BIOL 2300 Exam # 2 Dynamics of Prokaryotic Growth (4.4-4.8)In laboratory, bacteria and archaea are typically grown either on agar plates or in tubes or flasks of broth-these are known as closed systems or batch cultures, because nutrients are not renewed, waste are also not removedTo maintain cells in a constant state of growth, nutrients must be added an d removed continuously, this is known as an open system or continuous cultureTHE GROWTH CURVE-A growth curve is characterized by five stages Lag phase- cells begin synthesizing enzymes required for growthLog phase (Exponential Phase)- cells divide at a constant rate -Bacteria are most sensitive to antimicrobial medications at this stage -Small molecules made by cells as they multiply are called primary metabolites-In later stages on exponential growth, nutrients gradually become depleted and waste productsaccumulate. If cells are able to form endospores, they initiate the process of sporulation -Compounds that begin accumulating at this stages are made for purposes other than growth are called secondary metabolites Stationary Phase- this is entered when nutrient levels are too low to sustain growth Death Phase- Period when the total number of viable cells in the population decreases as cells die off at a constant rate -Death is exponential, but the rate is much slowerPhases of Prolonged Decline- most of the surviving cells die-Microbial cells can be kept in a state of continuous growth by using a chemostat, this device continually drips fresh nutrients into the broth cultureEnvironmental Factors That Influence Microbial Growth-extremophiles are organisms that can grow in some of the harshest environments, and they arein the domain Archaea-the optimum growth temperature is the temperature at which the organism multiplies most rapidlyKNOW THIS CHART!!!!-Photoautotrophs- use energy from the sunlight to make ATP-Photoheterotrophs- use the energy from sunlight and derive their carbon from organic compounds -Chemolithoautotrophs- often referred to as chemoautotrophs use inorganic compounds for energy and derive their carbon from COsubscript 2-Chemoorganoheterotrophs- also referred to as chemoheterotrophs or chemoorganatrophs, useorganic compounds for energy and carbonControl of Microbial Growth-Sterilization- the removal or destruction of all microorganisms and viruses on or in a product-Sterile- item is one that is free of microbes, including endospores and virusesDoes not include prions-Disinfection- is the elimination of most or all pathogens on or in a material-Disinfectants- antimicrobial chemicals used for disinfecting inanimate objectsGermicides target microorganisms and virusesAntiseptics antimicrobial chemicals non-toxic enough to be used on skin or other body tissue -Pasteurization- a brief heat treatment that reduces the number of spoilage organisms and destroys pathogens -Decontamination- A process used to reduce the number of pathogens to a level considered safe to handle -Sanitization- implies a process that substantially reduces the microbial population to meet accepted health standards-Preservation- the process of delaying spoilage of foods or other perishable productsBacteriostatic- meaning they inhibit the growth of bacteria but do not kill them-Understand nosocomial infections and how they are acquired-Know the physical and chemical ways to remove microbes (5.4-5.5)Bacterial GeneticsNatural selection is when the environment selects the most fit traits in an organism to surviveKnow what phenotype and genotype are Understand spontaneous mutations the definition and types included….point mutation, nonsense mutation etc-Go over and understand the basic concepts of viruses, viroid’s and prions, what they are, what organisms cause them and if they can be treated (Chapter