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78 Cards in this Set
- Front
- Back
each yeast organism is composed of how many eukaryotic cells?
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one, they are unicellular
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what shape are yeast cells/
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oval/spherical
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yeasts are how many times larger than bacteria?
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5-10 times larger
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yeasts produce asexually by a process called what?
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budding (parent cell is a bud)
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yeast can also reproduce sexually. the sexual spores are called what?
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ascospores
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the medium used to grow yeast and molds is called what?
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sabouraud dextrose ogar
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sabouraud dextrose ogar contains lots of _______ and ______
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glucose and peptone
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yeasts are ________ anaerobic
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faculatively
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with oxygen yeasts use carbs to break down into carbon dioxide and ____
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water
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without oxygen yeasts use carbs to break down into carbon dioxide and ____
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ethanol
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yeasts have beneficial uses such as what?
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making bread and alcohol fermentation
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the scientific name of the type of yeast we looked at in lab is called ________ ___________
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saccharomyces cerevisiae
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molds are multicellular and ________ fungi
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filamentous
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the macroscopic aggregation of mold cells is called a _____
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thallus
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the thallus contains long filaments of cells joined together which are called _______
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mycelium
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each strand of mycelium is called a ____
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hypha
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there are 3 types of hyphae called what/
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vegetative, reproductive and rhizoidae
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what are vegetative hyphae?
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hyphae grow on the surface of culture media
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reproductive hyphae grows where?
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grows upwards and bear the asexual reproductive spores
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rhizoidal hyphae grows where?
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below the surface of the culture media and help anchor the mold in place
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if the hyphae have crosswalls, the crosswalls are called ______
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septums
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if there are septums (crosswalls) in the hyphae the hyphae is said to be _______
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septate hyphae
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if the hyphae have no crosswalls then the hyphae is referred to as ______
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eoenocytic hyphae
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hyphae grow by elongation at the ________
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tip
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five of the asexual spores are called what?
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athropsores, chlamydospores, sporangispores, conidiospores and blastospores
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3 types of sexual spores?
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zygospore, ascospore, basidiospore
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what type of mold was rhizpus on the sabourand dextrose agar medium?
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sporangiospores
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What is the difference between vegetative and aerial mycelia?
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Vegetative Mycelia does not give rise to spores.
Aerial mycelia gives rise to spores. Vegatiative is the part that is actually in 'physical' contact with whatever the fungi (us) is feeding on. It is the part that 'anchors' and absorbs nutrients. Aerial is the part that produces ASEXUAL spores |
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can bacteriological media be used for the cultivation of molds?
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yes sabouraud agar us a solid growth medium used for cultivation of fungi
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in the common bread-mold life cycle, what do the plus and minus signs mean
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different strains
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why arent molds streaked for isolation?
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molds do not produce distinguishable individual colonies the way bacteria do. They produce masses of hyphae called mycelia.
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are rhizopus hyphae coencytic or septic?
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nonseptate coenocytic
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describe the fruiting body of the mold aspergillus niger
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conidiospores: numerous short lengths of narrow hyphae with short chains of spores
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describe the fruiting body of penicillium
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conidiospore
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why are yeast colonies bigger than bacterial colonies?
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Yeasts reproduce by budding -- the cell wall projects outward to form a new daughter cell that eventually pinches off from the mother cell. Some may not separate entirely while budding, forming chains of unseparated yeast cells
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why do yeasts generally have to be cultured for longer periods of time than bacteria?
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They can be harder to detect and harder to control than bacteria
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why is sabouraud dextrose agar used to cultivate yeasts?
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it uses peptone as its protein and dextrose as the carbohydrate for nourishment. bacterial suppression occurs due to the low pH
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what are coliforms?
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rod-shaped Gram-negative non-spore forming organisms that ferment lactose with the production of acid and gas when incubated at 35° within 48 hours
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coliforms are ________ anaerobic
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faculatively
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why are coliforms selected as the indicator of water potability?
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coliforms survive in water and can detect feces. if they are present that means poo is in the water
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does a positive presumative test indicate that water is potable?
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if gas is in the tube then water is not potable
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why is the MPN test qualitative and not quantitative?
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we arent counting individual bacteria, only guessing
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what is the function of lactose broth in the MPN test
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it ferments lactose with gas formation within 48 hours
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what is the function of levines EMB or LES endo agar in the MPN test
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used to indidate if coliforms are present. it will show a metallic green
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what is the function of the tsa slant in the MPN test
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used to do the gram stain
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what is the function of gram stain in the MPN test
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used for looking for negative rods
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what does a metallic green sheen indicate on an EMB plate?
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coliforms are present
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name some bacterial diseases that can be transmitted by polluted water and what causes them
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shigella- dysentary
salmonella typhi- typhoid fever e.coli- diarrhea, urinary tract infection proteus-urinary tract infection pseudomonas- ear infections |
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how can coliforms in water be detected?
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by a statistical estimation called the most probable number test
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the MPN test is divided into 3 parts. Name them
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presumptive, confirmed and completed tests
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in the MPN test, what happens in the presumptive test/
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dilutions from the water sample are added to lactose. after 24 hours one looks for bacteria capable of fermenting lactose with gas production (coliforms)
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in the MPN test, what happens in the confirmed test?
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one transfers materials from the highest dilution of the lactose broth tubes that showed gas production into brilliant green lactose bile broth
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in the MPN test, what happens in the completed test?
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a sample from the positive brilliant green lactose bile broth is streaked onto a levines EMB. coliforms of the plate are then inoculated into a brilliant green broth and onto a nutrient agar slant
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On levines EMB plates what happens to coliforms?
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coliforms produce small colonies with dark centers
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in the completed test, the end result involves what?>
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a gram negative non sporing isolated bacterium.
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in the confirmed test of the MPN test, the formation of any gas at any time indicates what?
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a positive confirmed test
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what is a complete virus particle?
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virion
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bacteriophages grow and reproduce within _____
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bacteria
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one would expect to find bacteriophages when a large group of ______ is present
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bacteria
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because the concentration of bacteriophages specific for a particular host may be relatively low, the first step in the isolation procedure is an _______
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enrichment step
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when the sample is incubated with a population of the proper host, phages specific for that bacterium will ____________ in number
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multiply greatly
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phages are easier to isolate when they are present in _____ numbers
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greater
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membrane filtration serves to remove ______ and most __________
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cell debris and most bacteria
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any bacteria left over from membrane filtration can be killed and lysed by ________
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chloroform
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what is the double layered culture technique?
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indivdual viruses are isolated by mixing a small amount of filtrate with a young culture of the host bacterium and then spreadng the mixture out on the surface of a petri plate with the nutrient agar
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in practice, the viruses and bacteria are mixed with a dilute agar medium which is the ___ agar and then poured in a thin layer of the surface of the ___ agar
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top, base
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when the top agar of the double layered culture hardens then the bacteria are _______
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immobilized
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whenever a virus particle is present in th agar, it will infect an adjacent bacterial cell, reproduce and _____ its host cell
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lyse
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what is a clear area of lysed bacteria called?
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plaque
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ideally, each virus will produce _____ plaque
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one
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what is meant by a plaque-forming unit?
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one virus that infects a bacterial cell
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what are coliphages?
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viruses that infect E.coli
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determine the number of plaque forming units per ml in a sample that has been diluted 10^-8 and has give 200 plaque forming units when .5ml is placed.
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200/10^-8
200x 10^8 in .5 ml times by 2 to get the full 1 ml 400x10^8 in 1 ml. so the end product is 4.0x 10^10 in 1 ml |
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what effect does chloroform have on viruses? on bacteria?
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no effect on virus. they could care less
on bacteria, chloroform can lyse the cell membranes |
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bacteriophage are in the t ___ family
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even
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what are t4
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T4 is a bacteriophage that infects E. coli bacteria. Its DNA has an icosahedral head with protein and dna in he center and has 6 tails
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what is a coliphage?
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a type of bacteriophage that infects Escherichia coli
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what are capsids?
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the protein shell of a virus
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