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Chapter 6 Blog: An Introduction to Energy, Enzymes, and Metabolism (Ambika)

Page history last edited by Ambika Sharma 13 years, 6 months ago

In the first section of this page, you will write a daily summary of that day's class.  For example in  your chapter 2 blog, your first entry should be titled 9/3/10.  You should then write a one or two paragraph summary of that day's lecture, outlining the major points.  In the second section, you are required to add two items (link to a website, video, animation, student-created slide show, student-created PowerPoint presentation) and one journal article pertaining to a topic in this chapter.  A one-paragraph summary must accompany each item describing the main idea and how it applies to the lecture topic.  Please see the PBWorks help guide for assistance embedding video and other items directly in the page.  I will also produce a how-to video on using tables to wrap text around items and other useful tips.  Please see the syllabus for organization and grading details.


A.  Daily Blog




Today in class we discussed ENERGY. Energy is the ability to do work. There are two types of energy: kinetic energy and potential energy. Kinetic energy is the energy of motion. Potential energy, on the other hand, is stored energy. Dr. Weber used the example of the rubberband to show what potential energy is again. This time, however, in front of Yianni's face...Dr. Weber, you should have took my advice and flung it at him ;o) Next, we reviewed the first two laws of thermodynamics. The first law states that energy cannot be created or destroyed and energy can be transformed into different kinds of energy. The second law states that the transfer or transformation of energy from one form to another invreases entropy (disorder).The last thing we did in class was extremely helpful. We focused in on the equation: ΔG = ΔGproducts - ΔGreactants This equation allows us to find out what type of reaction is occuring, an endergonic or an exergonic reaction. Endergonic reactions are easily thought of as uphill reactions since they need energy (not spontaneous). Exergonic, on the other hand, are commonly thought of as downhill reactions because they release energy (spontaneous). In order to tell what the reaction is by looking at the free energy. If the free energy is positive, its endergonic. If the free energy is negative, its exergonic.




Today we discussed activation energy. Activation energy is the amount of energy required to cause a reaction to occur. Activation energy usually requires a lot of high energy to take place, thus making the process very long. Enzymes, however, are able to destabilize the bonds making the reaction quicker without consuming much energy. Dr. Weber gave us a wonderful example of breaking a marker. Breaking a marker by itself would take a lot of effort and energy (the reaction without enzymes). However, if he sawed it partially before coming to class, he would be able to break it with ease, without a lot of energy (the reaction with the help of enzymes). I love Dr. Weber's examples :o) ...BACK TO BUSINESS! We also discussed Vmax and KmVmax is the full capacity of a reaction while Km is half of the normal capacity of a reaction. Another topic we covered was inhibition. Inhibition is how an enzyme is not able to continuously create products. There are two types of inhibition: competitive inhibition and noncompetitive inhibition. Competitive inhibitors bind to the active site of the enzyme. While noncompetitive inhibitors bind to the allosteric region of the enzyme, changing its shape.





B.  Useful Materials




This video is about activation energy. Activation energy is the amount of energy required to cause a reaction to occur. This video gives a great explanation for what both exergonic and endergonic reactions are. More specifically, what the difference is between them.

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This image shows the difference between endergonic and exergonic reactions. As you can see in endergonic reactions the reaction is uphill so it requires energy, making them not spontaneous. In exergonic reactions, on the other hand, the reaction is downhill as it releases energy, making it spontaneous.




This article explains the function of cysteine S-conjugate B-lyases. These two enzymes convert cysteine S-conjugates to ammonium and sulfur containing fragments (RSH) as well as selenium Se-conjugate to selenium containing fragments (RSeH). These enzymes are important in amino acid metabolism. RSH is involved in toxification of drugs and halogenated alkenes.
Article: http://www.ncbi.nlm.nih.gov/pubmed/20949433


The activation of energy is the energy required to start a reaction.  Enzymes only lower the activation energy; they DO NOT effect the energy of the products and reactants.  The lower the activation of energy by either straining bond of compounds or bringing molecules close together.  Substrates bind to enzymes at the active site of the enzyme.  The reaction takes place at the active site.  Enzyme reaction has a maximum velocity.  The reaction reaches maximum velocity (Vmax) when it is saturated.  Saturation occurs when nearly all active sites are occupied by the substrate.  At this point, the velocity remains constant. The Km is the amount of substance required to bind to half the enzymes.  Enzyme reaction can be effected by inhibition.  There are two types of inhibitors: competitive and noncompetitive.  Competitive inhibitors bind to the active site of the enzyme.  Because of competitive inhibitors, the reaction requires more substrate to reach Km.  Noncompetitive inhibitors bind to the allosteric region of the enzyme, changing its shape.  This lowers the Km of the reaction, therefore it never reached the Vmax.


Comments (1)

Derek Weber said

at 3:47 am on Oct 26, 2010

A bit confused by the videos here. Why are there functional groups and bonding here?

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