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Ch. 7 - The Control of Microbial Growth
Chapter 7, Problem 7.3a

Which of these disinfectants does not act by disrupting the plasma membrane?
a. phenolics
b. phenol
c. quats
d. halogens
e. biguanides

Verified step by step guidance
1
Identify the mechanism of action for each disinfectant option provided.
Understand that phenolics and phenol disrupt the plasma membrane by denaturing proteins and disrupting cell membranes.
Recognize that quats (quaternary ammonium compounds) also disrupt the plasma membrane by affecting the lipid bilayer.
Note that biguanides, like chlorhexidine, disrupt the plasma membrane by affecting the integrity of the cell membrane.
Realize that halogens, such as iodine and chlorine, primarily act by oxidizing cellular components and proteins, not by disrupting the plasma membrane.

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Key Concepts

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

Disinfectants and Their Mechanisms

Disinfectants are chemical agents used to eliminate or reduce harmful microorganisms on surfaces. They can act through various mechanisms, including disrupting the plasma membrane, denaturing proteins, or interfering with nucleic acids. Understanding how different disinfectants function is crucial for selecting the appropriate agent for specific applications.
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Plasma Membrane Disruption

The plasma membrane is a critical barrier that surrounds and protects the cell, composed mainly of phospholipids and proteins. Disinfectants that disrupt the plasma membrane compromise its integrity, leading to cell lysis and death. Identifying which disinfectants act through this mechanism helps in understanding their effectiveness against various pathogens.
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Types of Disinfectants

Different classes of disinfectants include phenolics, quaternary ammonium compounds (quats), halogens, and biguanides, each with unique properties and mechanisms of action. For instance, phenolics and halogens typically disrupt membranes, while quats may act through different pathways. Recognizing these distinctions is essential for determining which disinfectant does not disrupt the plasma membrane.
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