BIOS 2150 Microbiology Class Notes Review

• What is the role of oxygen in bacterial metabolism? • What about carbon? • Explain how a low pH affects bacterial metabolism. Shuts down metabolism because it ruins the enzymes that the bacteria need to survive. • ...

• What is the role of oxygen in bacterial metabolism? • What about carbon? • Explain how a low pH affects bacterial metabolism. Shuts down metabolism because it ruins the enzymes that the bacteria need to survive. • Bacteria have varying oxygen requirements. Which category describes those that would grow deep in the soil? o Obligate aerobic- requires oxygen for energy production as an electron acceptor o Facultative anaerobic- can thrive in oxygen but can also use another electron acceptor if oxygen is not available. Can go with or without oxygen o Obligate anaerobic- oxygen is harmful to them because they don’t have catalase and SOD Symbiosis (Section 4.1 Page 152) • Close association between two unlike organisms that is beneficial to one or both of them. 1. Parasitism • The interaction is between a host and a parasite • The parasite lives on the host, at the expense of the host. The host is giving something to the parasite that it needs to survive. The host is harmed by the interaction. The parasite may end up killing off the host but its not trying to… just happens to weaken it enough that it can survive • Examples: Cedar-apple rust; powdery mildew; heartworm in a dissected dog heart 2. Mutualism • An interaction where both organisms benefit each other • These two organisms aren’t going to do as well if they live apart • Examples: protozoa that live in the digestive tract of termites; lichen: an algae and fungus living together; cattle and microbes (protists and bacteria) in their stomach; bacteria that humans carry in us (normal flora) • (Chapter 26 page 1051 Key Terms: o Competitive exclusion: when you have two organisms competing for the same resources, one of them is going to win and one will lose o Bacteriosins: chemicals that bacteria manufacture to kill off other bacteria. Once they lay down bacteriosins other bacteria have a much harder time establishing themselves. 3. Commensalism • An interaction where one organism benefits and the host is not affected • Some normal skin flora • Fungus or lichens on tree bark • Dust mites in your house