Biochemical Pathways

by Georgina Cornwall, PhD

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    00:00 So all of these comes together in biochemical pathways.

    00:06 So why are we exploring all these enzymes and why that we spend all this time looking at thermodynamics? Not because I really want to confuse you but they are important principals to understand in order to get a grip on how biochemical pathways can work and be regulated.

    00:24 All the biochemical pathways are considered our metabolism. We will be spending some time looking at the process of cellular respiration in brief because really it's the content of biochemistry to look at the extreme details of it but we'll recap some of the main points as they relate to biology.

    00:42 Before we do, we need to understand what biochemical pathways involve.

    00:48 They usually involve a sequence of enzymes such that we have a substrate that binds into the first enzyme in the pathway and it comes out transformed into a different molecule or cut into two pieces or however that enzyme functions.

    01:03 And that goes into the next enzyme and that enzyme does something to the substrate and turns it into a different product and then that product becomes the substrate for the next enzyme and so on and so forth until eventually we get an end product in the biochemical pathway.

    01:20 Now the neat thing about this is sometimes these biochemical pathways regulate themselves in the mechanism of negative feedback.

    01:29 I believe that I've introduced you the negative feedback before but here's a real life example.

    01:34 We have our protein, enzyme, taking a molecule that's a substrate, changing it, changing it, changing it.

    01:41 We move down the pathway, we eventually get our end product And that very end product could, guess what, come back and be an allosteric inhibitor for an enzyme earlier in the pathway.

    01:55 Once it ... , could be a competitive inhibitor.

    01:59 Either way, it's going to shut the active site, so the active site doesn't work properly and therefore the substrate cannot binds to that enzyme and the production of the product is shut down.

    02:13 So a great example of negative feedback.

    02:17 So in this lecture, I've introduced you to some foundational concepts that are going to help us understand the specifics of cellular respiration.

    02:28 We should now be able to define the laws of thermodynamics as they apply to free energy, recall free energy is the energy available to do stuff in our cells.

    02:39 We may increase free energy in reactions or decrease free energy in reactions.

    02:44 In addition, you should be able now to explain the roles of enzymes in lowering activation energy in biochemical pathways, which we call metabolism.

    02:56 Thank you so much for your attention. I look forward to taking you on the rest of the tour through the metabolic processes.

    About the Lecture

    The lecture Biochemical Pathways by Georgina Cornwall, PhD is from the course Energy, Enzymes and Metabolism.

    Included Quiz Questions

    1. A series of enzymatic reactions that convert a substrate into a product that can be utilized in a biological system
    2. A mechanism by which the product of an enzyme will feedback and inhibit the original enzymatic step
    3. A mechanism by which a molecule assists an enzyme to convert a substrate into a product
    4. A mechanism by which a molecule inhibits enzymatic activity when it binds to the active site of the enzyme
    5. The mechanism by which food is chemically and mechanically broken down
    1. Metabolism - chemical reactions taking place in the core of the sun to produce sunlight
    2. Enzymes – biocatalysts
    3. ATP – cellular energy currency
    4. Catabolism – breakdown of complex molecules into simple ones
    5. Anabolism – synthesis of complex molecules from simple ones

    Author of lecture Biochemical Pathways

     Georgina Cornwall, PhD

    Georgina Cornwall, PhD

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