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# Chapter 7 Notes ## Carbon Source * **Heterotroph:** Microbe that must obtain its carbon in an organic form. * **Autotroph:** Microbe that uses inorganic CO₂ as its carbon source. ## Energy (ATP) Source * **Phototroph:** Microbe that photosynthesizes. * **Chemotroph:** Microbe that gets its ene...

# Chapter 7 Notes ## Carbon Source * **Heterotroph:** Microbe that must obtain its carbon in an organic form. * **Autotroph:** Microbe that uses inorganic CO₂ as its carbon source. ## Energy (ATP) Source * **Phototroph:** Microbe that photosynthesizes. * **Chemotroph:** Microbe that gets its energy from chemical compounds. ## Passive Transport * Does not require energy ## Solutions * **Hypotonic solution:** Net diffusion of water into the cell; this swells the protoplast and pushes it tightly against the wall. The wall usually prevents the cell from bursting. * **Hypertonic solution:** Water diffuses out of the cell and shrinks the cell membrane away from the cell wall. ## Temperatures for Microbial Growth * **Minimum temperature:** The lowest temperature that permits a microbe's continued growth and metabolism; below this temperature, its activities stop. * **Maximum temperature:** The highest temperature at which growth and metabolism can proceed before proteins are denatured. * **Optimum temperature:** The best temperature that promotes the fastest rate of growth and metabolism. ## Types of Microbes Based on Temperature Preference * **Psychrophiles:** Cold-loving microbes; optimum temperature below 15°C; cannot grow above 20°C. Important in food spoilage. * **Psychrotrophs:** Optimum temperature between 15°C and 30°C; able to grow at refrigerator temperatures and cause food-borne illness.