesive nature of water molecules to explain how and why other molecules behave in the way they do. Hydrogen bonding is a feature of protein secondary & tertiary structure and hydrophobic interactions are fundamental for explaining cell membrane structure. In this simple experiment, students can be asked to predict and then count how many drops of water they can place on a penny. Surface tension is caused by hydrogen bonds between adjacent water molecules, with the result that a surprising volume of water can be placed on the penny before the water spills over the edge. As an extension, students could also be asked to repeat the experiment but add a drop of detergent to the water after a few drops have been added, with the result that the surface tension is immediately broken. A follow up discussion on the results, the structure and the properties of water should then help to clarify the nature of hydrogen bonding.

The Protein Data Bank is a resource that provides research grade archived information about the 3D shapes of proteins, nucleic acids and complex assemblies. Named proteins can be searched in the database and comprehensive information including 3D structure, amino acid sequencing, genome and gene loci can be visualised. In terms of classroom teaching, the 3D viewer provides a powerful way of illustrating the complexity of tertiary and quaternary structure proteins and relating these to primary structure, as the sequence of amino acids for a selected part of the model is displayed in the viewer. More detailed sequencing and genomic information can be obtained from the relevant tabs. This could be turned into an activity whereby students are provided with some sequence information for different proteins and asked to use the data base to find out some key information (e.g. chromosome position of gene, function of protein, number of disulphide bridges, etc). Such an activity from SAPS can be found HERE

Quality AssuredCategory:SciencePublisher:Wellcome Trust

This issue of the Big Picture magazine focuses on proteins, in particular the role of different proteins within the body.

There is a lot of information within this resource. Using individual articles, or perhaps a few related articles, would be a good way to make use of this excellent resource.

This practical activity would complement work on biological molecules and provides a very useful activity for developing required mathematical skills. The practical requires the use of a colorimeter. If only one colorimeter is available, select one group to work with that and compare their results to those of other groups. Let each group acquire a set of results and then collate the class data to a spreadsheet visible to all.

The practical itself is relatively straightforward and should not present too much of a challenge for level 3/KS5 students. Using the results students should then be able to construct a calibration curve from which to estimate the concentration of protein in the known and unknown samples of milk powder.

This is a clear and concise website which has all the detail required for level 3 study. There are questions that can be answered at the end of sections.

The website could be given to students purely for revision. Alternatively they could be asked to evaluate the questions that are included and come up with three better questions to ask their peers. Groups of students could look at different sections and evaluate these against some criteria or questions. For example, is there anything missing? What could be added? Are all the terms used correct?

The Association for British Pharmaceutical Industry (ABPI) website has a topic entitled Chemistry of life. The pages within this topic provide a wealth of relevant material on biological molecules. Students could be directed to specific pages, such as page three for water or page five for carbohydrates. There are useful animations on some pages to illustrate particular reactions such as condensation and hydrolysis.

There are also activities on the website pages that students could be directed to , which would be suitable for both directed study or in class activities. For example, students are asked to produce an info graphic on the topic of carbohydrates (there are examples of other websites with info graphics).