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169 Cards in this Set
- Front
- Back
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What are the two themes that microbiology revolve around?
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a) understanding basic life processes
b) applying that understanding to benefit humans |
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Are microorganisms the oldest form of life?
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yes
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What are the 4 macromolecules
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proteins,lipids, carbohydrates, nucleic acids
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Why is the cell considered an open system
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because cells can take nutrients from the environments, transform them and release the waste into the environment
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Why are cells considered machines?
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they carry out chemical transformations
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Why are cells considered coding devices?
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store/process info that's passed onto offspring (via DNA)
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What was the first self-replicating entity?
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microbes/RNA??
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global estimate of microbial cells
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5e30
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why do microbes have antibiotics?
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to protect themselves from other microbes
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Who was the first person to describe microbes and coin the term cell?
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Robert Hooke (1600s)
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In the 1600s, who was the first person to describe bacteria?
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Anton van Leeuwenhoek
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In the 1800s who founded the field of bacteriology and discovered the bacterial endospores?
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Ferdinand Cohn
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In the 1800s, what did Louis Pasteur accomplish?
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a)discovered that living organism discriminate between optical isomers
b)proved alcohol fermentation was a biological process c) disproved spontaneous generation theory d)discovered the vaccines for Fowl Cholera, anthrax and rabies |
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In the 1800s what did Robert Koch accomplish?
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-demonstrated link between microbes/infectious diseases
-Koch's postulates -developed techniques for obtaining pure cultures of microbes |
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What are Koch's Postulates?
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1) suspected pathogenic organism must be present in all cases of the disease and absent from healthy animals
2)The suspected organism should be grown in pure culture 3)Cells in pure culture should cause the disease in healthy animals 4) the organism should be reisolated and shown to be the same as the original |
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Give 4 examples of bacteria that cannot be grown in pure culture
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chalmydia, rickettsias, cholera and syphillis
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In what time period did Martinus Beijerinck do most of his work? What 3 things is he known for?
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-late 1800s - early 1900s
1. enrichment culture technique 2. nitrogen fixation 3. filtered out viruses from bacteria |
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Define resolution
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the ability to distinguish two adjacent objects as separate and distinct
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resolution is determined by what property of light?
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wavelength of the light used
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what is the resolution limit for a light microscope?
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0.2 micrometers
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name 4 types of light microscopy discussed
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1.bright-field
2.phase-contrast 3.dark-field 4.fluorescence |
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Which microscope is required to look at intact cells under relatively low magnifications?
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light microscope
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What type of stain is the Gram stain?
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differential
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What color are gram-positive bacteria?
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purple
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What color are gram-negative bacteria?
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pink
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Describe phase contrast microscopy
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-contrast without a stain
-live samples -dark cells/light background |
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describe dark-field microscopy
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-light reaches specimens from the side
-light reaching the lens is scattered by the specimen -light image/dark background -excellent for observing motility |
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Which microscope would you use if you wanted to see motility?
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dark-field microscope
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which microscope has a light image on a dark background?
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dark-field microscope
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Which microscope would you use if you wanted to see depth/3-D?
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Differential Interference Contrast
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Name 3 structures that you would use a Differential Interference Contrast microscope to view.
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Vacuoles
Endospores Granules |
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If a structure that did not show up when a bright-field microscope was used suddenly showed up, what microscope are you using?
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Differential interference Contrast
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If you wanted to enumerate bacteria in natural samples. which microscope would you use?
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fluorescence
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If you had a computer-generated imaged based on data, which microscope was most likely used?
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Atomic Force Microscope
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Which microscope would you use if you wanted a computer generated 3D image?
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Confocal scanning laser microscope
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What is the resolution for a confocal scanning laser microscope?
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0.1 micrometer
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Name the two types of electron microscopes.
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Scanning Electron Microscope
Transmission Electron Microscope |
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Which electron microscope is best for 3-D images?
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SEM
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If my specimen was very large, which electron microscope would I use?
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SEM
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If my sample was very very thin and I wanted to view structures at the molecular level, which microscope would I use?
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Transmission Electron Microscope
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Although prokaryotes do not have a nucleus, DNA aggregates to form a ______ region
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nucleoid
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In prokaryotes, the "housekeeping genes" are most likely in plasmids. True/False
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false
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Name the three characteristics of eukaryotic DNA discussed.
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-proteins that help DNA fold
-usually more than one chromosome (linear) -usually two copies of each chromosome |
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Name the two characteristics of prokaryotic DNA discussed
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-circular DNA molecules that aggregate to a nucleiod region
-sometimes small amounts of extrachromosomal DNA called plasmids |
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What type of genes are excellent for determining phylogeny?
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rRNA
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If only 1% of bacteria have been typed, how can we know the total number of bacteria?
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ribosomal genes; humans have 18s whereas bacteria have 16s
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What are the 3 domains that we've defined by comparative rRNA sequencing
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-Bacteria
-Archaea -Eukarya |
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Name the group of organisms who derive energy from the oxidation of organic molecules
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Chemoorganotrophs
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Name the group of organisms who derive energy from oxidation or inorganic materials
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chemolithotrophs
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Chemolithotrophy is only found in prokaryotes or eukaryotes
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prokaryotes
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Name three characteristics of Phototrophs
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-anoxygenic photosynthesis does not produce oxygen
-pigments allow organisms to use light as energy -oxygenic photosynthesis produces oxygen |
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True or false: all cells require carbon as a major nutrient
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true
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Name two characteristics of autotrophs.
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-use carbon dioxide as their carbon source
-AKA producers |
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Name two characteristics of heterotrophs.
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-require one or more organic molecules as a carbon source
-feed directly on autotrophs or live off of products produced by autotrohs |
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True or false: Extremophiles usually infect humans
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false
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True/false: All known pathogenic prokaryotes are Bacteria
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true
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Name two genii of Bacteria that form endospores
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Bacillus (anthracis/cereus) and Clostridia (botulinum/tetani)
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Which bacteria were responsible for oxygenating the atmosphere by using light as energy
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filamentous cyanobacteria
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Name the bacteria that's extremely resistant to radioactivity
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Deinococcus radiodurans
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Name the two phyla of the domain Archaea
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Euryarchaeota
Crenarchaeota |
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organisms of the phyla Crenarchaeota are ____philes
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hyperthermophiles
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Name 3 groups of organism in the phyla Euryarchaeota
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Methanogens, extreme halophiles, thermoacidophiles
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eukaryotic microorganisms are collectively known as
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protists
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Name the 3 major groups of protists discussed
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slime molds
algae protozoa |
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if an organism secreted digestive enzymes into its environment to eat, what type of eukaryote is it?
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fungi
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True/False: Yeasts are fungi
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true
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Describe the mutualistic relationship between fungi and cyanobacteria and algae/fungi
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cyanobacteria/algae (phototrophic) are the primary producer and the fungi acts as an anchor and protection from the environment
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Define metabolism
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sum total of all chemical reactions in a cell
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Differentiate catabolic and anabolic reactions
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catabolic-metabolic reactions that release energy
anabolic- metabolic reactions that require energy |
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Define nutrients
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monomers that the cell needs or growth
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Define macronutrients and name the 3 discussed in class
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nutrients that are required in large amounts (C,H,O)
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Micronutrients. Frequently used as ____ _____
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nutrients that are required in trace amounts. enzyme cofactors
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What are 4 examples of growth factors?
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-vitamins
-amino acids -purines -pyrimidines |
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Give the 4 bullets on the slide for the cofactor iron
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-used in cellular respiration
-anoxic envmt: ferrous (soluble) -oxic envmt: ferric (insoluble) -cell produces siderophores to retrieve iron |
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Give an example of a cofactor
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iron
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What selective/differential media would you use to differentiate S. aureus or S. epidermis? Why?
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Mannitol Salt Agar - salt inhibits non-staphlyococcus bacteria and when S. aureus grows it ferments creating acid which makes the color change from pink to yellow. S. epidermis does not ferment.
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Min C, D and E play what role in cell division?
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Min C and D are associated with the poles of the cells. E goes back and forth between both poles. All three inhibit FtsZ from binding and ultimately help center FtsZ
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What protein is essential for cell division in all prokaryotes?
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filamentous temperature sensitive proteins (Fts)
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How do the Fts proteins interact to form the divisome?
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Min(C,D,E) facilitate location of FtsZ which forms the ring around the cell
-ZipA anchors the ring to the cytoplasmic membrane FtsA attaches the ring to the membrane and recruits divisome proteins -FtsK facilitates separation of chromosomes to daughter cells |
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What is the major shape-determining factor in prokaryotes?
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murein binding (MreB)
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4 characteristics of mreB
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-forms simple cytoskeleton
-forms spiral shaped bands beneath the cytoplasmic membrane -not in coccus-shaped bacteria -localizes synthesis of new peptidoglycan and other cell wall components to specific locations along rod-shaped cell |
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is mreB shape-determining?
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no
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shape determination relies on what two components
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mreB and crescentin
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Two main ways to perform plate counts
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1.spread plate
2.pour plate method |
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What's the range of bacteria that you want when you do a spread-plate method?
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30-300
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How do you calculate cell count via serial dilution calculation?
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cfu x dilution factor
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What is the most plentiful bacteria in the gut?
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bacteroides
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What was the Great Plate Anomaly?
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direct microscopic counts of natural samples often revealed too many organisms than were recoverable on plates of any given culture medium
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How do you explain the great plate anomaly?
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not all cells were living, some bacteria don't grow on plates very well, plate conditions weren't right for some bacteria...all kinds of inaccurate
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Name a problem with turbidity measurements.
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no way to distinguish between living and dead cells
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Why do temperature and growth rate curves lean to the right?
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because enzymatic activity increases with temperature until the enzymes denature...
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Give an example of a psychrotolerant bacteria
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Listeria monocytogenes
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Why are most pathogenic bacteria mesophiles?
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because mesophiles have optimal enzymatic activity at around our body temp (37)
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How can fevers benefit humans?
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since most pathogenic bacteria are mesophiles, their enzymes probably denature at higher temperatures than our body heat (ie fever)
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organisms with the highest temperature optima are archaea/bacteria?
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archaea
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What modifications to cytoplasmic membranes would ensure heat stability?
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Bacteria: lipids rich in saturated fatty acids
Archaea: lipid monolayer |
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What was the example of the enzyme from hyperthermophiles?
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Taq polymerase. withstands the heating process used in PCR
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most organisms grow best between what pH?
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6-8 (neutrophiles)
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Name two examples of mechanisms for combating with low water activity in surrounding environment
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-pump ions into cell from environment
-synthesize/concentration of organic solutes |
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what organisms can live with or without oxygen?
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facultative
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which organisms can tolerate oxygen and grow in its presence despite not being able to use it
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aerotolerant anaerobe
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which organisms can survive at low concentrations of oxygen
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microaerophiles
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The prefix staphylo implies what formation?
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cluster
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The prefix strepto implies what formation?
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chain
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Name the cell morphology that resembles a cylindrical shape
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rod
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name the cell morphology that resembles a sphere
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coccus
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name the cell morphology that resembles a spiral
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spirochete
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name the cell morphology that resembles a twisted rod
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sprillum/spirilla
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Small cells have higher/lower surface to volume ratios
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higher
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Give 2 advantages of a high surface/volume ratio
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-greater nutrient exchange per unit cell volume
-grow faster |
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Why is the cytoplasmic membrane highly selective?
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enables concentration of speciic metabolites and excretion of waste products
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T/F Variation in the chemical forms of the cytoplasmic membrane are due to the groups attached to the glycerol backbone.
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true
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What two ions are associated with the cytoplasmic membrane and what do they do?
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Ca2+ and Mg2+ help stabilize the membrane by forming ionic bonds with negative charges on the phospholipids
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Name two exceptions of bacteria that have sterols instead of hopanoids
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Mycoplasmas and methanotrophic bacteria
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Why are archaeal cytoplasmic membranes lipid monolayers?
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in the diglycerol tetraether lipid, the 2 phytanyl side chains on each glycerol form covalent links
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what transport protein on the cytoplasmic membrane facilitates water movement?
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aquaporins
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why are transport proteins necessary?
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-only small, nonpolar molecules can diffuse across the membrane
-the concentration of solutes outside the membrane is often too low for the cell to survive off of |
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What are the two major lipids of archaeal cytoplasmic membranes?
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-glycerol diethers
-diglycerol tetraethers |
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Describe the eukaryotic/bacterial phospholipid
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fatty-acid and D-glycerol are linked by ester linkages, forming a lipid bilayer
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Do archaeal lipids have fatty acids?
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no, instead there are isoprenes
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Describe the archaeal phospholipid
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isoprene and L-glycerol are linked by ether linkages
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Describe the 3 major functions of the cytoplasmic membrane
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1. permeability layer (hydrophobic interior is a tight barrier to diffusion)
2. anchor for proteins (that catalyze bioenergetic reactions) 3. energetically charged form via proton motive force which drives energy requiring functions |
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What is the saturation effect?
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if concentrations of a solute outside the cell are high enough (saturated), the cell's uptake increases
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Describe the ABC transport system
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ATP-Binding Cassette;
requires 3 components: 1. substrate binding protein 2. membrane integrate protein 3. ATP-hydrolyzing protein |
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Describe the simple transport system.
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driven by the energy in the proton motive force...
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Describe the group translocation transport system
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chemical modification of the substance is driven by phosphoenolpyruvate
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the group translocation system is driven by
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phosphoenolpyruvate
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Describe the phosphotransferase system
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1. group translocation
2. 5 proteins transport fructose, mannose and glucose 3. (de)phosphorylation cascae results in sugar being phosphorylated during the transport event 4. energy for the system comes from phosphoenolpyruvate |
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What were the two types of protein export discussed?
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Sec translocase system
Type III secretion system |
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Describe the sec translocase system
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7 protein system that exports proteins and inserts integral membrane proteins into the membrane
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describe the Type III secretion system
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common in pathogenic bacteria and secreted protein is translocated directly into host
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The cell wall of bacteria is made of?
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peptidoglycan
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T/F Peptidoglycan is only found in bacteria
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true
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What is the specific flagella antigen
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H-antigen
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What purpose does peptidoglycan serve and what is it composed of?
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-purpose: strength
-polysaccharide composed of a)NAM and NAG b)aa c)lysine/diaminopimelic acid |
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all gram-negative and some gram-positive species of bacteria contain which amino acid?
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diaminopimelic acid (DAP)
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most gram-positive bacteria have what aa?
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lysine
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The sugars of peptidoglycan are connected by what type of linkages?
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NAM and NAG are connected by beta-1,4 linkages
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True/False: peptide chemistry of peptidoglycan varies
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true
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True/False: the backbone of peptidoglycan (NAM-NAG) is always the same
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true
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If teichoic acid is found in the cell wall of a bacterium, is it gram-negative or -positive?
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positive
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What enzyme is responsible for linking the peptides to NAM?
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transpeptidase
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True/False: Penicillin binds to the enzyme transpeptidase
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true
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What happens when penicillin binds to transpeptidase?
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the formation of peptide-cross links is inhibited
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What does lysozyme do?
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lysozyme degrades the beta-1,4 linkages between the NAM and NAG sugars, breaking an already-formed cell wall
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What role do teichoic acids play in the negative charge of the cell surface?
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teichoic acids are negatively charged, so they bind to Ca2+ and Mg2+
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what are the 3 components of LPS?
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O-polysaccharide
core-polysaccharide lipid A (endotoxin) |
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two prokaryotes that lack cell walls
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mycoplasmas and thermoplasa
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why is lysozyme ineffective on arachaea?
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no peptidoglycan, no beta-1,4 linkages to break
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Some archaea (methanogens) have a polysaccharide that is similar to peptidoglycan. Name it.
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pseudomurein
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Cell walls of arachaea are usually called:
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S-layers
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S-layers are a cell wall type of which domain?
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Archaea
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S-layers consist of what components?
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protein/glycoprotein
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what are the 4 characteristics capsule/slime layer?
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--made of polysaccharides
-anti-phagocytic...immune system evasion -help bacteria attach to surfaces -prevents dessication because of sugars |
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Describe how cavities form.
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-eat sugar
-bacteria make a slime layer/capsule out of the polysaccharide -bacterial activities cause fermentation -fermentation yields lactic acid, which lowers the pH -lower pH is an excellent de-calcifying environment-->cavities~ |
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What are filamentous protein structures called?
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fimbriae/pili
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which type of filamentous protein structures are involved in twitching motility?
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type IV pili
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how do pili/fimbriae enable organisms to stick to surfaces and form pellicles?
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specific adhesins which bind to specific sugars
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Name two carbon storage polymers
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PHB and glycogens
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What are 3 examples of cell inclusions?
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-Sulfur globules
-polyphosphates -magnetosomes |
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4 characteristics of gas vesicles
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-Gas vesicles are impermeable to water
-Buoyancy in planktonic cells -Function by deceasing cell density -Spindle-shaped structures made of protein |
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Spores are only present in some gram (+/-) bacteria?
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gram positive
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Name four differences between vegetative cells and spores
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-dipicolonic acid in spores is high for dehydration
-enzymatic activity is high in veg -SASP in spores act as dessicant and food -veg have mRNA |
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Name the 5 structural components of a bacterial spore
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Exosporium
Spore coat Core wall Cortex DNA |
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what are the 3 different arrangements of flagella
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peritrichous
polar lophotrichous |
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Concerning flagellated cells, which way do the flagella turn to go straight/tumble
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CCW/CW
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What are 3 differences between gliding motility and flagella motility?
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-gliding is slower
-fliding occurs along cell's axis -gliding requires solid surface contact |
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what were the 3 gliding motility mechanisms?
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-polysaccharide slime
-type IV pili -gliding-specific proteins |
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In chemotaxis, attractants and receptors are sensed by
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chemoreceptors
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