Metabolism in BIS2A
Cellular metabolism represents roughly 1/3 of the BIS2A curriculum. While this may seem like a lot, we cover very little of what a classic course in metabolism (like BIS103) will cover, and an even smaller (really minuscule) fraction of the metabolism that occurs on the planet. What we do cover, however, is very important foundational knowledge. You will learn about some common chemical reactions that are associated with the transformation of life's molecular building blocks and about different core modes of energy transfer that you will encounter often in biology. The energy story and the design challenge rubrics introduced earlier will become increasingly important in these next few modules and beyond.
What have we learned? How will it relate to metabolism?
- We have focused on the identification and chemical properties of common biological functional groups. As we dive into metabolism, this will help you be familiar with and sometimes even predict the chemical nature/reactivity of compounds you have never seen before.
- We have practiced recognizing and classifying molecules into four major functional groups. This will help you as we begin to discuss how to build and break down these molecules.
- We have learned some basic thermodynamics, giving us a common set of concepts with which to discuss whether a biochemical reaction or process is likely to occur, and if so in which direction and how fast. This will be critical as we begin to consider some of the key types of reactions that take place in metabolism.
- We have learned and practiced the energy story rubric. This too will allow us to systematically examine new biochemical reactions and processes and to discuss them with a common language and approach that is consistent and reinforces the lessons we learned about thermodynamics.
A brief overview of this section
- You will be introduced to an important concept called reduction potential and you will be given the opportunity to use a redox tower. There is also a discussion on redox chemistry in your discussion manual. Make sure to use both resources.
- You will be introduced to two major players in metabolism, ATP and NADH. You will be expected to recognize their structures if shown on an exam.
- The metabolic pathway glycolysis will be covered in detail. Keep in mind that we want you to be able to look at any reaction and tell us an energy story of that reaction. By no means should you spend time trying to memorize these pathways (though it will help tremendously to remember some big picture things - these will be stressed). Often we will give you the pathway as a figure on the exams. Glycolysis ultimately produces 2 ATP via a process called substrate level phosphorylation, 2 NADH and 2 pyruvate compounds.
- We will use the reactions of the TCA cycle to create multiple examples of energy stories. The TCA cycle will also produce more ATP, NADH and completely oxidize glucose into CO2.
- We will look at an alternative pathway to that of the TCA cycle, fermentation. In fermentation for the first time we will see NADH used as a reactant in a metabolic reaction.
- We will follow NADH to the end of its journey, as it donates its electrons to the electron transport chain (ETC). In this module you will need to be able to use a redox tower. The ETC produces a proton gradient. No ATP is directly generated in this process. However, the proton gradient is then used by the cell (among other things) to run an enzyme called ATP synthase which catalyzes the reaction ADP + Pi --> ATP. This method of ATP production (called oxidative respiration) results in much more ATP being produced than substrate level phosphorylation.
- And finally, we will go through the process of photosynthesis.