Human Physiology
15th Edition
ISBN: 9781259864629
Author: Fox, Stuart Ira
Publisher: Mcgraw-hill Education,
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Textbook Question
Chapter 4, Problem 2RA
Which of these statements about enzyme-catalyzed reactions is true?
a. The
b. The rate of all enzyme-catalyzed reactions is decreased when the pH is lowered from 7 to 2.
c. The rate of reaction is independent of substrate concentration.
d. Under given conditions of substrate concentration, pH, and temperature, the rate of product formation varies directly with enzyme concentration up to a maximum, at which point the rate cannot be increased further.
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Students have asked these similar questions
Please choose one of these answers
A. An allosteric inhibitor appeared
B. There was a dramatic change jn the pH.
C. The enzyme had achieved its maximum velocity.
D. The enzyme had denatured
E. A large amount of the substrate had been consumed.
Consider the following enzyme cartoons or structures carefully. Note active sites, presence of
cofactors, substrates, etc. and then answer the following questions with the applicable
numbers 1, 2, 3, 4, None or All. More than one number may apply.
3.
2.
1.
GO
Substrate
Enzyme
Substrate
Enzyme
Pepsin
Enolase
a. Example(s) of an allosteric enzyme
b. Example(s) of a proteolytic enzyme
c. Example(s) of an enzyme(s) with cofactor(s)
e. Example(s) of an enzyme(s) that could be impacted by an irreversible
competitor.
d. Example(s) of an enzyme(s) with a second site for feedback control.
f. Enzyme(s) definitely composed of two or more protein chains.
Consider the Michaelis-Menten enzymes below and answer the following questions.
Kcat (s')
9.5*105 1.4*10*
2.5*102 1.0*107
5.0*10 8.0*10²
Enzyme Km (M)
A
В
a. Which enzyme has the highest affinity substrate? How do you know?
b. Which enzyme can convert the most substrate to product in a given period of time? How
do you know?
c. Which enzyme has the highest catalytic efficiency? How do you know?
Chapter 4 Solutions
Human Physiology
Ch. 4 - Use the lock-and-key model to explain how enzymes...Ch. 4 - Explain how enzymes are named, and the nature of...Ch. 4 - Draw graphs to represent the effects of changes in...Ch. 4 - Prob. 4CPCh. 4 - Prob. 5aCPCh. 4 - Prob. 5bCPCh. 4 - Prob. 5cCPCh. 4 - Prob. 6aCPCh. 4 - Define the terms exergonic reaction and endergonic...Ch. 4 - Prob. 7aCP
Ch. 4 - Prob. 7bCPCh. 4 - Which of these statements about enzymes is...Ch. 4 - Which of these statements about enzyme-catalyzed...Ch. 4 - Which of these statements about lactate...Ch. 4 - In a metabolic pathway, a. the product of one...Ch. 4 - In an inborn error of metabolism,
a. a genetic...Ch. 4 - Which of these represents an endergonic...Ch. 4 - Which of these statements about ATP is true? a....Ch. 4 - When oxygen is combined with 2 hydrogens to make...Ch. 4 - Enzymes increase the rate of chemical reactions...Ch. 4 - According to the law of mass action, which of...Ch. 4 - Explain the relationship between an enzyme's...Ch. 4 - Explain how the rate of enzymatic reactions may be...Ch. 4 - Explain how end-product inhibition represents a...Ch. 4 - Prob. 14RACh. 4 - The coenzymes NAD and FAD can "shuttle" hydrogens...Ch. 4 - Prob. 16RACh. 4 - Why do we need to eat food containing niacin and...Ch. 4 - Metabolic pathways can be likened to intersecting...Ch. 4 - Prob. 19RACh. 4 - Suppose you come across a bottle of enzyme tablets...Ch. 4 - Describe the energy transformations that occur...Ch. 4 - Use the reversible reactions involving the...Ch. 4 - Use the graph here and in figure 4.4 to answer the...Ch. 4 - Use the graph here and in figure 4.4 to answer the...Ch. 4 - Prob. 25RACh. 4 - Prob. 26RACh. 4 - Prob. 27RA
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- Which of the following will happen if the concentration of an enzyme increases for a given substrate?? a. the reaction rate increases similarly b. the rate of the reaction decreases to a point. c. there is no change in the reaction. d. the turnover number decreases at the same rate that the enzyme concentration increases. e. the reaction stops.arrow_forwardEvaluate the following statements concerning enzyme kinetics. Which one of the statements is false? a. Enzyme saturation fluctuates. b. In an uninhibited enzymatic reaction system, adding an excess of substrate will increase the reaction velocity beyond Vmax. c. The Vmax of an enzyme kinetics graph represents the point at which the enzyme is saturated with substrate. d. Non-competitive inhibition of an enzymatic reaction can be overcome by adding more unaltered enzyme. e. The activation energy of a reaction can be reduced by the presence of an enzyme.arrow_forwardWhich of the following statements about the Michaelis Menten constant (Km) is correct......A. can be determined by plotting the data v/[S] against 1/[S] B. A large Km indicates a low affinity between the enzyme and the substrate C. A large Km means that a large concentration of substrate is needed for the enzyme to work D. is a measure of the affinity of enzymes for proteins, minerals and vitamins E. Small Km means that a large concentration of substrate is needed for the enzyme to workarrow_forward
- Sucrase has an optimum temperature of 37°C and an optimum pH of 6.2. Determine the effect of the following on its rate of reaction: 1) no change 2) increase decrease 3) A. increasing the concentration of sucrase B. changing the pH to 4.0 C. running the reaction at 70°C What are the functions of Allosteric enzymes What are some factors that affects enzyme activity? I. II. III. IV. V. VI. Enzyme activity can be regulated by allosteric enzymes, feedback control, and covalent modifications. T/F Examples of Zymogens are the proteases trypsinogen and chymotrypsinogen. T/F? Trypsin catalyzes the removal of dipeptides from inactive chymotrypsinogen and trypsinogen to give the active proteases chymotrypsin and trypsin. T/F The removal of a polypeptide chain from proinsulin produces the active form of insulin. T/F? A kinase can activate an inactive enzyme by phosphorylation, ie adding a phosphate group. T/F? A phosphatase can activate an inactive enzyme by removal of phosphate. T/F? Identify…arrow_forwardFoF1 ATPase is the enzyme that catalyzes ATP synthesis. The enzyme itself is deactivated by ATP. What mode of enzyme regulation is being exemplified? Select the correct response: Trasncriptional control Covalent modification Proteolytic modification Allosteric regulation Compartmentationarrow_forwardWhich of the following statement on the process of enzyme production is false? Select one: a. Agglomeration is sometimes used to increase solubility of enzyme powder b. After fermentation, intracellular enzymes can be directly extracted by filtration c. Spray drying can be used to dry the enzyme products into powder forms d. Chromatography is used to purify the enzyme producedarrow_forward
- a. What is the name of metabolite 1? b. What is the name of metabolite 2? c. What kind of reaction occurred when 1 was converted to 2? d. What general kind of enzyme might you expect to perform this reaction? e. What cofactor, if any, would be required for this reaction?arrow_forwardIndicate whether each of the following statements about an enzyme active site is true or false. a. It is the location where substrate molecules are produced. b. It always has a fixed, rigid geometry. c. It always has a geometrical shape exactly complementary to that of substrate. d. It always accomodates several structurally related substrates. e. It is the location where substrate molecules are converted to product molecules. f. It always has a shape that has a degree of flexibility to it. g. it always accomodates only one specific substrate.arrow_forwardWhat is a limitation of the Michaelis-Menten kinetics? A. Enzymes have different binding sites which were not considered by the Michaelis-Menten assumption. B. Most enzymes are multimeric with many active sites. C. Variability in enzyme concentration due to synthesis and degradation by cells were not included in the Michaelis- Menten assumption. D. Enzymes have coenzymes that are involved in catalysis. E. Active sites can bind multiple substrates.arrow_forward
- a. Provide a name for both metabolites. b. What kind of reaction occurs here? c. What enzyme performs this reaction? d. What cofactors (if any) are involved in this reaction? e. Thermodynamically, this reaction is unfavorable. What allows for this reaction to proceed in the cell? **pls help me with this homework question!!** these questions pertain to the image attachedarrow_forwardWhich one of the following statements is true of enzyme catalysts? a. Their catalytic activity is independent of pH. b. They are generally equally active on D and L isomers of a given substrate. c. They can increase the equilibrium constant for a given reaction by a thousand fold or more. d. They can increase the reaction rate for a given reaction by a thousand fold or more. e. To be effective, they must be present at the same concentration as their substrate.arrow_forwardSketch and label a plot showing the enzyme's initial velocity relative to pH over the pH range 4 - 9 for the enzyme-catalyzed reaction under these two conditions: A. The substrate concentration is very, very high. B. The substrate concentration is less than the enzyme's Km.arrow_forward
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Enzyme Kinetics; Author: MIT OpenCourseWare;https://www.youtube.com/watch?v=FXWZr3mscUo;License: Standard Youtube License