Microbiology Lab Quiz #17

micro lab QUIZ #17 OIL RIG OXI dation IS loss of electrons reduction IS gain of electrons (that was a cuestion!!) living organisms obtain energy by removing electrons (oxidizing substrates) Oxianation reactions =energy. ex: glycolosis glucose oxidized pynene acid. For successful oxidation, there needs to be an electron acceptor that combines with the electrons that were removed and are now free. electron acceptors are reduced when they accept(add) electrons (011-RIG) Oxidation reduction reaction must always be paired T d reduction reaction. ex: photosynthesis carbon dioxide. reduced Fermentation: glucose is oxidized ,and organic acceptors. molecules found inside the cell, such electron as pynivic acceptor acid Serve is then as electron reduced into other compounds sud as The lactic acid. * ETC (electron transport chain) IS used in oxidative metabolism, or respiration atoms / monecules outside the cell serve respiration. as electron acceptors, - 02 -lons, IS the final electron acceptor m aerobic & In aerobic bactena, cytochromes in the plasma membrane carry electrons to 02. 4 types of bactenal cytoenromes exist cytochrome C IS one of them. I enzyme OXIMASE TEST identifies prescence of chicknome

Some bactena do 9 have cytochrome V. Dunngrespiration hydrogen atoms may combine T oxygen, forming hydngen peroxide (H2O2)- LETHAL TO CELL acrobic organisms usually produce catalase,to break hydrogen peroxide H2O and O2. CA TALASE TEST - anaerobic respiration - has other final electron accuptors other that O2. "an the ates" ex: (sulfate, carbonate, nitrate) - some bactena can also use organic electron acceptors some bactena reduce : nitrate nitrite. hihite nitrous oxide. nitrous oxide hitrogen gas. Nitrate Reduction Test nitrate broth (Intratebroth 0.1% nitiates potassium mirate) IS used to determine uses a buctenas ability to reduce Nitrites detected by adding 2 reagents: I 2 sulfanilic acid V (-) result. checked for prescence of nitrite by took adding place.) zinc (+) result = = 0 red color color change,remains change yellowich nitrate /coloriess (-) (which test IS would further confirm that Dreduction to red nitrate- - so If nitrate present = (+) Color change also!

If zinc nitrate or I nitrite IS present, indicate nitrogen 0 was color Teamca change IU -yellow V reduces nitrous oxide you will IV see gas bubble in burham tube . 0 nitrogen gas.

140 EXERCISE 17: RESPIRATION S Nitrate Nitrate reduced to T not Nitrite nitrogen B reduced produced gas nitrogen in nitrate nitrite NO3 NO2 N2 gas Ni Ni gasbubble. Hy St Ox Zir Growth dimethyl -a naphthylamine reagent A. (+) nltrite 1 sultanilic reagent acid (-)nitrite (-) nitrite 2 (+) ni7roger Ba Arregoons Nitrate Esc reagents Pse A & B zincreduces Lac nitrate red so red color (-)nitrite (+)for nitrate (1) nitrite (-Initrate (+)nitrogen gas Te add. Zinc dust Inoc Asep FIGURE 17.2 Nitrate test. Nitrate reagents A and B are added Plat to nitrate broth after incubation to determine nitrate reduction. If the broth turns red after the reagents are added, nitrate ion was reduced to nitrite ion. Zinc dust is added if no color change occurs. If the broth turns red, ni- PR trate ions are present. If nitrates were reduced to nitrous oxide or nitrogen gas, no color change occurs. If nitrates were reduced to nitrogen Ni+

gas should be visible in the Durham (inverted) tube (at arrows). vege gas, the 1. anaerobic respiration. . some bacterin