Exam 2 potiental essay questions Explain how the Cholera toxin kills cells The toxic portion hops from molecule to molecule, disabling each one List the differences between DNA and RNA. RNA is transcribed from a gene. DNA hereditary material DNA is double stranded. RNA is single-stranded Describe the four levels of protein folding. Primary structure •Secondary structure •Tertiary structure •Quaternary structure Describe the chemical differences between Gram-negative and Gram-positive cells. Gram-negative are surrounded by a thin peptidoglycan cell wall, which is surrounded by an outer membrane Gram-positive doesn't have an outer membrane & has a thick peptidoglycan Describe the process of Binary Fission One parent cell divides and forms two offspring cells Describe the process of chemotaxis in bacteria. Bacteria rapidly response to changes in the chemical composition of their environment Explain how carbon and nitrogen are cycled in bacteria. They break down dead animal & plant matter, they act as decomposers Bacteria converts ammonia to nitrates Describe the growth cycle of a typical bacterial colony. Lag Phase : Bacteria are preparing their cell machinery for growth Log Phase : Growth approximates an exponential curve ( straight line, on a logarithmic scale) Stationery Phase: Cells stop growing & shut down their growth machinery while turning on stress responses to help retain viability Death Phase: Cells begin to die at an exponential rate. What is a biofilm and how does it form? Cellular flagella attach to monolayer Microcolonies form Surface attached communities Biofilm forms when bacteria attach to surfaces in moist environments Plaque on teeth is a multispecies biofilm Cells produce EPSs