Bio Exam 3 Ch.8 Questions
Explain how substrate concentration affects the rate of an enzyme-controlled reaction.
Substrate concentration affects the rate of an enzyme-controlled reaction by the more substrate there is, the more frequently they can access the active sites of the enzyme. There is a limit to how fast the reaction can happen by adding more substrate. At one point, the concentration will be high enough that all the enzymes have their active sites occupied. This concentration is said to be saturated, and the rate of the reaction is determined by the speed at which the active site converts substrate to product.
Describe the function of enzymes in biological systems.
The function of enzymes in biological systems are to act as a catalyst to speed up chemical reactions in metabolism. Without the regulation by enzymes, chemical traffic trough the pathways of metabolism would become terribly congested because many chemical reactions would take such a long time.
Explain the induced-fit model of enzyme function and describe the catalytic cycle of an enzyme.
The induced-fit model of enzyme functions is caused by the substrate when it enters, it is the change in shape of the active site of an enzyme so that it fits more snugly to the substrate. The catalytic cycle of an enzyme is that the substrate binds to the active site of the Enzyme and by lowering the activation energy barrier.
Explain how the location of enzymes in a cell influences metabolism. Explain why compartmentalization is important in eukaryotic cells.
The location of enzymes in a cell influences metabolism because they have fixed locations within the cell and act as structural components of particular membranes. Compartmentalization is important in eukaryotic cells because they have organelles and these organelles need to carry out specific functions for the cell.
Explain the relationship between enzyme structure and enzyme specificity.
The relationship between enzyme structure and enzyme specificity is that the specificity of an enzyme results from its shape, which is a consequence of its amino acid sequence.
Explain how enzyme activity can be regulated or controlled by environmental factors, co-factors, and enzyme inhibitors
Enzyme activity can be regulated by temperature and pH. With temperature, the rate of an enzymatic reaction increases with increasing temperature. Each enzyme has an optimal temperature at which its reaction rate is greatest. With pH, enzymes also have an optimal pH at which it is most active. The optimal pH values for most enzymes are 6-8. For both factors, if it passes the optimal value, the protein will denature. Cofactors are required for catalytic activity. Cofactors are any nonprotein molecule or ion that is required for the proper functioning of an enzyme. There are two types of enzyme inhibitors, one which binds to the active site and blocks cataylysis (competitive inhibitors) and one that binds at the allosteric site and causes a conformational change. (non-competitive inhibitors).
Describe several mechanisms by which enzymes lower activation energy.
Enzymes lower activation energy by orienting substrates correctly, straining substrate bonds, providing a favorable microenvironment, and covalently bonding to the substrate.
Explain how metabolic pathways are regulated.
Metabolic pathways are regulated by controlling enzyme activity. The binding of an activator to a regulatory site keeps the shape that has functional active sites while the binding of an inhibitor keeps the inactive form. Cooperativity is the binding of one substrate increases the binding of subsequent substrates. Feedback inhibition is when the end product inhibits an early step in a biochemical pathway.
