Chapter 7B - Microbial Metabolism: Fermentation & Respiration Flashcards
What type of energy is used to accomplish work in the cell?
Chemiosmotic potential
The chemiosmotic potential that releases energy during ionic movement
Many active-transport reactions and the rotation of the prokaryotic flagellum are drivement by the movement of ________ down a concentraiton gradient.
Ions
The chemiosmotic potential that releases energy during ionic movement is due to the ________________ of the cell being more acidic and more positively charged relative to the ____________ of the cell.
Exterior
Interior
What are two ways in which a chemiosmotic potential can be made?
- Electron transport systems (respiratory or phototrophic cells)
- ATP synthase
A chemiosomotic potential can be made in two ways: electron transport chain or ____________, both of which pump ions across a membrane. However, ___________ can work in opposite direction, too.
ATP synthases/ATPases
The ______________ of the cell tends to be more positively charged and the _____________ of the cell tends to be less positively charged.
Surface
Inside
_____________________ is the movement of ions across a semipermeable membrane down their electrochemical gradients.
Chemiosomosis
_____________________ refers to catabolic reactions producing ATP in which organic or inorganic compounds are primary electron donors and organic or inorganic compounds are ultimate electron acceptors; oxidation of a compound occurs with a terminal electron acceptor that is usually accompanied with ATP synthesis via oxidative phosphorylation.
Respiration
________________________ refers to catabolic reactions producing ATP in which organic compounds serve as primary electron donor and electron acceptor; ATP is produced by substrate-level phosphorylation; and there is no need for external electron acceptors.
Fermentation
Is glycolysis a type of fermentation or respiration?
Fermentation
The simplest and probably the oldest form of energy metabolism is _____________________ in which ATP is generated by substrate-level phosphorylation and ATP synthase functions in the direction of ATP hydrolysis to generate a protonic potential.
Fermentation
What is the basic strategy of fermentation?
The transfer of inorganic phosphate to a high-energy organic compound that can then be used to create ATP via substrate-level phosphorylation
In order for substrate-level phosphorylation to occur via fermentation, the phosphate has to be added to the organic compound as a “low-energy” phosphate, like in __________________________, and then converted to a “high-energy,” like in phosphoenolpyruvate (PEP).
2-phosphoglycerate
Fermentation produces end products at the same average _____________ level as the substrates.
Redox
Do all fermentations require redox reactions?
No; there are a few that do not in which the chemistry is such that a substrate-level phosphorylation can occur without any oxidation of the organic substrate
Three different strategies are used to incorporate oxidation reactions into fermentation pathways. What are they?
- Part of the substrate molecule is oxidized and part of it is reduced
- The substrate is first oxidized and then the oxidized intermediate is reduced
- Two different substrates are used, one being oxidized and the other being reduced
What is the goal of homolactic fermentation?
To regenerate NAD+
In _______________________ fermentation, glucose is oxidized to pyruvate, producing ATP and NADH, and the NADH is reoxidized by reducing pyruvate to _____________.
Homolactic
Lactate
What is the goal of ethanol-acetate fermentation?
To produce ATP
In _____________________ fermentation, one branch produces ATP while the other reoxidizes NADH.
Ethanol-acetate
What is the goal of Strickland fermentation?
To produce ATP
In ____________________ fermentation, one amino acid (alanine in this case) is oxidized to produce ATP while another amino acid (glycine in this case) is reduced to reoxidize NADH).
Strickland
A common fermentation of the amino acid ___________________ involves non-oxidative or reductive rearrangements and cleavage to produce ornithine and the high-energy compound carbamoyl phosphate, which can transfer its phosphate to ADP.
Arginine
What is fumarate respiration?
A fermentation process in which fumarate reductase cataylzes the reduction of fumarate to succinate and pumps two H+ per fumarate reduced into the periplasm
________________ ______________________ pumps protons as it conveys electrons to fumarate, contributing to the protonic potential without expending ATP to do so.
Fumarate reductase
Why is respiration more efficient than fermentation?
Because it couples the oxidation of organic compounds to the reduction of a separate electron acceptor, usually oxygen. The presence of an electron acceptor separate from the organic substrate allows the latter to be oxidized completely, thus liberating more energy than if significant amounts of it have to be excreted by waste; furthermore, respiration involves an additional and highly effective mechanism of energy conservation: chemiosmotic energy conservation
______________________ is a type of chemotrophic energy metabolism in which most or all of the ATP is made by chemiosmotic means.
Respiration