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a. changes in pH; and
b. increasing temperatures.
a. Enzymes arc sensitive to acidity or alkalinity of a solution. Some work best in acidic conditions, for example, pepsin in the stomach, whereas others work best in alkaline conditions, for example pancreatic amylase. Enzymes are proteins in nature. Extreme changes in pH denature the enzyme. When an enzyme is denatured, it loses its active site configuration and its biological activity thereby decreases.
b. Enzymes work best under optimum temperature, which is 37ºC for most enzymes found in our body. A high temperature increases the kinetic energy supplied to the reacting molecules, which then increases the rate of collision between substrates and enzymes. The rate of the reaction increases up to the optimum temperature. Beyond the optimum temperature, an enzyme, being protein in nature, will be denatured and will lose its active site configuration. The rate of biological reaction will therefore decrease.
2a. Describe the major properties of enzymes.
2b. Discuss the mode of action of an enzyme in terms of active site, enzyme-substrate complex, activation energy and enzyme specificity.
a. Enzymes are highly specific in action. They are mainly made up of proteins. Enzymes alter the rate of chemical reactions without themselves being changes at the end of the reaction. Small amounts of enzymes are capable of catalysing a large number of reactions. Enzymes work within a narrow range of conditions, such as they have an optimum working temperature and beyond a certain temperature, they are denatured. Enzymes are also affected by the acidity/alkalinity of the solutions in which they act.
b. An enzyme is a catalyst. It acts on a substrate and converts it into a product. The binding of a substrate to the active site of an enzyme is specific in nature. A substrate fits into an enzyme's active site like how a key fits into a lock, forming an enzyme-substrate complex. An enzyme lowers the activation energy needed for a reaction. Activation energy is the energy needed to start a chemical reaction.