quiz 2 Flashcards
what mechanism do bacteria use to grow?
binary fission, Division of one cell to two daughter cells
what is generation time?
time required for one cell to form two or time required for a population to double in number, influenced by environment.
What is batch culture?
Organisms incubated in a flask or a tube with sterile media.
What is the Lag phase in broth culture?
Phase where cell numbers remain unchanged but cells have high metabolic activity, high levels of protein synthesis and cell composition. Acclimatization
What is the Log phase in broth culture?
population grows at maximum rate possible, exponential cell # increase
What is the stationery phase in broth culture?
individual cells grow very slowly, total cell number remains constant
What is the death phase in broth culture?
culture dies, cells die
Describe asymmetric division in sporulation.
Cell asymmetrically divides into large mother cell and smaller foreshore. Forespore is engulfed by mother cell, becoming the endospore.
What is the moth-endospore complex called in sporulation?
Mother-endospore complex is called the sporangium
What cell types often have sporulation?
Bacillus and clostridium
What are the morphologies for bacillus and clostridium?
gram positive, rod shaped, motile and long chain
What are key traits of bacillus?
obligate aerobe via respiration or facultative anaerobe via respiration or fermentation, catalase positive
What are key traits of clostridium?
obligate anaerobe that ferments, catalase negative, aeroduric
What does it mean for a bacteria to be an aeroduric anaerobe?
oxygen resistant even though requires anoxic conditions, can survived in prolonged oxygen but won’t reproduce
What is catalase? What is the catalase test?
catalase works with enzyme to protect cells against toxic species.
converts hydrogen peroxide to H2O and molecular O2. Found in aerobes and facultative anaerobes, catalase only expressed with oxygen exposure.
What are Pseudomonads?
rod shaped, gram negative proteobacteria, obligate respires that use oxygen as term e- acceptor. Have a positive oxidase test.
Can be pathogenic
Why is pseduomonads unusual?
Commonly used as bioremediation bc they rapidly metabolize and oxidize unusual compounds.
What is the oxidase test?
identifies cytochrome C. oxidase which the terminal oxidase in electron transport chain
-catalyzes the transfer of electrons from electron carrier to oxygen
-bacteria is oxidase negative when it does not use etc
micrococcus morphology
gram positive, diploid or tetras cocci, obligate aerobe
will have pink rim around purple body, catalase positive
staphylococcus morphology
gram positive, random and irregular cocci, facultative aerobe and acidic on glycerol
What is the terminology for negative, positive and positive w/gas test.
Negative if culture is yellow:NC
positive if pink color change: A
positive if pink with bubbles(fermentation): AG
describe the acetoin test
acetoin is metabolic intermediate when cells use the butanediol fermentation pathway to ferment glucose. in presence of potassium hydroxide, acetoin is converted to diacetyl, with the addition of creatine, the mixture turns dark red. Peptone broth is the source of creatine
What reaction is taking place in the nitrate reduction test
denitrification: Nitrate->nitrite-> N2 and ammonia, absence of nitrite is either bc we don’t have a nitrate reducer or that we have a nitrite reducer, so we made N2 and NH3
How do we determine the results of a nitrate reduction test?
If color after adding A+B->(+) results nitrate was converted to nitrite
if color after zinc added->negative result, organism did not convert nitrate
if no color change after zinc->(+) result, organism reduced nitrate to ammonia and N2
