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Micro Final Unit 2
| Question | Answer |
|---|---|
| Where and how is ATP produced for aerobic respiration | 2 net ATP from glycolysis *cytoplasm* via slp, 2 ATP from krebs via slp, 32 from etc via ox-phosp *mitochondria* |
| Where and how is ATP produced for anaerobic respiration | glycolysis in the cytoplasm, etc ACROSS cell membrane produced, still can do ox-phos since this DOES NOT REQUIRE OXYGEN |
| Where and how is ATP produced for fermentation | *cytoplasm only SLP, electron acceptors can be inside OR outside the cell, electron carriers are recycled thanks to fermentation products |
| Where and how are electron carriers like NAD+/NADH recycled for anaerobic respiration | Anaerobic: cell membrane, uses different final electron acceptor |
| Where and how are electron carriers like NAD+/NADH recycled for aerobic respiration | mitochondrial inner membrane, ETC, donate H to ETC and regenerate NAD+ |
| nd how are electron carriers like NAD+/NADH recycled for fermentation | cytoplasm, convert pyruvate to byproduct, regenerate NAD+ |
| What is the terminal electron acceptor for aerobic respiration, anaerobic respiration, and fermentation | oxygen, other, pyruvate |
| Which process produces more ATP? Why? | aerobic respiration, Oxygen has the greatest difference from starting value on the electron tower |
| requirements for microbial survival and growth | Carbon, energy, electrons |
| Define and recognize the major nutritional types of microorganisms based on their energy source | energy is from chemical (chemo) or light (photo) |
| Define and recognize the major nutritional types of microorganisms based on their carbon source | organic (hetero) or CO2 (auto) |
| Define and recognize the major nutritional types of microorganisms based on their electron source | organic (organo) vs inorganic (litho) *rock eaters |
| concepts of free energy (G) and standard free energy change (delta G) | Free energy is the amount of disorder, standard free energy change can be positive or negative and indicates if the free energy increases or decreases |
| Distinguish between exergonic and endergonic chemical reactions and their relationship to delta G | Exergonic releases energy, negative delta G, endergonic requires energy so positive delta G |
| Explain the importance of ATP | Energy currency, the high energy bonds between negative Phosphate groups release energy when broken → this energy can do chemical work and mechanical work in bacterial cells Energy is needed for crucial reactions that run in the cell |
| Two classes of electron carriers | Coenzymes: move around freely (NAD+/NADP, FAD/FADH2) act as trucks picking up and dropping off electrons Prosthetic groups: stationary, embedded in membrane → electrons more from one to another |
| how NAD+/NADH and NADP+/NADPH carry electrons and their roles in metabolism | NAD+/NADH can move around freely because they are coenzymes, they are constantly recycled NAD+/NADH carriers electrons from glucose to ETC to produce ATP **catabolism |
| Compare and contrast aerobic respiration, anaerobic respiration, and fermentation in bacteria | Aerobic respiration: final electron acceptor is oxygen Anaerobic: final electron acceptor is not oxygen, different exogenous acceptor like NO3- or CO2 Fermentation: no ox-phos much less ATP produced, create end products to recycle electron carriers |
| Compare and contrast substrate level phosphorylation and oxidative phosphorylation | SLP: high energy bonds are broken down to release energy Ox-Phos: electron transport chain is used, create a proton motive force to run ATP synthase |
| Describe the location, organization, and functions of the electron transport chain in bacteria | Happens across plasma membrane Protons are pumped from cytoplasm to periplasmic space (space in between membrane and cell wall) Build up a proton gradient for ATP synthase, flagellar rotation, nutrient transport |
| Describe the organization and functions of the electron transport chain in aerobic respiration including its role in ATP production | Creates a proton gradient through a series of redox reactions |
| function of ATP synthase | Joins ADP with Pi using proton motive force (gradient that was established) |
| Know the functions of proton motive force and how it is established | Powers ATP synthase, established with electron transport chain and a series of redox reactions |
| aerobic catabolism (overview) | Split glucose to 2 pyruvates (+ 2 ATP + 2 NADH), convert pyruvate into acetyl Co-A (+ NADH) use this for Krebs cycle (+ ATP, + FADH2 + NADH). Electron carriers from krebs donate e- to ETC, move through membrane proteins to reach final electron acceptor |
| For aerobic respiration, explain where in the pathway atp is produced (glycolysis) | 2 net ATP via SLP, 2NAD+ → 2NADH |
| For aerobic respiration, explain where in the pathway atp is produced (pyruvate oxidation) | + 2 NADH (bridge step) |
| For aerobic respiration, explain where in the pathway atp is produced (Krebs/TCA) | 2 net ATP via SLP, 6 NADH, 2 FADH2 |
| For aerobic respiration, explain where in the pathway atp is produced (ETC) | 3 ATP from each NADH, 2 ATP from FADH2 via ox-phos |
| Describe the process of fermentation and the products | uses slp to generate ATP Electron acceptors inside/outside the cell, uses pyruvate from glycolysis to recycle NADH, this creates lactate. Converting pyruvate into acetaldehyde also recycles NADH and produces ethanol |
| function of fermentation | produce energy in absence of the etc and oxygen |
| What is meant by assimilative process? | building new cellular material, whatever is made during this process is kept and usually go towards making a new cell or growing the current cell Use energy, cells only do exactly what they need so these processes are tightly controlled |
| What is meant by Dissimilative process? | conserving energy so you can use it for assimilative processes Oxidation and reduction of compounds (sulfide reduction, nitrification) Processes done continuously + in excess, cell needs energy Electron acceptors/donors are used in HUGE amounts |
| What is autotrophy? | Usings CO2 as a Carbon source |
| What is phototrophy? | Using light as an energy source |
| What is the purpose of the light reactions and the light-independent dark reactions in photosynthesis? | Light reactions generate ATP and reducing power (electrons up the tower) Dark reactions reduce CO2 to use in cellular material |
| What is the difference between oxygenic and anoxygenic photosynthesis? What drives this difference? | (Z scheme) Oxygenic produced oxygen since water is the electron donor, (Cyclic) anoxygenic does not produce oxygen, it uses a different electron donor |
| Where would you find photosynthetic machinery in prokaryotic phototrophs (2 possibilities) | Membrane Chlorosomes |
| Describe anoxygenic photosynthesis in terms of electron flow. How is ATP generated? | Light excites the electrons in the reaction center, they fall down and flow in a circular fashion ATP is generated by ATP synthase, powered by a PMF created by falling electrons pumping protons across the membrane |
| How is NADH generated? | Reverse electron transport generates NADH |
| What is meant by cyclic photophosphorylation? What is meant by reverse electron flow? | The electrons are recycled and can be used over and over again, there is no net gain/loss. Reverse electron flow is pushing electrons up the tower using energy from light |
| Why is reverse electron flow necessary? | it converts weak electron donors into strong electron donors that will be good for reduction *Quinone pool was source of reducing power, but not enough power |
| Describe oxygenic photosynthesis in terms of electron flow. How is ATP generated? | Electrons are dumped onto carriers in the 1st rxn center, get excited, and fall eventually to the 2nd rxn center The e- are not cycled, it's a Z scheme, new e- are needed ATP is generated from 1st e- fall, fall from 1st rxn center to 2nd produces a PMF |
| How is NADH generated? | NADH is generated by the 2nd electron fall since the electrons act as a source of reducing power |
| What happens when oxygenic phototrophs perform anoxygenic photosynthesis? | Oxygen is shut off so photosystem 2 is shut off (it's dependent on oxygen) ATP is generated by falling e- from photosystem one, Z-scheme is abandoned and the organisms goes with cyclic phosphorylation *occurs when cyanobacteria need to nitrogen fixation |
| How does iron oxidation differ in acidic environments? Why? What are the impacts of this difference? | Microbes are acid tolerant/acidophiles process is run in excess, very few electrons present for a gradient to be produced and pump protons, ATP synthase has enough PMF for few ATP each time Fe is close to O on the electron tower under these conditions |
| How does iron oxidation differ in neutral environments? Why? What are the impacts of this difference? | NEUTRAL environment: microbes collect more energy each time they run a reaction since the electrons fall further and more ATP is made *does not have to run reaction as frequently |
| What happens to the ETC and PMF for iron oxidizers? | ETC is shorter in acidic conditions, best way for cells to deal is by maintaining a neutral pH inside the cytoplasm *natural proton gradient is formed |
| Does production of ATP “cost” energy in these organisms? Why or why not? | This requires work to maintain, the cell is constantly having the important H+ for ATP synthase that then has to pump out/use H+ |
| Does production of ATP “cost” energy in these organisms? Why or why not? part 2 | Producing ATP requires the cell to do lots of oxidation to create a PMF since energy is already used pushing electrons up the tower to create reducing power |
| What is nitrification? What are the two steps? | NH3 is oxidized to NO3- Ammonia oxidation, generative PMF with electron transport chain Reduction of oxygen, push out 2 protons, ox-phos generates ATP |
| Do microbes generally perform one or both steps? | Microbes will usually pair up and just do one step each, Nitrospira has been found to do both |
| How are acetogenesis and methanogenesis similar? | Both use CO2 as electron acceptor, Both use H2 as electron donor, Both are classically STRICT anaerobes, Both make ATP through ion motive force (proton or sodium) |
| How are acetogenesis and methanogenesis different? | Differences: end products and methanogens ONLY use ion motive force, acetogens can ALSO use SLP *acetogenesis → acetate *methanogenesis → methane |
| How do acetogens generate ATP? | Ox-phos and substrate level phosphorylation (woodljungdahl pathway) Reduce CO2 into acetyl-CoA, then use this to create acetate (this part generates ATP) |
| What is electron bifurcation? | Combo of 3 reactions, hydrogen donates electrons to hydrogenase, hydrogenase undergoes endergonic reaction to push electrons back up the electron tower (it gets the energy to do this from the reduction of NAD+ into NADH) |
| what are the reactions in electron bifurcation | 2H2 → 4 protons 2 electrons reduced NAD+ into NADH 2 electrons take ferredoxin to its reduced form Fd2- |
| What types of substrates can methanogens use to make methane? How do methanogens that use different substrates differ? | CO2 + H to directly produce methane, these methanogens compete directly with organisms practicing acetogenesis) Acetate + methyl compounds, these methanogens cooperate with acetogens since acetate is needed by these organisms |
| How does energy conservation typically occur during fermentation? | Microbes make ATP via slp, they recycle electron carriers, and the terminal electron acceptors is made by the cell *pyruvate usually |
| What is the importance of organic compounds with energy-rich phosphate bonds or acetyl-CoA molecules? | These allow for exergonic reactions, it tells us slp is happening since there is a source of energy to generate ATP |
| What is syntrophy? What is the link between the organisms in many cases? | Syntrophy = teamwork! Two microbes are working together to utilize a resource they cannot use on their own, it usually involved an exchange of hydrogen or an electron transfer |
| Why does syntrophy work? | This works by pairing reactions to create an overall negative delta G, this G value comes from a shift in the end products, making the reaction together favorable |
| What is secondary fermentation? | Using fermentation end products from another microbe for further fermentation **can be an example of syntrophy |
| What is functional diversity? What does it include? | FUNCTIONAL: form and function, the characteristics microbes have, how they interact with the environment, what functions they are performing how are they dividing |
| Why is phylogenetic diversity? | PHYLOGENETIC: evolutionary relationship between organisms, how we study diversity looking at 16s rRNA, relative similarity, taxonomy, genetic makeup |
| How do function and phylogenetic diversity correlate? | Correlate: do not always line up thanks to gene loss, convergent evolution, and HGT **can help us determine some of these events possibly happening |
| How do different nitrogen fixing organisms protect their enzymes from O2? | Exist as obligate aerobes: shut off photosystem 2 and switch to cyclic phototrophy *they get reducing power but not Oxygen |
| How do different nitrogen fixing organisms protect their enzymes from O2? part 2 | Can also: cover themselves in slime to slow oxygen diffusion into cells, separate photosythesis and nitrogen fixation by time (day vs night for cycles) |
| How do different nitrogen fixing organisms protect their enzymes from O2? Diazotrophs | stay protected by the host Free living diazotrophs can be anaerobes! They never need O2 so they live in environments without it |
| nitrogen fixing organisms protect their enzymes from O2? strategies used by Cyanobacteria | Heterocysts: terminally differentiated cells that only perform nitrogen fixation and a little bit of ATP production **cells have think cell envelopes to keep oxygen out |
| What are the problems associated with dissimilative iron-reduction? Solutions? | Fe3+ is insoluble= starting material Insoluble Fe cannot be brought into the cell, so cell adds e- to this via cytochromes in cell envelope *act as e- transfer agents |
| What are the problems associated with dissimilative iron-oxidation? Solutions? | End product is insoluble Long twisted stalks in galianella form out of cell, as iron oxidation occurs in contact w/ stalks the insoluble form sticks to stalks & bulk of cell is not touching insoluble form Leptofrix, insoluble iron sticks outside sheath |
Created by:
elliehall
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