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Microbiology 481: Chapter 13

Terms in this set (29)

-_______ is the sum of all chemical processes carried out by living organisms
-_______ reactions that require energy to synthesize complex molecules
-_______ reactions that release energy by breaking complex molecules down
-Metabolism
-Anabolism
-Catabolism
-______ outside of the cell may require modification to enter the cytoplasm
-______ may require 'pre-digestion' to cross the outer membrane
-Metabolic substrates
-long-chain polymers
-We often think of ____ as the best chemical 'food', but plenty of microbes thrive on ______.
-_____ oxidize H2, H2S, NH3, Fe2+
-_____ convert light energy to chemical energy.
-sugar, inorganic compounds
-chemolithotrophs
-phototrophs
--oxygenic - express O2
--anoxygenic - no O2
Where do microbes obtain their carbon?
-____ obtain carbon from organic sources (e.g. glucose)
-____ obtain carbon from CO2

-How do these two classifications of microbes interact.
-heterotrophs
-autotrophs

-Autotrophs reduces CO2 produced by heterotrophs. When autotrophs reduce it, it makes it re-consumable for the heterotroph.
-Free energy change under actual conditions = ____
-_____ indicate that a reaction will release energy and move forward
-Gibbs Equation:
-∆G
-negative values
-∆G= ∆Go + RTln * [products/reactants]
-Metabolism seldom revolves around a ____.
-reactions are typically _____, with individual ΔG◦ values totaled to determine favorability.
-single reaction
-coupled
-If we look at the formation of ATP, we can see that its hydrolysis yields energy. How?
-Adding the phosphate to ADP involves a battle against steric hindrance & consumes energy (NEEDS MORE)
-ATP can drive reactions several ways. Name 3.
-Release of a single phosphate via hydrolysis
-Release of two phosphates via hydrolysis
-Transfer of a phosphate to an organic molecule like glucose
-Reduction and oxidation reactions involve _____ and can be ____.
-_____ describes the tendency to donate or accept electrons
-Describe the redox tower:
-electron transfers, coupled
-The reduction potential (Eo')
-Negative values likely to be an e- donor. Positive values likely to accept electrons. When putting two half reactions together consider the Eo' of each reaction. The more negative half rxn will donate e- from its more reduced molecule. Further apart each half reaction is on the tower, the more energetically favorable the reaction. This is becasue the ∆Eo value will be super negative... and ∆Eo proportional to ∆Go...and the more negative ∆Go, the more energetically favorable the reaction.
-If an electron/proton carrier serves as redox intermediate, a ____ Eo value means the e- donor was an ____ e- donor
-negative, effective
-_____ can be charged with both a proton and an electron (highly reduced)
-This molecule's energy value ____ as it is ___.
-This molecules _____ state plays a critical role in the ETC
-NAD+
-rises, reduced
-reduced
-____ supplies the ____ with electrons and protons which are separated in the membranes
-As electrons flow, _____ (from carriers and H2O) are pushed to one side.
-electron flow across the membrane drives ___ production
-NADH, ETC
-protons
-ATP
-Enzyme activity is defined by _____ properties.
-some enzymes are active (correct conformation) only when their _____ site is occupied. This site allows for regulation.
-3-dimensional
-allosteric
-____ values only tell us that the reaction is energetically favorable but little else.
- Having a _____ value doesn't just mean the reaction will occur fast. It may need some help for the rxn to happen faster.
-_____ perform the 'heavy lifting' by bringing substrates together in the correct orientation, ____ the energy of activation
-ΔG◦
- -ΔG◦
-enzymes, reducing
-Catabolism of _____ to _____ can follow several different pathways
-This _____ is broken apart with generation of ATP and reduced carriers
-glucose, 3-C pyruvate
-glucose
-_____ a common starting point for metabolism, whether respiration or fermentation is used.
-there are other metabolic pathways that break down ______ , and it isn't always coupled to aerobic respiration
-Glycolysisis
-glucose
-The Entner-Doudoroff Pathway also metabolizes glucose but with fewer steps. Describe it:
-The ED pathway for glucose metabolism generates less ATP (only 1 ATP consumed but net gain is only 1 ATP) but produces NADPH.
-NADPH is used for amino acid biosynthesis (and for photosynthesis)
-ED represents a balance between the need for energy and the need to build biomass
-The Pentose Phosphate Pathway also metabolizes glucose. When would this pathway be beneficial. Describe it:
-The pentose phosphate pathway is useful when 5-C sugars are needed
-pentoses are formed when CO2 is stripped from glucose
-The pentose phosphate pathway relies on the oxidation of glucose to ribulose5-phosphate
-In the absence of oxygen, products from glycolysis may enter _____ pathways
-recall that glycolysis only nets _____ plus _____. In the absence of a terminal electron acceptor, those _____ have to go somewhere.
-fermentation
-2 ATP, NADH/NADPH, protons
-During ______, organic substrates serve as both electron donor and electron acceptor.
-Fermenters share glycolytic catabolism of _____ but differ in terms of _____.
-fermentation
-6-c sugars, byproducts
-_____ is a 2 step process where pyruvic acid breaks down to acetaldehyde and finally to ethanol
-Alcoholic fermentation
-Some microorganisms rely upon ______ to metabolize _____, which causes pH to _____.
-others will produce ____ via an ____ intermediate
-mixed acid fermentation, glucose, drop
-2,3 butanediol, acetoin
-_____ and ____ tests distinguish between mixed acid fermenters and butanediol producers

-Give two details:

-Describe + and - results
-The Methyl Red, Voges Proskauer

--pH indicator (MR) measures acid production
--α-naphthol and KOH (VP) added to look for acetoin production

---_____
-Aerobes and anaerobes use the same pathways up to the point of _____ production
-Krebs Cycle produces _____ before pyruvate can enter Krebs, a _____ has to be stripped away (decarboxylation)
-pyruvate
-NADH and FADH2, carbon
-_______ includes reactions where hydrogen atoms are removed and electrons are transferred to coenzymes (electron carriers)

-This cycle does not operate under _______. Why?
-The Krebs cycle
-fermentation conditions
-because it needs plenty of FAD/NAD
-The Krebs cycle metabolizes _______
-In prokaryotes - occurs in ____
-In eukaryotes - occurs in ____
-a two-carbon acetyl group to CO2 and H2O
-cytoplasm
-mitochondria
-Krebs Cycle plays major role in respiration but also produces important intermediates for _____.

-Name and briefly discuss 3 important intermediates:
-biosynthesis
--α-ketoglutarate - amino acid synthesis
--oxaloacetate - can be converted to PEP (glucose synthesis)
--succinyl CoA - assembly of cytochromes
-However, if intermediates are siphoned off for biosynthesis, the Krebs Cycle may be _____.
-If oxaloacetate or succinate are used for biosynthesis, _____ can be produced to restore the flow. This is called the ______.
-"starved"
-glyoxylate, Glyoxylate Cycle
-Name Key events in the Krebs cycle:

-Give a brief overview:
--oxidation of carbon
--transfer of electrons to coenzymes
--substrate-level energy capture

-for each acetyl group, 2 molecules of CO2 arise, 4 pairs of electrons transferred to coenzymes, and energy captured in guanosine triphosphate(GDP + Pi GTP) GTP looks a lot like ATP!
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