Microbiology Test 3
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- What is oxidative phosphorylation?
- Making ATP energy from the protonmotive force.
- The protonmotive force works as...
- an electrochemical gradient.
- Describe the conditions in the periplasmic space.
- Acidic and Positively Charged
- Why is the electrochemical gradient a source of potential energy?
- H+ cannot diffuse through the membrane.
- Who won the Nobel Praice for oxidative phosphorylation chemiosmosis work?
- Peter Mitchell
- What does allow the protons into the cell?
- ATP synthase and transmembrane proteins.
- What two things does ATP synthase do?
- Uses energy from H+ moving down electrochemical gradient and phosphorylates ADP.
- What is the electron transport chain?
- A series of electron carriers in the cell memebrane.
- What does the electron transport chain do?
- Oxidizes coenzymes.
- What is the first carrier in the electron transport chain?
- NADH dehydrogenase.
- What happens to NADH and the first carrier in the electron transport chain?
- NADH is oxidized to NAD+ and the first carrier is reduced.
- What does NADH dehydrogenase do?
- Reduces the next carrier.
- What is the second carrier?
- Flavin mononucleotide.
- What else does NADH dehydrogenase do?
- pumps H+ into the periplasmic space.
- What happens to the electrons?
- They pass through the electron transport chain.
- What is the final electron acceptor?
- Oxygen.
- What happens to the H+ after re-entering the cell?
- It binds with the final electron acceptor (fea), oxygen to form water.
- What are often the final electron carriers in the electron transport chain?
- Cytochromes
- If cytochrome C is present, what happens?
- Cytochrome oxidase catalyzes cytochrome C oxidation and oxygen reduction.
- What does the oxidase test for?
- Cytochrome oxidase
- Why is the oxidase test useful?
- It differentiates between Gram - rods
- If oxidase test is positive what are you dealing with? Negative?
-
+ = Campylobactor (which causes food poisoning) and Pseudomonas.
- = Enterics. - Where do electrons come from for the electron transport chain?
- Catabolism
- What is catabolism?
- Break down of molecules to generate reducing energy.
- What four forms of producing energy are we comparing?
- Aerobic/anaerobic respiration, fermentation, and chemoautotrophy.
- What is aerobic respiration?
- The catabolism of polysaccharides and monosaccharides, proteins and lipids.
- What is the final electron acceptor of Aerobic respiration?
- Oxygen.
- What is the equation for the Aerobic respiration of glucose?
- C6H12O6 + 6O2 + 38ADP + 38PO4 --> 6CO2 + 6H2O + 38ATP
- What are the four steps of Aerobic Resipiration of Glucose?
- Glycolysis, Transition step, [TCA cycle, Kreb Cycle, and Citric Acid cycle], and the electron transport chain.
- What happens in Glycolysis?
- glucose is oxidized to pyruvate.
- What are the products of Gylcolysis and where does each come from?
- 2 ATP (2 used, 4 produced) during substrate level phosphorylation, NADH during the electron transport chain, and 2 pyruvates from each one glucose
- What occurs during the transition step of aerobic respiration?
- Pyruvic acid is oxidized to acetyl CoA.
- What does CoA stand for?
- Coenzyme A
- What are the products of the transition step and where do that come from?
- NADH from the electron transport chain and acetyl CoA from the Kreb Cycle.
- How many times does the TCA cycle repeat per one glucose?
- twice.
- What are the products of the TCA cycle and where do they come from?
- CO2, 2 ATP (one/turn of cycle)...GTP (guanosine triphosphate), and NADH and FADH2 (reducing energy) from the electron trasport chain
- What is the first step of fermentation?
- Glycolysis.
- What is the second step of fermentation?
- Oxidation of the NADH from glycolysis.
- What is the final electron/H+ acceptor in fermentation?
- Pyruvate or pyruvate derivative.
- How much energy is generated in fermentation as compared to Aerobic respiration?
- Less.
- Where does ATP formation occur in fermentation and in what amounts?
- Substrate level phosphorylation and in small amounts.
- How much oxygen is used during fermentation?
- Oxygen is not used, but maybe be present.
- What are the end products of fermentation?
- Gases, acids, and neutral products.
- What does the combination of products depend on?
- The fermentation pathway.
- What accounts for the energy difference between fermentation and aerobic respiration?
- Fermentation does not have the electron transport chain or the Kreb Cycle.
- What does the fermentation pathway of a microorganism during fermentation depend on?
- The type of microorganism.
- How do we detect carbohydrate fermentation?
- pH indicators, Durham tubes, Ex. Phenol-red lactose/glucose medium
- When detected carbohydrate fermentation, what would yellow mean?
- Acidic and that fermentation occurred.
- Name four fermentation pathways.
- Lactic Acid, Ethanolic, Mixed-Acid, and Butanediol fermentation.
- When does lactic acid fermentation occur?
- When muscles run out of oxygen.
- The end products of Lactic Acid fermentation are either:
- homolactic or heterolactic.
- What do homolactic and heterolactic mean?
- only lactic acid, and lactic acid + CO2, and EtOH respectively.
- Give examples of lactic acid fermentors:
- Streptococcus (dental cavities), Leuconostoc (Sauerkraut), Lactobacillus (normal human gut flora...digestion).
- What are the end products of Ethanolic fermentation?
- CO2 and EtOH
- Give an example of an Ethanolic fermentor.
- Saccaromyces cerevisiae (brewers and bakers yeast).
- Is yeast a pro or eukaryote.
- fungi...eukaryote
- What are the end products of Mixed-Acid fermentation?
- ethanol, CO2, and H2, and then acetic, succinic, formic, and/or lactic acids.
- What test can be used to distinguish Mixed-Acid fermentation?
- Methyl Red Test (MR)
- What will the results of an methyl red test look like?
- Because methyl red is a pH indicator, basic = yellow and acid = red (different from usual).
- What two species can the methyl red test distinguish between?
- E. coli (MR+) and Enterobacter aerogenes (MR-)
- What are the end products of Butanediol fermentation?
- Butanediol and CO2
- What test can be used to determine Butanediol fermentation?
- Voges-Proskauer test (VP test)
- What is the problem faced by the Voges-Proskauer test? The solution?
- Butanediol is neutral, so it tests rather for acetoin, a butanediol precursor.
- Between what two microorganisms does the Voges-Proskauer test distinguish?
- E. coli (VP-) and Enterobacter aerogenes (VP+).
- Enterobacter aerogens and E. coli are quite similar and live in a common environment, why would we want to distinguish between them?
- E. coli is a fecal coliform, a fecal pollution indicator in the environment that is the pathogenic Enteric that lives the longest outside the gut where as Enterobacter aerogenes is non-pathogenic and nothing to worry about.
- What is the final electron acceptor of anaerobic respiration?
- Something other than oxygen.
- What are 3 differences between anaerobic and aerobic respiration?
- different carriers in electron transport chain, more ATP produced in aerobic, the final electron acceptor is different.
- What type of reaction is anaerobic respiration?
- A reduction.
- What type of reduction is anaerobic respiration?
- Nitrate or sulfate reduction.
- Demonstrate a sulfate reduction.
- SO4 --> H2S
- What are the characteristics of the Sulfate Reduction products?
- Anoxic sediments that smell bad and are a black color.
- Demonstrate the denitrification reaction.
- NO3-->N2 (gas)
- What is the source of most atmospheric Nitrogen?
- Denirification of bacteria.
- What is the nitrogen cycle?
- N2 <--> nitrogen fixation by bacteria <--> NH4+ <--> NO2- <--> Nitrification by bacteria <--> NO3- (plants like this) <--> denitrification of bacteria <--> N2
- Show the reaction of Methanogenesis.
- acetate --> CH4 (a green house gas...absorbs heat).
- What type of organisms undergo mathanogenesis?
- Methanogens such as Archaea which are obligate anaerobes.