Skip to main content
Ch. 5 - Microbial Metabolism
Tortora - Microbiology: An Introduction 14th Edition
Tortora14th EditionMicrobiology: An IntroductionISBN: 9780138200398Not the one you use?Change textbook
All textbooksTortora 14th EditionCh. 5 - Microbial MetabolismProblem 2
Chapter 5, Problem 2

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?
Diagram showing enzyme, substrate, competitive inhibitor, and noncompetitive inhibitor as distinct molecular shapes.

Verified step by step guidance
1
Step 1: Identify the substrate binding site on the enzyme diagram. This is typically the active site where the substrate fits specifically, often shown as a complementary shape or pocket on the enzyme surface.
Step 2: Locate the competitive inhibitor binding site. Competitive inhibitors bind directly to the active site, competing with the substrate for the same spot, so mark the active site again but indicate the inhibitor binding there instead of the substrate.
Step 3: Identify the noncompetitive inhibitor binding site. Noncompetitive inhibitors bind to a different site on the enzyme, called the allosteric site, which is separate from the active site. Mark this distinct site on the enzyme where the noncompetitive inhibitor attaches.
Step 4: Determine which of the four elements in the diagram could act as the inhibitor in feedback inhibition. Feedback inhibition usually involves the end product of a metabolic pathway binding to an allosteric site on an earlier enzyme to regulate the pathway. Identify the element that fits this description and mark it as the feedback inhibitor.
Step 5: Explain the effects of the reactions in (a), (b), and (c): (a) substrate binding leads to enzyme catalysis and product formation; (b) competitive inhibitor binding blocks substrate access to the active site, reducing enzyme activity; (c) noncompetitive inhibitor binding changes enzyme shape, decreasing its activity regardless of substrate presence.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
3m
Was this helpful?

Key Concepts

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

Enzyme-Substrate Binding

Enzymes have specific active sites where substrates bind to form an enzyme-substrate complex, facilitating the chemical reaction. This binding is highly specific, often described by the 'lock and key' or 'induced fit' models, ensuring that only the correct substrate fits into the active site.
Recommended video:
Guided course
03:49
Enzyme-Substrate Complex

Types of Enzyme Inhibition

Competitive inhibitors bind to the enzyme's active site, directly blocking substrate binding, while noncompetitive inhibitors bind to an allosteric site, changing the enzyme's shape and reducing its activity. Both types decrease enzyme efficiency but through different mechanisms.
Recommended video:
Guided course
05:03
Enzyme Inhibition

Feedback Inhibition in Metabolic Pathways

Feedback inhibition occurs when the end product of a metabolic pathway acts as an inhibitor, usually noncompetitive, to an earlier enzyme, regulating the pathway's activity. This prevents overproduction of the product and maintains cellular homeostasis.
Recommended video:
Guided course
02:41
Negative Feedback
Related Practice
Textbook Question

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.

1507
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

1410
views
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

1279
views
Textbook Question

Use the following diagrams (a), (b), and (c) for the question.

<IMAGE>


Name pathways diagrammed in parts (a), (b), and (c) of the figure.

a. Show where glycerol is catabolized and where fatty acids are catabolized.

b. Show where glutamic acid (an amino acid) is catabolized:

<IMAGE>

c. Show how these pathways are related.

d. Where is ATP required in pathways (a) and (b)?

e. Where is CO₂ released in pathways (b) and (c)?

f. Show where a long-chain hydrocarbon such as petroleum is catabolized.

g. Where is NADH (or FADH₂ or NADPH) used and produced in these pathways?

h. Identify four places where anabolic and catabolic pathways are integrated.

1284
views
Textbook Question

Which substance in the following reaction is being reduced?

a. Acetaldehyde

b. NADH

c. Ethanol

d. NAD+

1339
views