Chemicals that kill or inhibit microorganisms on living tissue or surfaces.
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Antiseptics are chemicals applied to living tissue to kill or inhibit microorganisms, while disinfectants are used on inanimate surfaces and objects. Common antiseptics include iodine, hydrogen peroxide and alcohols, and common disinfectants include chlorine bleach and phenol. Most act by denaturing proteins, oxidising essential molecules or disrupting cell membranes, and they are not highly selective between microbe and host cell. Their effectiveness depends on concentration, contact time, temperature and the presence of organic matter such as blood. Overuse or misuse can select for tolerance and cause skin irritation.
Key ideas: Antiseptics are applied to living tissue (dilute iodine tincture, hydrogen peroxide, 70 percent ethanol, boric acid); disinfectants are for inanimate surfaces (chlorine bleach, phenol, formaldehyde). The same chemical can be either depending on concentration, e.g. phenol 0.2 percent antiseptic and 1 percent disinfectant.
Common mistakes and connections: Students think stronger is always better; 70 percent ethanol beats 100 percent because water helps it penetrate cell walls before coagulating proteins. Disinfectants on skin cause burns. Neither is the same as antibiotic, which acts inside the body. Links to denaturation and water chlorination.
Typical working concentrations of common antiseptics. The 70 percent alcohols work better than pure alcohol because water helps them penetrate and denature microbial proteins. The interactive lesson shows this as a live animation or chart.
70 percent ethanol is more effective than pure ethanol because some water is needed to penetrate and denature microbial proteins.
Chemicals that kill or inhibit microorganisms on living tissue or surfaces.
Antiseptics and Disinfectants is a beginner topic in Biochemistry, Environment & Industry. It needs no earlier chemistry lessons and is a good starting point.
Study these earlier topics in Biochemistry, Environment & Industry first: Drug Action, Antibiotics, Analgesics.
The next topics in Biochemistry, Environment & Industry are Food Preservatives and Artificial Sweeteners.
Yes. The interactive lesson includes a self-check question on Antiseptics and Disinfectants, and the Biochemistry, Environment & Industry quiz draws on every topic in this area.
Antiseptics and Disinfectants is topic 45 of 127 in Biochemistry, Environment & Industry.
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