Chapter 3 Lecture Quiz

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The enzyme-substrate complex is

Multiple Choice
another name for the active site.
the reactants whose chemical reaction the enzyme catalyzes.
the chemical structure formed when the substrate binds to the active site.
a pocket on the substrate that the enzyme recognizes.
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Terms in this set (23)
The enzyme-substrate complex is

Multiple Choice
another name for the active site.
the reactants whose chemical reaction the enzyme catalyzes.
the chemical structure formed when the substrate binds to the active site.
a pocket on the substrate that the enzyme recognizes.
the chemical structure formed when the substrate binds to the active site.
Which statement accurately describes the effects of substrate and enzyme concentrations on reaction rate?

Multiple Choice
An increase in either substrate or enzyme concentration will increase the reaction rate.
An increase in either substrate or enzyme concentration will decrease the reaction rate.
An increase in substrate concentration increases the reaction rate, but enzyme concentration has no effect.
A decrease in substrate concentration or an increase in enzyme concentration increases the reaction rate.
An increase in substrate concentration or a decrease in enzyme concentration will increase the reaction rate.
An increase in either substrate or enzyme concentration will increase the reaction rate.
The term "metabolism" refers to

Multiple Choice
reactions involving the breakdown of complex molecules into simpler ones.
reactions involving the breakdown of complex molecules or the exchange of atoms between similarly sized reactants.
all the chemical reactions in the body.
reactions involving the synthesis of complex molecules from simpler ones.
digestive system reactions that are either catabolic or exchange reactions.
all the chemical reactions in the body.
Lingual lipase is an enzyme with an optimum pH around 5. This is __________ than the optimum pH of most enzymes in the body.

Multiple Choice
lower
higher
lower The optimum pH for most body enzymes is between 6 and 8.
The optimum temperature for most enzymes is around body temperature. If the body temperature is slightly elevated, what effect will this have on enzymatic reactions?

Multiple Choice
Increased reaction rates
Stiffer, more rigid enzymes
Enzymes may denature
Less kinetic energy, so less likely for enzyme and substrate to contact
Increased reaction rates
The term "activation energy" refers to the amount of energy

Multiple Choice
released by an exergonic reaction.
released by an endergonic reaction.
released by a catabolic reaction.
required to initiate any chemical reaction.
required to initiate only catabolic reactions.
required to initiate any chemical reaction.
In the final step of enzymatic catalysis,

Multiple Choice
the substrate is released and the enzyme is inactivated.
the product is completed and the enzyme is inactivated.
the products are released and the enzyme is free to bind other substrates.
the enzyme and substrate form chemical bonds with each other resulting in a new product.
equilibrium is obtained so that the enzyme does not catalyze further reactions.
the products are released and the enzyme is free to bind other substrates.
A large decrease in pH results in increased H+ binding to an enzyme, which can disrupt electrostatic interactions within the molecule.

Group starts
True or False
true
The optimal pH range for most human enzymes is

Multiple Choice
1-2.
4-6.
6-8.
8-10.
13-14.
6-8.
The enzyme RNA polymerase is synthesized

Multiple Choice
at a ribosome, and it remains within the cell.
at the rough endoplasmic reticulum, and it is secreted from the cell.
at the Golgi apparatus, and it is embedded in the cell membrane.
in the nucleus, and it is converted to RNA for export outside the cell.
at a ribosome, and it remains within the cell.
At temperatures above 40°C (104°F) in the human body, Multiple Choice enzymatic reactions with substrates are more quickly catalyzed. enzymes denature and reaction rates decrease. protein flexibility is optimum and reaction rates increase. protein shape is rigid and reaction rates are constant.enzymes denature and reaction rates decrease.The optimal pH range for the stomach enzyme pepsin is Multiple Choice 2-4. 6-8. 7.3-7.4. 10-12. 12.0-13.5.2-4.Maltase is an enzyme that breaks down maltose. If a maltase enzyme has just completed catalyzing the decomposition of maltose, then Multiple Choice it is able to catalyze another reaction, but it must use a different active site. it is only able to catalyze a reaction with a different substrate, like lactose. it is available to catalyze the same reaction with another maltose molecule. it cannot catalyze another reaction.it is available to catalyze the same reaction with another maltose molecule. Enzymes are used to catalyze the same reaction over and over.Saturation occurs when Multiple Choice there is so much enzyme present that the reaction rate decreases if more is added. all enzymes are busy and further increases in substrate concentration will not increase reaction rate. enzymes become fatigued and can no longer catalyze changes in the substrate. intramolecular interactions are disrupted in the enzyme, decreasing its efficiency and decreasing reaction rate. the substrate is denatured and the enzyme cannot catalyze any changes in its structure.all enzymes are busy and further increases in substrate concentration will not increase reaction rate.As concentration of substrate is increased in a reaction catalyzed by an enzyme, the reaction rate will stop increasing once saturation is reached because Multiple Choice there are too many enzymes available and not enough substrate. once the enzymes react once, they cannot react again. all enzymes are actively engaged in a reaction. increasing substrate inhibits enzyme activity.all enzymes are actively engaged in a reaction. At or above saturation, the reaction rate is limited by enzyme concentration because there is so much substrate that each enzyme is busy catalyzing a reaction.The region of an enzyme into which the substrate fits is a Multiple Choice one-size-fits-all active site. highly specific active site. highly specific antibody. one-size-fits-all antibody.highly specific active site.The building of complex molecules from simpler ones is described as Multiple Choice anabolism. catabolism. exergonic. irreversible. reversible.anabolism.The presence of an enzyme within a chemical system Multiple Choice increases activation energy. decreases activation energy. increases potential energy. does not affect either activation energy or potential energy.decreases activation energy.Enzymes are Multiple Choice lipids. proteins. carbohydrates. nucleic acids. steroids.proteins.Which of the following binds to the active site of an enzyme? Multiple Choice Water Product Substrate Any other enzyme None of these choices are correct.SubstrateWhich of the following correctly represents the mechanism of enzyme function? E = enzyme S = substrate P = product Multiple Choice S + P -> E-P -> E + P E + P -> E-P -> E-S -> E + S E + P -> E-S -> E-P -> E + P E + S -> E-S -> E-P -> E + P E + S -> E-P -> E-S -> E + SE + S -> E-S -> E-P -> E + PAn enzyme speeds up a chemical reaction in the cell, but can only be used once. Group starts True or FalsefalseAn enzyme can only bind one reactant at a time. Group starts True or Falsefalse