Revised 2008/05/22
More than any aspect of biochemistry you have studied so far, metabolism will tax your knowledge of organic structure and reaction mechanisms. If you can see familiar reaction types in somewhat complex metabolic reactions, you can make sense of what at first appear to be unfamiliar processes. Each metabolic pathway usually includes several reactions closely related to those you have studied in organic chemistry. The Essential Review sections of these Learning Strategies will provide lists of specific reaction types you should review as an aid to understanding metabolic reactions.
As you begin each of the chapters on metabolic pathways, look for the first chart or figure that shows the structures of all intermediates in the chapter's central pathway. As soon as you encounter this chart, MEMORIZE IT. Specifically, for each major pathway, memorize the following:
In learning the structures of intermediates, don't memorize all the structures as if they were unrelated. Instead, memorize how to transform each intermediate into the next. Each reaction is relatively simple. Only a small part of a molecule changes in each step. So memorize the series of operations that transforms each intermediate into the next.
When you complete your memory work, you should be able to write out a chart of the pathway, with all the information described above, in no more than 10 minutes.
You may be thinking that this task is too onerous to comtemplate. But in the end, it's a time and labor saver. If you will take the time to carry out this memory task when you first encounter each major pathway, you will have a much easier time reading the rest of the chapter with understanding. You will find that as you read about the details of specific reactions, you have a sense of where you are, and where the current subject fits into the larger scheme of the pathway. The biggest problem in learning metabolism is developing a view that encompasses both the forest and the trees. Memorizing the major pathways will help you connect a global view of the whole pathway (the forest) with the individual reactions (the trees).
Each time we enter a new topic in metabolism, your instructor will specify the pathway or pathways you should memorize. At the beginning of the first class on the new topic, you will have 10 minutes to write out the pathway, with all the details listed above.
Memorizing pathways is primarily an aid to learning more about them. Questions on exams are usually at a higher level than mere memory work. On exams that cover topics in metabolism, your instructor will provide complete charts of any pathways you need for answering exam questions. So there is no need to come to exams prepared to regurgitate pathways. Instead, come prepared to use your experience with pathways -- gained by memory work, reading, and problem solving -- to answer questions, interpret data, and solve problems about them.
As you study, pay particular attention to these five elements of all pathways. If you have a good grasp of each element, then you are on your way to a good understanding of the pathway.