Chapter 3: Microbial Metabolism Flashcards
A microbe has a metabolic pathway in which NAD+ donates an electron to an electron transport chain and then the electron is transported to sulfur, producing H2S gas. This must be ___________
anaerobic respiration
In _________, the electron acceptor is an organic molecule such as pyruvate.
fermentation
In ___________, the terminal electron acceptor is oxygen.
aerobic respiration
When an electron is added to a chemical, then the chemical has been _______ (and not oxidized).
reduced.
If you traced the movement of an electron in purple bacteria, what would you find?
The electron would be reused repeatedly in photophosphorylation.
The electron is reused repeatedly in photophosphorylation- _________
(purple bacteria)
The electron begins at _____ and returns to ________.
cyclic photophosphorylation
-P870
-P870
P680 is the electron center in Photosystem II of ____________ in organisms with chlorophyll a (plants, green algae, and cyanobacteria). It is not found in purple bacteria
noncyclic photophosphorylation
What types of energy conservation are possible in photosynthetic algae?
substrate-level phosphorylation, oxidative phosphorylation, and photophosphorylation.
Only photosynthetic organisms use photophosphorylation, in which light energy is used to produce adenosine triphosphate (ATP)
A common carbon source for chemolithotrophs is __________
carbon dioxide
Glucose and amino acids are carbon sources for _____________
chemoorganotrophs
What can be concluded about anoxygenic phototrophs?
it could belong to several groups of bacteria– these are prototrophs that do not produce oxygen.
_________ eukaryotes produce oxygen
phototrophic
Which are the products of the aerobic breakdown of a single molecule of glucose?
6 CO2 + 6 H2O
Why is it helpful for some cyanobacteria to have nitrogenase in a heterocyst?
The heterocyst provides an anoxic environment.
Nitrogenase requires a very low oxygen environment to function, well below atmospheric concentrations. Needs anoxic env. to function, but not for assembly.
N2 is obtained from the air and does not need to be actively pumped into heterocysts.
_________ pump protons to maintain an acidic internal environment.
Lysosomes
RuBisCO can react with carbon dioxide and with oxygen, so what do you predict would happen to a photosynthetic bacterial cell that relied on the Calvin cycle in an atmosphere with a very high oxygen concentration?
The cell would produce less glyceraldehyde-3-phosphate.
Does an enzyme affect whether a reaction is exergonic or endergonic?
No, because enzymes lower the activation energy but do not affect the free energy change.
What would happen if a cell using glycolysis lost the ability to regenerate NAD+?
The cell would die because glycolysis would cease once there was no remaining NAD+
When NAD+ is reduced,_____ is formed. NADH then must be oxidized to form NAD+ to allow glycolysis and other reactions to continue.
NADH
During ________, NADH donates an electron to an organic molecule (such as pyruvate) to regenerate NAD+ as NAD+ is needed for fermentation to continue.
fermentation
What can you predict about a bacterial cell that is growing in the Antarctic?
It has a relatively high percentage of short chain and unsaturated fatty acids.
These adaptations help to maintain membrane fluidity at cold temperatures.
Which domains include species capable of nitrogen fixation?
Bacteria and Archaea
There are no eukaryotic cells capable of nitrogen fixation.
