Term
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Definition
The Z-Ring forms a scaffold for the recruitment of other cell division proteins |
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Term
| How do we measure bacterial growth? |
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Definition
You can measure the changes in the number of cells in a population or can measure changes in mass of population
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Term
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Definition
The time required for a population to double in number.
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Term
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Definition
The assemblage of these proteins at the site of Z-Ring has been called the divisome |
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Term
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Definition
Growth rate describes how fast a bacterium grows in a particular environment |
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Term
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Definition
No increase in cell numbers, but cells may increase in mass. Unbalanced growth - cell components and proteins for nutrient uptake are synthesized |
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Term
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Definition
Cells are in balanced growth - all aspects of metabolism and growth are operating in unison. Every cell has identical generation time. Important factor in food spoilage and onset of infectious diseases. |
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Term
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Definition
Exponential growth cannot be maintained. Resources become limiting or inhibitory factors build up. Some populations sense density and stop growing. Cells continue metabolism, but most biosynthesis stops. |
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Term
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Definition
After time in stationary phase, cells begin to die. Death rate varies with species and environmental conditions |
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Term
| What is the principle behind viable count method? |
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Definition
A viability count determines the number of living cells in a sample |
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Term
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Definition
- Cell elongates and DNA is replicated
- Cell wall and plasma membrane begin to divide
- Cross-wall forms completely around divided DNA
- Cells separate
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Term
| Serial Dilutions (Plate Counts) |
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Definition
- Perform serial dilutions of a sample with sterile saline
- Inoculate Petri plates from serial dilutions
- After incubation, count colonies on plates that have 25-250 colonies (CFUs)
- Multiply number of CFUs by dilution factor
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Term
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Definition
| It is a rapid method to determine cell mass |
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Term
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Definition
A machine where a beam of light is passed through a suspension of cells; light is scattered in proportion to the number of cells present |
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Term
| How can one estimate the number of bacteria in a population? Do the various techniques provide the same information? |
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Definition
- Direct cell counts iwth a microscope counting chamber
- To determine total number of cells
- Viable cell counts with plate counts
- To determine the number of living cells
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Term
| The mathematics of growth |
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Definition
n = (logN - logN0)/0.301 N = final cell number N0 = initial cell number n = number of generations g = t/n t = hours/minutes of growth g = generation (doubling) time |
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Term
| Rate of Growth (Equation) |
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Definition
k = 2.303 (logN - logN0)/t k = mean growth rate constant |
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Term
Bacterial population increases from 103 to 109 cells in 10 hours. |
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Definition
N0 = 103 N = 109 t = 6 Hours n =(log109 - log103)/0.301 = 6/0.301 = 19.9 = 20 Generations g = t/n = 10/20 = 1/2
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Term
| Bacterial population increases from 103 to 108 in 6 hours. What is k? |
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Definition
N0 = 103 N = 108 t = 6 Hours k = 2.303*(log108 - log 103)/6 k = 2.303*(8-3)/6 k = 1.92 |
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Term
| How can one measure the rate of growth of a bacterial culture? |
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Definition
By measuring over time any growth relevant parameter - Cell mass
- Viable cell number
- Total cell number
- Dry weight
- Any chemical cell constituent (DNA, RNA, Protein)
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Term
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Definition
A small population of bacteria added to a growth medium
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Term
Why might a culture have a long lag phase after inoculation? |
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Definition
It might have a long lag phase because it needs to change to accomidate to the new medium (i.e. synthesize cell materials) |
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Term
| Possible reasons for entry into stationary phase |
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Definition
- Nutrient limitation
- Limited oxygen availability
- toxic waste accumulation
- critical population density reached
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Term
| List two physiological changes that are observed in stationary phase cells. How do these changes impact the organism's ability to survive? |
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Definition
- Morphological changes (e.g. endospore formation)
- Decrease in size
- Nucleoid condensation
- Production of starvation proteins
- Protect DNA
- Prevent protein denaturation
- Prevent oxidative damage
- Long-term suvival
- Increased Virulence
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Term
| Why can't one always tell when a culture enters the death phase by the use of total cell count? |
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Definition
This is because you cannot tell the difference between live and dead cells |
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Term
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Definition
Nutrients are added in excess of amount needed to attain maximum growth rate. Results in a balanced state of growth for a few generations
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Term
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Definition
Minimum needed to stay alive and perform basic functions
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Term
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Definition
Used to keep bacterial cultures in exponential phase
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Term
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Definition
Nutrients are continuously added and waste products removed |
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Term
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Definition
Nutrients are consumed and end products accumulate
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Term
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Definition
Must have O2 as the terminal electron acceptor
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Term
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Definition
Use Oxygen when available, but can utilize anaerobic pathways as well
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Term
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Definition
Occupy niches with limited oxygen level--2 to 10% O2 |
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Term
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Definition
Are killed by even small amounts of O2
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Term
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Definition
Live in moderately salty habitats such as seawater (0.4M NaCl). Many are obligate halophiles |
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Term
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Definition
Grow at higher salt concentrations, approaching saturation
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Term
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Definition
Cannot tolerate moderate salt concentrations
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Term
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Definition
Species can live in a range of conditions from no salt to moderate levels |
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Term
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Definition
Growth below 20 degress celsius
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Term
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Definition
Growth at 20 to 44 degrees celsius |
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Term
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Definition
Growth at 44 to 70 degrees celsius
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Term
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Definition
Growth above 70 degrees celsius |
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Term
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Definition
Microbes that grow at low pH (below pH 3)
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Term
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Definition
pH 5-8. Most human pathogens
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Term
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Definition
Grow at high pH (above pH 9) |
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Term
| How have aerobes adapted to tolerate the presence of toxic oxygen products? |
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Definition
By removing the damaging effects with protective enzymes |
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Term
| Why is water activity important for microbial growth? What changes water activity? |
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Definition
Water activity is important because it designates the amount of water, which is important for growth because certain organisms need certain amounts of water. Water activity can be changed by the amount of solutes and surfaces around. |
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Term
| What is an osmoprotectant and why is it needed? |
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Definition
They are compatible solutes used to increase a cell's internal osmotic concentration and prevent further shrinking or swelling of the cell |
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Term
| How do acidophiles and alkaliphiles manage to grow at the extremes of pH? |
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Definition
They use: - Proton/Ion exchange mechanisms
- K+/H+ antiporter to remove internal protons
- Na+/H+ antiporter to bring protons into the cell
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Term
| What are the ranges of temperature, pH, and osmotic pressure that are compatible wih the growth of bacteria and archaea? |
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Definition
They are compatible in a wide range of all three categories |
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Term
| How does activity of superoxide dismutase differ from that of superoxide reductase? |
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Definition
Superoxide reductase involves cytochrome c being oxidized, while superoxide dismutase does not. Also, superoxide dismutase has O2 as a byproduct. |
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Term
| If anaerobes cannot live in oxygen, how do they incorporate oxygen into their cellular components? |
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Definition
They use oxygen in a different form, such as water or carbon dioxide. The only form that is toxic is oxygen gas. |
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Term
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Definition
The vapor pressure of air over a substance divided by the vapor pressure over pure water or the water that is available to the cell |
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Term
| When a cell is in an environment of low water activity, what happens to cellular water? |
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Definition
If solute concentration is higher in the medium than in the cell, water leaves the cell and the cell membrane collapses inward--plasmolysis
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Term
| Adaption methods to life at high temperatures |
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Definition
- Protein structure stabilized by a variety of means
- More H bonds
- more proline
- chaperones
- Histone-like proteins stabilize DNA
- Membrane stabilized by variety of means
- more saturated, more branched, and higher molecular weight lipids
- ether linkages (archaeal membranes)
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Term
| What donates electrons to the electron transport system (ETS)? |
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Definition
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Term
| What accepts electrons from the electron transport system (ETS)? |
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Definition
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Term
| Where is the PMF generated? |
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Definition
| Across the cytoplasmic membrane |
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Term
| What is the role of ATP synthase? |
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Definition
| Used to drive synthesis of ATP |
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Term
| Why is respiration associated with the cell membrane? |
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Definition
The membrane is needed to generate the PMF and the respiratory proteins are located there |
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Term
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Definition
| A hydrophobic non-protein electron carrier |
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Term
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Definition
They are proteins containing an iron-porphyrin ring called heme. Several classes, differ in reduction potential |
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Term
| What does the cell need to grow? |
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Definition
Appropriate nutrients: - Source of energy to fuel cell growth
- Carbon for cell biosynthesis
- Other nutrients, N,S, P, etc.
Appropriate environmental conditions: - pH, oxygen, temperature, etc.
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Term
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Definition
The breakdown of larger, more complex molecules into smaller, simpler ones, during which energy is released, trapped, and made available to work
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Term
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Definition
The synthesis of complex molecules from simpler ones during which energy is added as input
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Term
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Definition
- Substrate-level phosphorylation
- Electron transportphosphorylation (aKa respiration-linked phosphorylation)
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Term
| Substrate-Level phosphorylation |
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Definition
Transfer of Pi from a high energy phosphorylated intermediate to ADP by a kinase enzyme. Phosphorylated intermediates are generated during: glycolysis, TCA cycle, and fermentation. |
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Term
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Definition
- Start
- Energy Input
- Cleave
- Reductions
- Substrate level phosphorylation
- Dehydration
- Substrate level phosphorylation
- End products
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Term
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Definition
Intermediates change from one form to another - Converts pyruvate to:
- CO2
- Reducing power
- NADH
- FADH2
- Used in electron transport for additional ATP synthesis
- ATP
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Term
| Electron Transport Phosphorylation |
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Definition
Required Components: - Cytoplasmic membrane
- electron transport chain => redox reaction
- Proton + charge gradient => pmf
- Membrane-bound ATP synthase => ATP
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Term
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Definition
Tendency to donate or accept electrons given in Volts. Standard conditions: pH 7.0, 1M, 25 degrees celsius
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Term
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Definition
The amount of energy in a system that is available to do work. A negative delta G indicates that the reaction is favorable and will proceed spontaneously. A positive delta G indicates that the reaction is unfavorable and will only proceed if energy is supplied |
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Term
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Definition
- A NADH dehydrogenase to oxidize the e-donor NADH
- NADH - Diffusible electron carrier
- Flavoproteins, proteins bound to flavins (FMN, FAD)
- Iron sulfur proteins
- Quinones - hydrophobic non-protein electron carriers
- Cytochromes - proteins containing an iron-porphyrin ring called heme
- Terminal oxidase (reductase) to reduce the e-acceptor oxygen to water
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Term
NADH + H+ --> NAD+ E0' = -0.32 V 1/2 O2 --> H2O E0' = +0.818 V How much energy is released? |
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Definition
Delta E0' = 0.8181-(-0.32) = 1.138 V Delta G0' = -n x F x Delta E0' (kJ/mol) Delta G0' = -2 x 96.5 kJ/Vmol x 1.138 V Delta G0' = -219.6kJ/mol
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Term
| How much energy does it take to make 1 ATP? |
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Definition
Delta G0' = +80 kJ/mol to form 1 mol ATP (True) 3 mol ATP/mol NADH were determined experimentally
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Term
| Inhibitors of ATP Synthesis |
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Definition
- Blockers (inhibitors) that inhibit the flow of electrons through the system
- Carbon monoxide, cyanide bind to cyt
- Uncouplers that allow electron flow, but disconnect it from oxidative phosphorlation
- Dinitrophenol, lipid soluble make membrane leaky and destroy the PMF and ATP production by oxidative phosphorylation
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Term
| Law of Conservation of Energy |
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Definition
States that in an isolated system the total energy remains constant
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Term
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Definition
- An ATP generating metabolic process in which the organic degradation products act as electron donors and acceptors
- Small amount of energy is obtained via substrate level phosphorylation
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Term
| Glycolysis and Fermentation |
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Definition
- Glycolysis is an example of fermentation
- A major pathway for anabolic reactions
- A major pathway for energy conservation
- Two ATPs, two NADHs, and pyruvate are produced
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Term
| Organisms that perform lactic acid fermentation |
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Definition
- Several genera
- Gram +
- Aerotolerant anaerobes
- Many are auxotrophs
- Live in organic rich environments
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Term
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Definition
Glucose --> 2 lactic acid Uses glycolytic pathway 2 moles of ATP made per 1 mole glucose MORE ATP than hetero
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Term
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Definition
Glucose --> lactic acid + ethanol + CO2 Lacks the aldolase enzyme and cannot use the glycolytic pathway 1 mole of ATP per mole of glucose LESS ATP than homo
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Term
| What happens to the lactate? |
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Definition
Transported out by lactate symporter. Takes a proton out with it Lactate is still a good energy source
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Term
| Other fermentable carbohydrates |
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Definition
- Monosaccharides
- Fructose, mannose, galactose get converted to glucose-6-phosphate or fructose-6-phosphate
- Disaccharides--get cleaved into monosaccharides by specific enzymes
- Lactose => galactose and glucose
- Maltose => 2 glucoses
- Sucrose => glucose and fructose
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Term
| Lactic acid bacteria are wasteful? Or are they? |
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Definition
- They live in organic rich environments without oxygen
- The lactate:proton symporter can generate a proton motive force, however, this is dependent on the pH of the environment
- They make acid which inhibits competitors
- They can grow in low iron environments
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Term
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Definition
- Anaerobic, Gram + bacteria
- The form spores
- Lack a respiratory chain
- They ferment a variety of substrates
- Many secrete butyric acid, acetic/lactic acids, ethanol, H2, and CO2
- Many are proteolytic: break down proteins and ferment them
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Term
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Definition
- Ubiquitous in soil, aquatic sediments, and muds
- Spore forming is an ideal survival strategy for soil bacteria
- Heat shocking can activate growth of the spore
- Some are pathogenic and cause gangrene
- Some produce deadly toxins
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Term
| Examples of fermentations carried out by Clostrida |
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Definition
Butyric acid fermentation and amino acid fermentation
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Term
| How can microbes conserve more energy from glucose? |
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Definition
Cells do this by coupling glucose oxidation to the reduction of a terminal electron acceptor like oxygen
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Term
| Why did the muddy chicken cross the road twice? |
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Definition
| He was a dirty double crosser |
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