Ch. 5 - Microbial Metabolism

Tortora - Microbiology: An Introduction 14th Edition

Tortora14th EditionMicrobiology: An IntroductionISBN: 9780138200398Not the one you use?Change textbook

Tortora 14th Edition

Ch. 5 - Microbial Metabolism

Problem 3

Chapter 5, Problem 3

An enzyme and substrate are combined. The rate of reaction begins as shown in the following graph. To complete the graph, show the effect of increasing substrate concentration on a constant enzyme concentration. Show the effect of increasing temperature.

Verified step by step guidance

Understand that the graph initially shows the reaction rate when enzyme and substrate are combined at certain concentrations and conditions.

To show the effect of increasing substrate concentration at constant enzyme concentration, recall that the reaction rate will increase as substrate concentration increases, but only up to a point where the enzyme becomes saturated. This results in a curve that rises steeply at first and then levels off, approaching a maximum velocity (Vmax).

Represent this by drawing a hyperbolic curve that starts at the origin, rises sharply, and then plateaus, indicating that adding more substrate beyond saturation does not increase the rate further.

To show the effect of increasing temperature, remember that reaction rate generally increases with temperature due to higher kinetic energy, up to an optimum temperature. Beyond this optimum, the enzyme denatures and the rate sharply decreases.

Illustrate this by drawing a curve that rises with temperature to a peak (optimum temperature) and then falls off rapidly, showing enzyme denaturation and loss of activity at higher temperatures.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.

Video duration:

Was this helpful?

Key Concepts

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

Enzyme-Substrate Interaction and Reaction Rate

Enzymes bind to substrates to form an enzyme-substrate complex, facilitating the conversion to product. The reaction rate initially increases with substrate concentration as more substrate molecules are available, but eventually plateaus when all enzyme active sites are saturated, showing a maximum velocity (Vmax).

Effect of Substrate Concentration on Enzyme Activity

Increasing substrate concentration at a constant enzyme level raises the reaction rate until the enzyme becomes saturated. Beyond this point, adding more substrate does not increase the rate, resulting in a hyperbolic curve typical of Michaelis-Menten kinetics.

Effect of Temperature on Enzyme Activity

Temperature influences enzyme activity by affecting molecular motion and enzyme stability. As temperature rises, reaction rate increases up to an optimum point due to faster collisions, but beyond this, enzymes denature and activity sharply decreases.

Recommended video:

Guided course

04:18

Enzyme Activation Energy

Related Practice

Textbook Question

Which of the following compounds has the greatest amount of energy for a cell?

a. CO₂

b. ATP

c. glucose

d. O₂

e. lactic acid

views

Textbook Question

Which of the following reactions produces the most molecules of ATP during aerobic metabolism?

a. Glucose → Glucose 6-phosphate

b. Phosphoenolpyruvic acid → Pyruvic acid

c. Glucose → Pyruvic acid

d. Acetyl CoA → CO₂ + H₂O

e. Succinic acid → Fumaric acid

Textbook Question

Define oxidation-reduction, and differentiate the following terms:

a. Aerobic and anaerobic respiration

b. Respiration and fermentation

c. Cyclic and noncyclic photophosphorylation

views

Textbook Question

Using the following diagrams, show each of the following:

a. where the substrate will bind

b. where the competitive inhibitor will bind

c. where the noncompetitive inhibitor will bind

d. which of the four elements could be the inhibitor in feedback inhibition

e. What effect will the reactions in (a), (b), and (c) have?

Textbook Question

Which of the following processes does not generate ATP?

a. Photophosphorylation

b. The Calvin-Benson cycle

c. Oxidative phosphorylation

d. Substrate-level phosphorylation

e. All of the above generate ATP

views

Textbook Question

There are three mechanisms for the phosphorylation of ADP to produce ATP. Write the name of the mechanism that describes each of the reactions in the following table.

views