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Stack #168546
| Question | Answer |
|---|---|
| Hyperthemophiles (extreme thermophiles) | These are found in volcanoes. One species can grow at 121°C (boiling water is 100°C). These are members of Domain Archaea. |
| Mesophiles | Grow well at room temperature and at body temperature. Most human pathogens are mesophiles. Some can divide every 20 minutes. |
| Psychrotrophs | Grow at slightly warmer temperatures than cold-loving ones. These microbes can grow better than most other microbes at near freezing temperatures and can grow well at room temperature. These microbes are responsible for spoiling food in the refrigerator. |
| pH | refers to the concentration of H+ in a solution. |
| High pH (pH | 7) refers to: (2 names)>a basic solution (alkaline). |
| Low pH (pH < 7) refers to | an acidic solution. |
| Buffer | solution that resists changes in pH |
| Acidophiles | microorganisms that grow at low pH; very few bacteria; yeasts and fungi can grow and spoil at pH 5-6 |
| Osmotic pressure | pressure caused by differences in solution concentrations across a selectively permeable membrane |
| Isotonic | concentration same on both sides |
| Hypotonic | concentration is less on this side than other side |
| Hypertonic | concentration is higher on this side than other side |
| plasmolysis | loss of water by osmosis |
| halophiles | grow in salty solutions |
| Obligate halophiles | require salt for growth. |
| facultative halophiles | don't require salty solutions for growth but can tolerate them. |
| heterotrophs | get carbon from organic materials (eg, humans) |
| autotrophs | get carbon from "fixing" CO2 gas; there are 2 types of autotrophs |
| photoautotrophs | get energy from light, and carbon from CO2 gas |
| chemoautotrophs | Get energy from inorganic materials such as hydrogen sulfide, sulfur, ammonia, nitrate, hydrogen gas, ferrous iron, etc.). Get carbon from CO2 gas. |
| Chemoheterotrophs | Get energy and carbon from organic materials. We (humans) are __________s. |
| Important chemicals needed | carbon, nitrogen, sulfur, phosphorus |
| nitrogen is used for... | is used to build proteins, nucleic acids. |
| nitrogen is gotten by... | Most organisms that we are familiar with gain ____ from other organisms (digestion, decomposition); some get it from ammonium or nitrate. Others get it from atmosphere, photosynthesis by cyanobacteria.. |
| NITROGEN is necessary for... | all MICROORGANISMS require a source of (not s, p, c, or o)... |
| Phosphorus is necessary for... | all MICROORGANISMS require a source of (not s, n, c, or o)... |
| Sulfur is necessary for... | all MICROORGANISMS require a source of (not p, n, c, or o)... |
| Oxygen is necessary for... | only SOME microoganisms need this, which is thought to contribute to aging... |
| sulfur is used for... | proteins and vitamins; also chemoautotrophs use this for energy etc. |
| Calcium, potassium, and magnesium are used for | ...are used for a variety of purposes. They can be used for signaling or can be used as cofactors for enzymes. Remember that enzymes are biological catalysts and are used to assemble organic compounds (nucleic acids, proteins) and break down materials for |
| cofactors | A substance, such as a metallic ion or another enzyme, that must be associated with an enzyme for the enzyme to function. |
| Trace elements (copper, iron, zinc, molybedum) are useful for...are gotten by... | are useful as enzyme cofactors. These are often found in tap water, so they don’t have to be added to bacterial growth media. |
| Organic growth factors (vitamins**, amino acids, purines, pyrimidines). Used for ... | These are the building blocks used to assemble proteins and nucleic acids. Some microorganisms can assemble these from scratch, but many need to get these from another source in order to grow. (the first item in the parenthesis list is a thing that are of |
| we require ... for respiration, energy generation in mitochondria | we require oxygen for... |
| reactive ----- species are ---- | oxygen ... toxic |
| list of the reactive oxygen species | Singlet oxygen (1O2-) Superoxide (O2-) Peroxide (O22-) Hydroxyl radical (OH?) Ozone (O3) |
| oxidizing agents damage what? and the damage does what? | damage nucleic acids, fatty acids, etc. Damage to DNA produces mutations, phospholipids damages plasma membrane. |
| oxidizing agents are used usefully by | phagocytes |
| phagocytes (are) | (name for) macrophages of the immune system |
| SOD | Superoxide dismutase |
| Superoxide dismutase | neutralizes superoxide and produces hydrogen peroxide... O2- + O2- + 2H+ -> H2O2 + O2 |
| Catalase | Converts hydrogen peroxide to water and oxygen gas. 2H2O2 -> 2H2O + O2 |
| obligate aerobes | require oxygen for growth |
| facultative anaerobes (define, give example) | can use oxygen when present, but grow ok (but less) without oxygen. Examples: yeast, E.coli; |
| All oxygen-using microbes need these enzymes | catalase and superoxide dismutase |
| obligate anaerobes (define, give example) | cannot survive in oxygen, must have non-oxygen environ. Example is clostridium. |
| Aerotolerant anaerobes (define, give example) | Cannot use oxygen but are tolerant. An example includes Lactobacillus, a microorganism used to make yogurt and cheese. Have superoxide dismutase, no catalase. |
| Microaerophiles | These do require oxygen, but at a much lower concentration than is present in the atmosphere. These microorganisms probably produce less superoxide dismutase and catalase. |
| culture media (define, explain) | artificial growth environment for microorganisms is called ---, and can be liquid or solid; it must be sterilized. |
| Liquid culture media (explain) | define: ---- is sometimes called broth, and you can mix agar with it to make it non---- |
| agar | polysaccharide used to make liquid culture media into a solid media. Most bacteria can't metabolize it, and it melts near 100C but remains liquid near 40C; it can be incubated near 100C, and there are many types. |
| chemically defined media | the exact composition of this media is known; Used to grow chemoautotrophs and photoautotrophs, or this medium can be used to test the effect of a specific component (vitamin) on the rate of growth. |
| complex media | The exact composition of the medium is not known. This is used in routine lab work for growing chemoheterotrophs. This type of media is made from extracts of plants, meat, and yeast to provide vitamins and organic growth factors. It also contains digested |
| Liquid complex media is called | *nutrient* broth, |
| solid complex media is called | *nutrient* agar. |
| Selective media (what is it; example) | This type of media is helpful for studying disease causing microorganisms because it suppresses the growth of unwanted microorganisms and allows for the desired microorganism. An example is bismuth sulfite agar, which prevents the growth of most Gram pos |
| Plaque method | Growth of bacteriophages on solid media. This is typically done by mixing bacteria, bacteriophages, and melted agar, then pouring on the surface of an agar plate. The bacteria grow to make a “lawn,” a layer of bacteria on the surface of the plate. As the |
| plaques | clear areas on a lawn of bacteria, caused by bacteriophages |
| PFU - determines the number of ---- or the concentration of viruses on a solid media | plaque forming units |
| in vivo | viruses maintained in animals are called |
| three ways viruses are maintained | in vivo, in embryonated eggs, in cell culture |
| CPE(cytopathic effect) | when animal cell's biological properties change thanks to virus infections (eg, a monolayer on a surface becomes rounded or piled up) |
| transformed | cells affected by the CPE are said to be... |
| primary cell lines | cells or tissue slices derived from tissue; die after a few generations |
| diploid cell lines | derived from human embryos, used to culture human viruses |
| continuous cell lines | transformed tissue cultures with cancerlike properties; maintained indefinitely; produce viral particles indefinitely |
| binary fission | bacteria reproduction by splitting via invagination. |
| methods of cell reproduction | binary fission, budding, produce chains of conidiospores, fragmenting |
| four stages of bacterial growth | lag phase, log phase, stationary phase, death phase |
| Lag phase | A period of time where little cell division occurs. It is a period of intense metabolic activity, where enzymes and molecules are synthesized. |
| Log phase | A period of time where cells divide rapidly. This is a time when the generation time is the smallest. This phase of growth is where many cellular products are synthesized, including the cell wall. Thus Gram positive cells are susceptible to penicillin du |
| Stationary phase | A period where the growth rate slows and the resources (nutrients) in the culture medium are exhausted. Here waste products accumulate, and changes of pH slow growth. During this phase the rate of cell growth and the rate of cell death are roughly equal. |
| Death Phase | A period where the rate of death exceeds the rate of growth. The population may die off completely or very few cells will remain. The cells in the solution may look sick. Involution occurs. |
| Involution | when dying, cell morphologies can change dramatically |
| A spectrophotometer | is used to measure turbidity; used to estimate number of bacteria in a cell, not measure accurately. Two types of measurement are transmission and absorbance. |
| is called sterilization. | To remove all traces of life, for example from a piece of surgical equipment or a solution; would refer to the removal of endospores, as well. |
| The sterilizing agent is called | the sterilant. |
| Commercial sterilization | a term used to describe the process of killing Clostridium endospores in canned foods. Destruction of all life by further heating would damage the quality of the food. |
| Disinfection, disinfectants, refers to | the removal of all harmful microorganisms. usually removes growing (vegetative) cells. It does not destroy endospores. Surfaces are ---- using chemicals called --- , UV radiation, boiling water, or steam. |
| antisepsis. | When you try to remove pathogens from the surface of living tissue, the process is called ---; |
| A chemical used to remove the pathogens is called an | antiseptic |
| Sepsis, septic | (1) is a term that indicated bacterial contamination. Blood can become (2). |
| Asepsis | refers to the absence of bacteria. |
| degerming. | Mechanically removing (scrubbing) microorganisms from a limited area, such as the surface of the skin prior to an injection is called |
| Sanitation | refers a treatment that lowers microbial counts to safe levels. When you put your dishes in the dishwasher they are cleaned and ----. |
| A chemical that kills microbes is a | germicide (biocides). |
| A chemical that kills fungi is a | fungicide. |
| A chemical or technique that slows the growth of bacteria is a | bacteriostatic agent. |
| microbes die at a ---- rate | microbes --- at a constant rate (ie they --- by a fixed percent per minute) |
| Things that afffect death of microbes | number of them (more means longer); environment (antimicrobials work better in warm solutions); exposure time (needs to be longer if more microbes or if have endospores etc) |
| porins | protein pores in outer membrane. |
| prions | infective proteins, eg mad cow disease. |
| Thermal death point (TDP) | Lowest temperature where all microorganisms can be killed in 10 minutes. |
| Thermal death time (TDT) | The minimum length of time for all bacteria of that species to die at a given temperature. This time changes for different temperatures. |
| Decimal reduction rate (DRT) | The time, in minutes, in which 90% of the bacteria in a sample are killed. |
| An autoclave | uses steam under pressure to increase the temperature for sterilization. |
| Pasteurization | This process uses mild heating to kill pathogenic microbes and lower the total number of microbes, but not affect the taste of the food. |
| dry heat - | used to sterilize equipment, such as with a bunsen burner (flaming). |
| hot air sterilization | requires placing an item in an oven (eg, 170C for 2 hrs) |
| Refrigeration as microbe control is | bacteriostatic form of controlling microbes with temperature. |
| desiccation | absence of water is bacteriostatic; this is called... |
| microwaves | type of radiation that doesn't harm microorganisms. |
| ionizing radiation | high energy radiation (gamma, x) hydroxyl radicals form; sterilize certain foods and medical supplies; |
| nonionizing radiation | lower energy, such as UV; damages DNA; used to disinfect hospital rooms and medical equipment. |
| factors to consider whent testing disinfectants: concentration composition contact | |
| Use-dilution test | Metal rings are coated with three microbes, usually Salmonella choleraesius, Staphylococcus aureus, and Pseudomonas aeruginosa. Different version of this test can examine the effectiveness of disinfectants on endospores, Mycobacteria, and fungi. These rin |
| Disk-diffusion method | in the --- method, A filter paper disk is saturated with a disinfectant (or an antibiotic) and is place on an agar plate containing a lawn of a particular microorganism. If the disinfectant works, a clear zone will form around the disk. |
| phenol, eg O-phenylphenol | The action of these compounds (1) is to disrupt the plasma membranes of microbes, and the cell walls of mycobacteria. They are used to disinfect complex substances that contain organic compounds (i.e. pus, feces). A good example is (2), found in Lysol. |
| bisphenols | composed of two phenolic groups. |
| example of bisphenols | triclosan |
| biguanides | disinfectants used on skin and mucous membranes, such as chloroheidine which blocks lipid synthesis in membranes of microbes |
| halogens | chlorine and iodine - iodine blocks protien synth of plasma membr. chlorine makes hypochlorous acid in water which oxidizes cellualr components. |
| alcohols | eg isopropanol and ethanol - kill veg cells, not endosp or nonenv viruses; denatures proteins and dissolves lipids; degerms. |
| heavy metals | germicidal effect by oligodynamic action, denature proteins. |
| Quaternary Ammonium Compounds (Quats) | These are cationic detergents, meaning that they contain a positively charged ion. This cation is related to the ammonium ion (NH4+). These destroy Gram positive cells, fungi, amoeba, and enveloped viruses effectively. These LIKELY DISRUPT THE PLASMA MEM |
| Aldehydes- | These are probably some of the best antimicrobials. Examples are formaldehyde and gluteraldehyde. These function to inactivate proteins in bacteria and viruses. |
| Peroxygens | These contain reactive oxygen species that oxidize cellular components. one of these can be used to destroy bacteria faster than the bacterial cell’s superoxide dismutase and catalase can inactivate it. |
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