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50 Cards in this Set
- Front
- Back
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what is microbial growth?
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Increase in the number of cells
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how do most microorganisms reproduce?
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binary fission
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Generation time-doubling time
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time required to double the number of bacteria cells
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Septum Formation
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is triggered by attainment of threshold length and mass, and the completion of DNA replication
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Replisomes
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Where DNA replication occurs
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FtsZ protein
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defines the division plane in prokaryote
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MreB protein
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help define cell shape
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Glycan units
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are inserted into preexisting cell walls and assist in the synthesis of a new bacterial cell wall
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Bactoprenol
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is a hydrophobic alcohol that facilitates transport of new glycan units
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Transpeptidation:
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the transfer of one or more amino acids between peptides
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Exponential Growth
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the rate at which bacterial cells grow
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What is the stationary phase in cell growth
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If nutrients are depleted or toxic products build up, cell growth ceases and the cell enters the stationary phase
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What happens if incubation continues
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cells may begin to die
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Direct Measurements of Microbial Growth:
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Total and Viable Counts
Total cell count |
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bacterial cell growth is measured
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by the total amount of cell change over a period of time
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Viable Count
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measures only the living organisms
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Turbidity
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Turbidity measurements are an
indirect but very rapid and useful method of measuring microbial growth. |
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Spectrophotometer
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used to measure cell density via turbidity
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Continuous culture devices:
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Chemostat
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Chemostats are:
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are a
means of maintaining cell populations in exponential growth for long periods |
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population size is governed by:
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the concentration of the growth-limiting nutrient
entering the vessel |
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What is a major environmental factor that controls microbial growth?
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Temperature
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What do the cardinal temperatures describe?
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they describe the minimum, optimum, and maximum temperatures at which an organism can/will grow
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What does a cryoprotectant do?
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it is a substance that keeps biological tissue from freezing damage
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What are 2 examples of a cryoprotectant?
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Glycerol and dimethyl sulfoxide (10%)
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What are thermophiles?
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bacteria that can withstand very high temp environments
they have lipid with very high saturated fatty acid which helps maintain membrane stability |
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What are hyperthermophiles?
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hyperthermophiles are archea and they do not contain fatty acids instead they have C40 hydrocarbons which are repeating 5 carbon rings
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what pH level do most microorganisms grow in?
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they grow in a pH level between 6 and 8.
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What are organisms called that can live with or without oxygen?
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facultative
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What is a superoxide?
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it is a common toxic oxygen species
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what is antimicrobial?
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a disinfectant, such as heat, radiation, or a chemical that destroys microorganisms that may carry diseases
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What is an autoclave?
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A device used to steralize equipment by heating it beyond its boiling point to 121 C with high pressure steam, this usually takes 15 to 20 min
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What do autoclaves destroy?
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noncovalent bonds in proteins and DNA
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What are noncovalent bonds good for?
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they are good for forming secondary and tertiary bonds
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What is steralization?
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the killing of all organisms including viruses, heat is usually used
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What are the most heat-resistant organisms?
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Endospores
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What is pasteurization?
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pasteurization does not steralize liquids, but reduces the microbial load, killing most pathogens and inhibiting the growth of spoilage microorganisms
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What is UV radiation used for?
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UV radiation is used to decontaminate surfaces and materials that do not absorb light, such as air and water
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What does electromagnectic radiation do?
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It affectively inhibits mircrobial growth
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What is ionizing radiation used for?
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It is used to decontaminate solids that absorb light, it is highly used in the medical and food industries
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What are the physical methods of microbial control
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filtration
Temperature *freezing, refrigerate, lyophilization High pressure denatures proteins Desiccation prevents metabolism Osmotic pressure causes plasmolysis |
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What are chemicals called that kill orgranisms
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Cidal agents
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What are chemicals called that inhibit growth of organisms
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Static agents
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What is inanimate?
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nonliving objects
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What is animate?
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Living things
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When was the first successful clinical trial of penicillin
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1940: howard florey and ernest chain
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what are the most important clinical antibiotics
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beta lactam compounds
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Quinolones
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they keep bacterial DNA from unwinding and duplicating
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How do many antibiotics function?
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They inhibit transcription or translation in many microorganisms
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What is an Interferon
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Influenza Antiviral Agent
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