Describe two factors which may increase enzyme activity and two factors which may decrease enzyme activity. Explain how each factor works to increase or decrease enzyme activity, and identify whether that factor is used internally by the cell (i.e. for
regulation of a chemical reaction) or acts externally (i.e. is a component of the environment or a human-influenced component).
What will be an ideal response?
The following factors may influence enzyme activity. 1 ) Cofactors/coenzymes are non-protein chemicals associated with certain enzymes and are necessary for enzyme function. They are cellular components and function internally. 2 ) Temperature is an environmental factor working externally to the cell. Increasing temperature up to the optimum will increase enzyme activity, but temperatures hotter than optimum will lead to a rapid decline in enzyme function as the enzyme denatures, or loses its shape. 3 ) An environmental pH value more acidic or more basic than the optimum pH of the enzyme will lead to a decline in enzyme activity due to changes to the enzyme's shape. 4 ) Enzyme activity will increase with increasing enzyme concentration relative to the substrate concentration. As substrate concentration increases, a saturation point will be reached where all enzymes are occupied by a substrate. Cells can regulate the amount of enzyme up or down to accommodate its need for a given product. 5 ) Cells can reversibly activate or deactivate enzymes based on need by adding or removing phosphate groups to the enzyme. 6 ) Competitive inhibitors are molecules that directly compete with the substrate to bind at the enzyme active site, thereby decreasing enzyme activities. Noncompetitive inhibitors interact with an enzyme at some location other than the active site, but decrease enzyme activity. Many pharmaceuticals, poisons, and toxins act as either competitive or non-competitive inhibitors. 7 ) Allosteric regulators bind with enzymes at a specific location called the allosteric site and may either activate or inhibit enzyme activity. This is often used by cells as an internal means of regulation.
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