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Multiple Choice
In microbial control, how do alcohols (e.g., ethanol or isopropanol) chemically “fix” bacteria?
A
By alkylating DNA bases and creating covalent cross-links that block replication
B
By oxidizing sulfhydryl groups using hypochlorous acid to form disulfide bonds
C
By denaturing proteins and disrupting lipid membranes, leading to dehydration and coagulation of cellular components
D
By inhibiting folic acid synthesis through competitive inhibition of dihydropteroate synthase
Verified step by step guidance
1
Understand that 'chemical fixation' in microbial control refers to the process by which a chemical agent causes irreversible damage to microbial cells, effectively killing or inactivating them.
Recognize that alcohols like ethanol and isopropanol primarily act by interacting with proteins and lipids in the bacterial cell.
Recall that alcohols denature proteins by disrupting their secondary and tertiary structures, which impairs enzyme function and structural integrity.
Note that alcohols also disrupt the lipid bilayer of the bacterial cell membrane, increasing permeability and causing leakage of cellular contents.
Combine these effects to see that alcohols cause dehydration and coagulation of cellular components, leading to cell death, which is the basis for their chemical 'fixation' action.