B.7.1 Describe the characteristics of• Enzymes are protein molecules that act as catalysts for biological reactions.• The enzymes are highly specific for each reaction and are very efficient.• The enzymes are highly specific because of their tertiary and quaternary structures.• The active site is the part of the enzyme that reacts with the substrate.
B.7.2 Compare inorganic catalysts and Biological Catalysts both types of catalysts Inorganic CatalystsThey are specific to the The catalysts provide an They are not specific toreaction. alternative path for the the reaction. reaction with a lowerThey are proteins, like They increase the rate of They can be anything. activation energy.amino acids. the reaction.They are specific to They can be applied tohuman bodies and life. other situations.
B.7.3 Describe the relationship betweensubstrate concentration and enzyme activity.• As the concentration of the substrate increases the rate of the reaction increases, when the concentration is low there are enough active sites but the rate of reaction is lower.• Higher concentrations have a higher rate of reaction, but when the rate reaches a certain point (Vmax) it peaks. At this point all of the active sites are used and the rate cannot be increased any more.
B.7.4 Determine Vmax and the value of the Michaelis constant (km)by graphical means and explain its significance. Vmax is impossible to attain in an enzyme reaction so we use half of vmax to characterize a specific enzyme reaction. To determine vmax you find the point at which the graph is parallel to the x-axis. To determine the Michaelis constant divide vmax by two and find that y-value on the graph, the corresponding x value is the Michaelis constant. The Michaelis constant and half of vmax help to identify an enzyme reaction and to determine what concentration of the substrate should be used to get the desired concentration.
B.7.5 Describe the mechanism of enzyme action, includingenzyme substrate complex, active site and induced fit model. The active site is the part of the enzyme that reacts with the substrate. It is formed by the tertiary or quaternary structure of the enzyme. The active site on the enzyme is a groove that can change its shape to fit the substrate.
B.7.6 – Compare competitive inhibition• Inhibitors: substances that slow down the rate of enzyme- catalyzed reactions• Competitive Inhibitors: • Have a similar structure to the substrate and occupy the active site on the enzyme • Increasing the substrate concentration will lessen the effect of the competitive inhibitors • Vmax of the reaction does not change, but Km increases.
•Non-competitive Inhibitors: • Bind to the enzyme but not at the active site • Causes the enzyme to change its shape so that the substrate cannot bind to the enzyme • Increasing the substrate concentration will not change the effect of non-competitive inhibitors • Vmax but Km will stay the same.•The effects of both inhibitors are reversible.
B.7.7 – State and explain the effects of heavy metal ions,• Metal Ions:• Can poison enzymes by reacting with -SH groups replacing the hydrogen atom with a heavy metal atom or ion so that the tertiary structure is altered.• Temperature:• Increasing the temperature will increase the rate of enzyme- catalyzed reactions to a certain point. Enzymes have an optimal temperature where they will work best. After this point, the enzymes denature.• pH:• At the enzymes, optimal pH, the reaction will occur fastest with the enzyme present. However, at different pH levels, the charges on the amino acid residues change, affecting the bonds between them. The enzyme denatures.