38 Questions
Which type of enzyme inhibition occurs when the inhibitor binds to the enzyme-substrate complex?
Uncompetitive inhibition
In uncompetitive inhibition, is the Vmax lower or higher in the presence of the inhibitor?
Lower
Does the affinity of the enzyme appear to go up or down in the presence of the uncompetitive inhibitor?
Go up
Which type of enzyme inhibition occurs when the inhibitor can bind to both the enzyme and the enzyme-substrate complex?
Competitive inhibition
In competitive inhibition, is the Vmax lower or higher in the presence of the inhibitor?
Lower
Does the affinity of the enzyme appear to go up or down in the presence of the competitive inhibitor?
Go down
Which type of enzyme inhibition occurs when the inhibitor can bind to both the enzyme and the enzyme-substrate complex, but at different binding sites?
Noncompetitive inhibition
In noncompetitive inhibition, is the Vmax lower or higher in the presence of the inhibitor?
Lower
Does the affinity of the enzyme appear to go up or down in the presence of the noncompetitive inhibitor?
Go down
Which type of enzyme inhibition occurs when the inhibitor forms a covalent bond with the active site of the enzyme?
Irreversible inhibition
Which of the following is true about Michaelis-Menten kinetics?
It applies to both first order and zero order reactions
What is the role of glucokinase in the liver?
It catalyzes the conversion of glucose to glucose-6-phosphate
What is the difference between glucokinase and hexokinase in terms of Vmax?
Glucokinase has a higher Km than hexokinase
What is the difference between glucokinase and hexokinase in terms of Km?
Glucokinase has a lower Km than hexokinase
What is the purpose of a Lineweaver-Burk plot?
To determine the Km and Vmax of an enzyme
Which of the following is an example of reversible enzyme inhibition?
Competitive inhibition
What is the graph of an allosteric enzyme in the presence of an inhibitor?
A sigmoidal curve
What is the ratio that determines enzyme efficiency?
Kcat/Km
Which of the following is true about first order reactions?
Their reaction rate depends on the concentration of reactants
Which of the following is true about zero order reactions?
They have a constant reaction rate
Which enzyme is active even during fasting?
Hexokinase
What enzyme doesn't become active until after a high-carbohydrate meal?
Glucokinase
What is the main role of glucokinase and hexokinase?
Both glycolysis and glycogenesis
What does a higher Km tell you about the affinity of glucokinase for glucose, compared to the affinity of hexokinase for glucose?
Hexokinase has higher affinity
What pathway does hexokinase feed into if it can't do glycogenesis?
Glycolysis
Why is hexokinase inhibited by glucose-6-P, but glucokinase is not?
Hexokinase is allosterically inhibited by glucose-6-P
What is the general purpose of very efficient enzymes?
To convert substrates into products rapidly
Which is a more efficient enzyme: one with a larger or smaller value for Kcat/Km?
Larger value for Kcat/Km
What are some applications of enzyme inhibition?
Preventing the spread of cancer cells
What type of reversible inhibition is exemplified by methotrexate?
Competitive inhibition
Which of the following is an example of enzyme regulation via reversible covalent modification?
Phosphorylation of glycogen synthase inhibits glycogenesis
Which of the following is FALSE regarding enzymes?
The enzyme is used up by the reaction and will need to be remade via transcription and translation
Which of the following is an example of enzyme regulation via irreversible covalent modification?
Cleavage of a peptide bond in a proenzyme to form an active enzyme
What kind of bonds form the primary structure of a protein?
Peptide bond
When a heavy metal such as lead (Pb+2) interacts with bonds within a protein, it can denature the protein. Which of the following bonds are vulnerable to this type of denaturation?
Disulfide bridge
What important piece of information can be gained from Michaelis Menten kinetics?
The affinity of an enzyme for its coenzyme
Which of the following characteristics indicates the highest enzyme efficiency?
High Kcat, Low Km
Which of the following is true of any pseudo-first order reaction?
One substrate has a concentration is excess of what is needed
This quiz on Enzymes Part 2 Kinetics covers objectives such as defining Km and Vmax, understanding first order, pseudo-first order, and zero order reactions, and identifying specific enzymes. Test your knowledge on enzyme kinetics with Dr. Heisel's BMS100 quiz.
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