Enzymes Flashcards
Define the term “activation energy.”
The amount of energy that reactants must absorb before a chemical reaction will start. Also its energy barrier protects the highly ordered molecules of your cells from spontaneously breaking down.
Explain how enzymes speed up chemical reactions.
All enzyme speeds up a reaction by lowering the Ea needed for a reaction to begin.
Outline several types of chemical reactions catalyzed by enzymes
Catabolism: hydrolysis- breaking things down
anabolism: dehydration synthesis- putting things back together
Contrast catabolism and anabolism.
Anabolic reactions assemble macromolecules from simpler ones, usually requiring a net input of energy to join the monomers. Anabolic reactions are used to assemble starches & proteins.
Catabolic reaction breaks down complex molecules for a net release of energy, which is usually used for other things.
Describe the catalytic cycle.
Enzyme + substrate gives an enzyme - substrate complex and then free enzyme + products.The enzyme now repeats this cycle again and again.
Explain the induced fit model of enzyme-substrate interactions.
The Induced fit model describes the formation of the Enzyme-Substrate as a result of the interaction between the substrate and a flexible active site. The substrate produces changes in the conformation on the enzyme, aligning properly the groups in the enzyme. It allows better binding and catalytic effects.
Explain how pH, temperature and enzyme/substrate concentrations affect enzyme activity.
Higher Temperature or higher pH will cause the enzyme to change its shape. Since all proteins are known to have a specific function based on their shape, the enzyme will be denatured and no longer work. a point is reached when the reaction rate decreases with increasing temperature. At high temperatures the protein part of the enzyme begins to denature, thus inhibiting the reaction. As the pH is decreased or increased, the nature of the various acid and amine groups on side chains is altered with resulting changes in the overall shape structure of the enzyme.
Outline the importance of cofactors/coenzymes
A cofactor is needed for the proper functioning of an enzyme, and a coenzyme is a type of cofactor that is mainly used as vitamins in important metabolic reactions.
Explain how competitive and noncompetitive inhibitors alter an enzyme’s activity.
A competitive inhibitor is a substance that reduces the activity of an enzyme by binding to the enzyme’s active site in place of the substrate. A competitive inhibitor’s structure mimics that of the enzyme’s substrate. A noncompetitive inhibitor is a substance that reduces the activity of an enzyme without entering an active site. By binding elsewhere on the enzyme, a competitive inhibitor changes the shape of the enzyme so that the active site no longer effectively catalyzes the conversion of substrate or product
Explain feedback inhibition.
A method of metabolic control in which a product of a metabolic pathway acts as an inhibitor of an enzyme without that pathway. A substrate is connected to the active site of an enzyme which then releases the product that is shaped differently than its original shape, this is repeated for a while onto the next few enzymes. After the final product is released, that product (which was the original substrate) travels back to the first enzyme and is used as a noncompetitive enzyme to stop from anymore chemical reactions to occur and therefore stop the process.
Explain how certain poisons, pesticides, and drugs inhibit enzymes
They act as inhibitors to prevent any more catalyzation of the enzymes and the substrate in order to reduce the pain
Substrate
A specific substance (reactant) on which an enzyme acts. Each enzyme recognizes only the specific substrate or substrates of the reaction it catalyzes. It is also a surface in or which an organism lives
Active site
The part of an enzyme molecule where a substrate molecule attaches (by means of weak chemical bonds). Typically a pocket or groove on the enzyme’s surface
