Metabolism Notes BIOL 1406 02
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This 4 page Class Notes was uploaded by locnaschek on Tuesday September 20, 2016. The Class Notes belongs to BIOL 1406 02 at Lamar University taught by Dr. Randall Terry in Fall 2016. Since its upload, it has received 10 views. For similar materials see General Biology I (Majors) in Biology at Lamar University.
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Date Created: 09/20/16
Metabolism Metabolism is the sum total of all chemical reactions in a cell Two kinds: o Catabolism break down Used in hydrolysis Releases energy Breaks bonds Spontaneous, occurs naturally in the environment Reactants have more energy than products The difference of energy is what is released (negative) o Anabolism build up Used in dehydration synthesis Requires energy input Builds things up from building blocks, creates bonds Nonspontaneous, does not occur naturally Products have more energy than reactants The difference of energy is what is put in (positive) Two types of reactions discussed: o Exergonic Spontaneous, natural Catabolic Energy is released Reactants have more energy than products (“downhill” reaction) Difference of energy is what is released, negative o Endergonic Nonspontaneous, unnatural Anabolic Requires an energy input Products have more energy than reactants (“uphill” reaction) Difference of energy is what is put in, positive o Most of the energy released in an exergonic reaction is heat energy, but a small amount is free energy that can be of use for an endergonic Free energy is energy that is available to do work Exergonic reactions are always coupled with endergonic reactions because the energy released by exergonic drives endergonic reactions Adenosine Triphosphate (ATP) o Molecule used to carry out most cellular work o Energy currency of the cell o Made up of 3 phosphate groups and a sugar When a phosphate is removed, it results in an inorganic phosphate, Adenosine Diphosphate (ADP), and energy If another is removed, it is called Adenosine Monophosphate (AMP) and more energy is released Less energy is available each time a bond is broken o Endergonic reactions occur by giving a phosphate from ATP to a molecule which makes it more reactive so it can bond with another molecule Enzymes o Proteins that catalyze biochemical reactions o Reactions go through a “transition state” between reactants and products which requires a bit of energy (uphill part of the way) This energy is called EA or activation energy Heat energy inside the cell is enough to allow the transition state occur (breaks the bonds) The reactions then go as normal, forming new bonds and releasing energy o Enzymes can significantly lower the energy required for the transition state to occur which greatly speeds up the process This does not change the spontaneity of a reaction so if the reaction is endergonic enzymes will not change anything o Sucrose is a substrate, a molecule that binds to the active site of an enzyme The enzyme for sucrose is sucrose. It holds the substrate, brings in water, and breaks the bond of the substrate. The active site is where the substrate goes when it attaches to an enzyme An induced fit is when the enzyme forms itself to fit the substrate o Catalytic process: 1. The substrate binds to the enzyme 2. The substrate is broken down into products 3. Products are released 4. The active site of the enzyme is ready to accept another substrate and begin the process again o Factors that influence the rate of an enzyme catalyzed reaction Temperature Anything that influences protein shape Temperature pH Ion concentration Relative concentration Of enzymes Of substrates Binding strength of the enzymes and substrates o Regulation of Enzyme Activity Some amino acids cannot be made by the body and must be taken in This is how the cell knows whether to make an amino acid and which one Feedback Inhibition allows enzymes to stop or slow down the process of creating amino acids when necessary The Regulatory Site is where the end product of the feedback loop is bound; this changes the shape of the active site and stops it from binding to substrates which stops the reaction This process is not always on or off, it can be between (like 59% or 11% rather than 0% or 100%) o Mechanics of regulation Noncompetitive Inhibition Regulator binds to the regulation site, and a change in conformation occurs Competitiv Inhibition Inhibitor mimics the substrate and binds to the active site in place of it, does not require a change in conformation Allosteric Regulation quaternary structure More complex Includes enzymes with four subunits and thus four active sites Rapidly oscillates between active and inactive form o If an activator binds at a regulatory site, the enzyme stabilizes in the “on” form (active) o If an inhibitor binds at a regulatory site, the enzyme stabilizes in the “off” form (inactive) Cooperativity also quaternary If a substrate molecule binds to the enzyme when it is active, it stabilizes and allows it to create bonds with the other active sites Binding of a substrate molecule to the active site causes all subunits to take become active which amplifies enzyme activity Localizati of Enzymes Protein Targeting Controlling where enzymes are Temperature also regulates enzymes Reactions work best/fastest at their optimum temperature Too much heat provides too much movement which make it lose its shape Denaturation means it lost its shape and is not functional
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