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# Chapter 11 Notes ## Denaturation * In general, denaturation occurs when the bonds that maintain the secondary and tertiary structure of the protein are broken. * Breaking these bonds will cause the protein to unfold or create random, irregular loops and coils. ## Microorganisms and Habitats *...

# Chapter 11 Notes ## Denaturation * In general, denaturation occurs when the bonds that maintain the secondary and tertiary structure of the protein are broken. * Breaking these bonds will cause the protein to unfold or create random, irregular loops and coils. ## Microorganisms and Habitats * Microorganisms have adapted to a tremendous diversity of habitats on earth, some having severe conditions of temperature, moisture, pressure, and light. * Most common antimicrobial physical agents is heat. * Others include radiation and filtration. ## Heat * Moist heat and dry heat differ in their modes of action as well as their efficiency. * Higher temperature allows shorter exposure time, lower temperature requires longer exposure time. * A combination of these 2 variables constitutes the thermal death time: shortest length of time required to kill all test microbes at a specified temperature. * Thermal death point: defined as the lowest temperature required to kill all microbes in a sample in 10 minutes. * Pasteurization is a technique of applying heat to consumable liquids to kill potential agents of infection and spoilage, while at the same time retaining the liquid's flavor and food value. * Cold merely retards the activities of most microbes. ## Irridation * Irridation: the application of radiant energy for diagnosis, therapy, disinfection, or sterilization. * If the radiation ejects orbital electrons from an atom, it causes ions to form: this type of radiation is termed ionizing radiation. ## Nonionizing Radiation * Nonionizing radiation, best exemplified by UV, excites atoms by raising them to a higher energy state, but it doesn't ionize them. * Drugs, vaccines, medical instruments, and other delicate materials can be irradiated without harming them. * Ultraviolet radiation is usually aimed more at disinfection.