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30 Cards in this Set
- Front
- Back
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What are the three ways to measure the number of cells in a sample?
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total count
viable count light scattering |
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Describe total count.
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Total count is a direct means of measuring the number of cells in a sample by which you simply take the sample, place it on a slide, and count the physical number of cells.
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Describe viable count.
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Viable count is a direct means of measuring the number of cell sin a sample by which you take a sample, take several dilutions of that sample, plate the dilutions and count the colonies.
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How do you calculate viable count?
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Viable Count [Cfu/ml] = (# colonies)(dilution factor)(plating factor)
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How many colonies should be present to ensure a reasonable error with viable count?
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30 to 100 is ideal
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If you diluted the culture by a factor of 10^6 and plated 0.1ml, and got 37 colonies on the plate, what is the viable count?
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3.7E8
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Describe the process of light scattering.
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Light scattering is an indirect method of counting the number of cells in a sample by which a light is passed through a tube of cells and the light is measured by a spectrophotometer and you can make a correlate calculation of number of cells based on the amount of light that passes through the sample. It is the most common method of counting cells.
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What are the three phases of bacterial growth?
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Lag, exponential, stationary, (death)
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aerobe
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Can use oxygen to grow, but does not inherently have to. If oxygen is used, then it uses respiration.
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obligate aerobe definition and examples
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MUST have oxygen, specifically at atmospheric concentrations, to grow. mycobacterium and pseudomonas
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microaerophiles definition and examples
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MUST have oxygen, but it must not be at atmospheric concentration. must be lower. campylobacter, helicobacter.
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facultative anaerobes definition and examples
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can go do either one. if there is oxygen present, it will be used. if there is no oxygen, they resort to fermentation. escherichia.
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anaerobe
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CAN NOT use oxygen to grow.
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obligate anaerobes definition and examples
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oxygen will kill these bad boys. so not only can they not use oxygen, but they can't be around oxygen at all. bacteroides, clostridium.
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why does lactose intolerance occur and what form of metabolism is it associated with?
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lactose intolerance is a result of the lack of the lactase enxzyme in the small intestine. lactose cannot then be metabolized, so it travels to the large intestine. in there, the residual bacteria get to work fermenting that lactose. the unfortunate byproduct is gas, acid -> diahrea
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what causes gas gangrene and describe it?
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myonecrosis is caused by C. perfrengens infection in wounds and it uses fermentation and produces gas that spreads out tissue layers to that it can spread more easily.
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psychrophile
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bacteria that grows in temp up to 20C
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mesophile
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grows from 25C to 40C, which is at body temp
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thermophile
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45C to 80C
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psychrotolerant
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they don't like cold, but hey... they can deal. mesophile by choice, psychrophile by force.
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grows in refrigerated blood supplies and is a psychrophile
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Yersinia enterocolitica
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grows in refrigerated food, specifically cabage and is a psychrophile. immunocompromised pts have a 25% mortality rate
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Listeria monocytogenes
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biofilm
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sessile growth is on surfaces of tissues. a few cells attach to the surface and cells send chemical signals out to indicate that there are enough cells to form a colony. these chemical signals cause a lot of polysaccharide to be formed which help new bacteria attach and old bacteria stay on. that polysaccharide is the biofilm.
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give two examples of biofilm
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dental plaque caused by Streptococcus mutans that causes a microenvironment for anearobic growth. cystic fibrosis is complicated by indirect Pseudomonas aeruginosa infection and biofilm.
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what important process must be functional for bacterial metabolism to continue?
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oxidation of NADH because of glycolysis in both fermentation and respiration
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What is the flow of bacterial respiration?
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ETC - Dehydrogenase -> Quinone -> Terminal Reductase -> ATPase
(1) removes hydrogens from NADH and moves them from cytoplasm to periplasm. takes 2e- from conversion and passes to (2), (2) passes to (3). (3) makes water with additional 2e- and O2 radical. So (3) uses O2 to oxidize NADH, which provides the gradient for (4) to make ATP. |
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What is the significance of Vitamin K in bacterial aerobic respiration?
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Vit K is a type of Quinone: menaquinone. Humans get their K from intestinal flora and food. K defficiency reduces blood clotting, so if you kill interstinal flora w/ antibiotics, then you need to make sure to supplement Vit K in diet.
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What types of bacterial species use fermentation for metabolism?
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anaerobes. they do not have an ETC, but they still must oxidize NADH back to NAD+, so they use fermentation
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What are the main biproducts of bacterial fermentation?
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acids and gases - succinate, lactate, CO2, H2, formate, ethanol, acetate
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What is an example of an anaerobic bacteria that uses fermentation?
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E. coli
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