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Oxidation and Reduction – Oxidation and Reduction in Metabolism

by Kevin Ahern, PhD
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    00:01 Now so delta G is a very, very valuable term for us to understand direction that happens within a cell and as I said these values are actually additive. Well how does this come into consideration and why is it important to think about? Well every reaction that occurs in cell is related to energy and the most important reactions that cells undergo in terms of energy are those involved in oxidation and reduction, because oxidative reactions will tend to release energy that the cells can use for purposes and reductive reactions will tend to require an input of energy. Now as we will see later when we talk about metabolism, these are very important considerations, because one set of metabolic pathways will be oxidative in nature and another set will be reductive in nature. What do we mean when we say reduction and oxidation? Let's take the example of ethanol shown at the very top. Ethanol has around its central carbon, including the electrons around the oxygen and the hydrogen, a total of twelve electrons. If we convert ethanol into acetaldehyde, we've converted an alcohol into an aldehyde, and anybody from organic chemistry knows that's an oxidation.

    01:14 Well what does that oxidation mean in terms of electrons? Well if we draw the structure of acetaldehyde with the electrons around it, we see that it has ten electrons around it, around the carbon of interest, whereas ethanol had twelve. That means that the molecule has lost two electrons. The loss of electrons is what happens in oxidation and we can see this in this equation here that we have acetaldehyde plus two electrons released and two protons released. These commonly happen in biological oxidations. If we took the reaction backwards, we could add two electrons and two protons to acetaldehyde and we would create ethanol, that's a reduction. So oxidation refers to the loss of electrons and reduction refers to the gain of electrons. Now while these are usually accompanied by protons, we don't usually include the protons in the description. So if we just keep in mind the electrons, then we will be able to remember what oxidation and reduction are all about.

    02:15 Now it turns out that electrons are really, really reactive, they cause chaos if they're simply released as such and cells don't do very well with chaos. Now it's important then that cells have a way of managing that chaos and as I like to say, cells are pretty big control freaks. They're control freaks because they really handle things as much as they can, whether it's enzymes controlling reactions, or in this case, the cells controlling the release of electrons


    About the Lecture

    The lecture Oxidation and Reduction – Oxidation and Reduction in Metabolism by Kevin Ahern, PhD is from the course Biochemistry: Basics.


    Included Quiz Questions

    1. It involves a loss of electrons
    2. It requires oxygen
    3. It usually requires an input of energy
    4. It requires NADH

    Author of lecture Oxidation and Reduction – Oxidation and Reduction in Metabolism

     Kevin Ahern, PhD

    Kevin Ahern, PhD


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