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Ch.10 Proteins Workers of the Cell
Frost - General, Organic and Biological Chemistry 4th Edition
Frost4th EditionGeneral, Organic and Biological ChemistryISBN: 9780134988696Not the one you use?Change textbook
All textbooksFrost 4th EditionCh.10 Proteins Workers of the CellProblem 53a
Chapter 6, Problem 53a

The enzyme urease functions in the body to catalyze the formation of ammonia and carbon dioxide from urea as shown:
Chemical reaction showing urease catalyzing urea and water into ammonia and carbon dioxide.
Describe what effect the following changes would have on the rate of this reaction assuming a steady state has been reached:
a. adding excess urea

Verified step by step guidance
1
Understand the role of urease: Urease is an enzyme that catalyzes the breakdown of urea into ammonia and carbon dioxide. Enzymes speed up reactions by lowering the activation energy required for the reaction to occur.
Recognize the concept of steady state: In a steady state, the reaction rate is constant because the enzyme is working at its maximum capacity, and the concentration of reactants and products remains stable over time.
Consider the effect of adding excess urea: Adding more urea increases the substrate concentration. Initially, this may increase the reaction rate as more substrate molecules are available for the enzyme to act upon.
Understand enzyme saturation: If the enzyme is already saturated (all active sites are occupied), adding excess urea will not further increase the reaction rate. The enzyme can only process a certain amount of substrate at a time.
Conclude the effect: At steady state, adding excess urea will have little to no effect on the reaction rate if the enzyme is already saturated. However, if the enzyme is not saturated, the reaction rate may increase until saturation is reached.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Enzyme Catalysis

Enzymes are biological catalysts that speed up chemical reactions by lowering the activation energy required for the reaction to occur. In the case of urease, it facilitates the conversion of urea into ammonia and carbon dioxide. Understanding how enzymes function is crucial for predicting how changes in substrate concentration, like adding excess urea, will affect the reaction rate.
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Substrate Concentration

Substrate concentration refers to the amount of substrate available for an enzyme to act upon. According to the Michaelis-Menten kinetics, increasing substrate concentration can increase the reaction rate up to a certain point, known as Vmax, where all enzyme active sites are saturated. In this scenario, adding excess urea would initially increase the reaction rate until the enzyme becomes saturated.
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Steady State Kinetics

Steady state kinetics describes a condition where the concentration of the enzyme-substrate complex remains constant over time, indicating that the rate of formation of products equals the rate of breakdown of the complex. This concept is important for understanding how changes in substrate concentration, like adding excess urea, will influence the reaction rate without altering the overall enzyme concentration.
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Related Practice
Textbook Question

Indicate whether each of the following describes a competitive or a noncompetitive inhibitor.

e. Adding more substrate to the reaction restores the enzyme activity.

Textbook Question

Indicate whether each of the following describes a competitive or a noncompetitive inhibitor.

a. The structure of the inhibitor is similar to that of the substrate.

Textbook Question

How would the following changes affect enzyme activity for an enzyme whose optimal conditions are normal body temperature and physiological pH?

a. raising the temperature from 37 °C to 60 °C

Textbook Question

What level of protein structure is involved in the formation of an enzyme’s active site?

Textbook Question

Indicate whether each of the following describes a competitive or a noncompetitive inhibitor.

c. The inhibitor competes with the substrate for the active site.

Textbook Question

What kind of interaction attracts the cofactor Mg2+ and ATP to each other? (Hint: Look at the structure of the phosphate group.)