Alcohols usually affect microbes by ______.

• A. inhibiting DNA replication
• B. interfering with cell wall synthesis
• C. denaturing proteins and disrupting cell membranes
• D. blocking ribosome function

Answer: (C)

Verified step by step guidance

1. Understand that alcohols are commonly used as disinfectants and antiseptics in microbiology due to their ability to kill or inhibit microbial growth.
2. Recall that the primary mechanism by which alcohols affect microbes is by targeting proteins and membranes rather than directly interfering with DNA replication, cell wall synthesis, or ribosome function.
3. Recognize that alcohols cause denaturation of proteins, which means they disrupt the three-dimensional structure of proteins, rendering them nonfunctional.
4. Note that alcohols also disrupt the lipid bilayer of microbial cell membranes, increasing membrane permeability and leading to leakage of cellular contents.
5. Conclude that the combined effect of protein denaturation and membrane disruption leads to microbial cell death, which is why the correct answer is 'denaturing proteins and disrupting cell membranes.'