MICRO 101 Chapter 11
Terms in this set (88)
Electron Source of Lithotrophs?
Reduced inorganic molecules
Carbon Source of Heterotrophs?
Reduced, preformed, organic molecules from other organisms
Carbor Source of Autotrophs?
CO2 sole or principal biosynthetic carbon source
Energy Sources of Phototrophs?
Energy Source of Chemotrophs?
Oxidation of organic or inorganic compounds
Electron Source of Organotrophs?
What are representative microorganisms of Photolithoautotrophs?
Purple and green sulfur bacteria, cyanobacteria, diatoms
What are representative microorganisms of Photoorganoheterotrophs?
Purple nonsulfur bacteria, green nonsulfur bacteria
What are representative microorganisms of chemolithoautotrophs?
Sulfur-oxidizing bacteria, hydrogen-oxidizing bacteria, methanogens, nitrifying bacteria, iron-oxidizing bacteria
What are representative microorganisms of Chemolithoheterotrophs?
Some sulfur-oxidizing bacteria
(e.g., Beggiatoa spp.)
What are representative microorganisms of Chemoorganoheterotrophs?
Most nonphotosynthetic microbes, including most pathogens, fungi, and many protists and archaea
From within the cell
Fermentation uses an electron acceptor that is endogenous (from within the cell) and does NOT involve an electron transport chain.
True or False?
As electrons pass through the chain to the final electron acceptor, a type of potential energy called the _______A_________ is generated and used to synthesize ___B___ from ___C___ and phosphate (Pi)
A. proton motive force (PMF)
In Fermentation, the endogenous electron acceptor is usually an intermediate (e.g., pyruvate) of the catabolic pathway used to __________________________.
Degrade and oxidize the organic energy source.
During fermentation, ___A____ is synthesized almost exclusively by substrate-level phosphorylation, a process in which a phosphate is transferred to ___B___ from a ___ C (High or Low Energy)____ molecule (e.g., phosphoenolpyruvate) generated by catabolism of the energy source.
__________ molecules serve as energy and electron sources for all three fueling processes used by chemoorganotrophs
The catabolic pathways of greatest importance to chemoorganotrophs are the ___A____ and _____B______ .
They are important not only for their role in catabolism but also for their roles in ___C____.
They supply material needed for biosynthesis, including _____D_____ and _____E_____.
A. glycolytic pathways
B. the tricarboxylic acid (TCA) cycle
D. precursor metabolites
E. reducing power
With the exception of CO2-fixation, fueling reactions are all ______________.
Virtually all pathogenic bacteria are of what nutritional type?
Aerobic respiration is ___________
a process that can completely catabolize a reduced organic energy source to CO2 using the glycolytic pathways and TCA cycle with O2 as the terminal electron acceptor for an electron transport chain
Aerobic respiration can be divided into how many steps?
What are the steps that make up Aerobic respiration?
1. It begins with the formation of pyruvate, using one or more pathways. These pathways also produce NADH, FADH2, or both.
2. Next pyruvate is fed into the TCA cycle and oxidized completely to CO2 with the production of some GTP or ATP, NADH, and FADH2 .
3. Finally, the NADH and FADH2 formed by glycolysis and the TCA cycle are oxidized by an electron transport chain, using O2 as the terminal electron acceptor.
It is the activity of the _________ that conserves most of the energy used to make ATP during aerobic respiration.
electron transport chain
What is the most common pathway for glucose degradation to pyruvate?
The Embden-Meyerhof pathway
The Embden-Meyerhof pathway is divided into how many parts? What are they?
The Embden-Meyerhof pathway
is divided into two parts: a 6 carbon phase and a 3-carbon phase.
In the initial 6-carbon phase of the Embden-Meyer pathway, ATP is used to phosphorylate glucose how many times?
What is the product?
Embden-Meyerhof Pathway can function during aerobic respiration, anaerobic respiration, and fermentation.
True or False?
Regarding Embden-Meyerhof Pathway:
When used during respiration, the electrons accepted by ___A___ are transferred to an electron transport chain and are ultimately accepted by an ___B____ electron acceptor.
Regarding Embden-Meyerhof Pathway:
When used during fermentation, the electrons accepted by NAD+ are donated to an ___________ electron acceptor (e.g., pyruvate).
NADH and ATP are produced in the 3-carbon phase of the Embden-Meyerhof pathway.
True or False
what are the products in the 3-carbon phase of the Embden-Meyerhof pathway?
NADH and ATP
ATP is produced in the 6-carbon phase of the Embden-Meyerhof pathway.
True or False?
ADP is produced
True of False
In substrate-level phosphorylation, ADP phosphorylation is coupled with the exergonic hydrolysis of a high-energy molecule having a higher phosphate transfer potential than ATP
True or False?
The Entner-Doudoroff pathway is used by mostly Gram-positive bacteria.
The Entner-Doudoroff pathway is used by some Gram-negative bacteria
(Very rarely by Gram-positive)
Is the The Entner-Doudoroff pathway used by EukaryoteS?
Does the Entner-Doudoroff pathway essentially replace the first or second phase of the Embden-Meyerhof pathway?
The Entner-Doudoroff pathway essentially replaces the first phase of the Embden-Meyerhof pathway
the pyruvate dehydrogenase complex oxidizes and cleaves pyruvate to form ____________
one CO2 and the 2-carbon molecule acetyl-coenzyme A (acetyl-CoA)
Oxidative phosphorylationv is best explained by the _____________ hypothesis
According to the chemiosmotic hypothesis, mitochondrial ETCs are organized so that protons move across the _____________ from the mitochondrial matrix to the intermembrane space as electrons are transported down the chain.
In bacteria and archaea, the protons usually are moved across the plasma membrane from the ____A____ to the ____B_____.
B. periplasmic space
coenzyme Q, a lipid-soluble molecule that moves freely in the membrane, accepts ________A__________but delivers only __________B___________ to complex _____ of the mitochondrial chain
A. two electrons and two protons
B. two electrons
the Q cycle ultimately moves _____________ across the membrane
The Q cycle involves the sequential oxidation of two reduced coenzyme Q molecules (QH2).
How are the four electrons transferred?
The transfer of two of the four electrons released by these oxidations to one molecule of the oxidized form of coenzyme Q (located nearby in the membrane) via the cytochrome b located in complex III, and the transfer of the remaining two electrons to the FeS protein of complex III.
True or False?
As long as the membrane is intact, the mitochondrial matrix is more ALKALINE and more NEGATIVE than the intermembrane space.
True or False?
As long as the membrane is intact in bacterial and archaeal cells, the cytoplasm is more alkaline and more negative than the periplasmic space.
Combined chemical and electrical potential differences make up the proton motive force (PMF). The PMF is used to perform work when protons flow. This flow is ______A______and is often used to phosphorylate _
B. ADP to ATP.
PMF is also used by many secondary active transport systems, such as _____________________________
- to move nutrients into the cell
- to rotate the bacterial flagellar motor.
The mitochondrial F1 component appears as a spherical structure attached to _______________
the mitochondrial inner membrane surface by a stalk
The F0 component is ___________________________
embedded in the membrane
ATP synthase is on the ________ of the plasma membrane in bacterial cells.
F0 participates in ___________________
proton movement across the membrane.
F1 is a large complex in which ________A________ subunits alternate with _____B______ subunits.
A. three α
B. three β
The catalytic sites for ATP synthesis are located on the __________.
At the center of F1 is the __________ subunit.
The γ subunit extends through ___A____ and interacts with ______B______.
ATP synthase functions like a ____A____ engine.
It is thought that the flow of protons down the proton gradient through the ____B_____ subunit causes ______C_____and the _____D____ subunit to rotate.
During ATP Sythase, as the ____A____ sub-unit rotates rapidly within the _____B______ (much like a car's crankshaft), conformation changes occur in the ____C______ subunits
Oxidative phosphorylation accounts for ________ times more ATP than does substrate-level phosphorylation
What is the maximum total yield of ATP during aerobic respiration by eukaryotes?
One NADH yields how many ATP?
1 NADH = 2.5 ATP
One FADH2 yields how many ATP?
1 FADH2 = 1.5 ATP
Do bacterial ETCs have lower P/O ratios than eukaryotic chains? Are their ATP yields are smaller or larger?
Yes, bacterial ETCs have lower P/O ratios than eukaryotes.
Their ATP yields are smaller.
Why do bacterial ETCs have lower P/O ratios than eukaryotic chains?
Bacterial ETCs are often shorter and therefore transport fewer protons across the plasma membrane.
What is the concept of the phosphorus to oxygen (P/O) ratio?
a measure of the number of ATP molecules (phosphorus) generated per oxygen (O) reduced as NADH and FADH2 were oxidized.
What is Anaerobic respiration?
Anaerobic respiration is the chemoorganotrophic process whereby an exogenous terminal electron acceptor other than O2 is used for electron transport.
Who is anaerobic respiration used by?
It is carried out by many bacteria and archaea, and some eukaryotic microbes.
what are the most common terminal electron acceptors used during anaerobic respiration?
Nitrate, sulfate, and CO2
(metals and a few organic molecules can also be reduced)
The ____________ reduction of NO3¯ makes it unavailable for assimilation into the cell.
What is the name of this process?
- The use of a substance as an electron acceptor for an electron transport chain. The acceptor (e.g., sulfate or nitrate) is reduced but not incorporated into organic matter.
The anaerobic reduction of NO3¯ makes it unavailable for assimilation into the cell.
That is, it can't be used to construct N-containing molecules such as amino acids and nucleotides.
dissimilatory nitrate reduction
Does anaerobic respiration produce as much ATP as aerobic respiration?
NO, Anaerobic respiration does not produce as much ATP as aerobic respiration.
Why doesnt anaerobic respiration produce as much ATP as aerobic respiration?
The lower ATP yield is due to the fact that alternate electron acceptors such as NO3¯ have less positive reduction potentials than O2.
If the difference in standard reduction potentials is small, than less energy is available to make ATP in anaerobic respiration because energy yield is directly related to the magnitude of the reduction potential difference.
Why is anaerobic respiration useful?
anaerobic respiration is useful because it allows ATP synthesis by electron transport and oxidative phosphorylation in the absence of O2.
Does fermentation involve an electron transport chain?
What are the four unifying themes that should be kept in mind when microbial fermentations are examined?
(1) NADH is oxidized to NAD+
(2) O2 is not needed
(3) the electron acceptor is often either pyruvate or a pyruvate derivative
(4) an ETC is not used to reoxidize NADH, and this reduces the ATP yield per glucose significantly
What is the most common fermentation?
lactic acid (lactate) fermentation, the reduction of pyruvate to lactate
Where does lactate fermentation occur?
It occurs in bacteria (lactic acid bacteria, Bacillus spp.), protists (Chlorella spp. and some water molds), and animal skeletal muscle.
Lactic acid fermenters can be separated into two groups:
Homolactic fermenters and Heterolactic fermenters
Homolactic fermenters use the ______A_____ pathway and directly reduce almost all their pyruvate to lactate with the enzyme _______B______.
B. lactate dehydrogenase
Heterolactic fermenters use the ____A_____ pathway to form substantial amounts of products other than lactate.
- many also produce ethanol and CO2
A. pentose phosphate
Another common fermentation is carried out by many fungi, protists, and some bacteria, which is called ___________________________
Microbes ferment sugars to ethanol and CO2 in a process called __________________
In alcoholic fermentation, _______A_________ is decarboxylated to ________B_________, which is then reduced to ethanol by alcohol dehydrogenase with _______C_______ as the electron donor
Mixed acid fermentation results in the excretion of ________A________ and a mixture of acids, particularly ____________B (more than 1)_____________
B. acetic, lactic, succinic, and formic acids
Members of what genera carry out mixed acid fermentation?
Members of the genera Escherichia, Salmonella, and Proteus carry out mixed acid fermentation.
Butanediol fermentation is characteristic of members of the genera _________________.
Enterobacter, Serratia, Erwinia, and some species of Bacillus
he predominant pathway used during Butanediol fermentation yields _______A_______.
However, large amounts of __________B__________ also are produced, as are smaller amounts of lactic acid and formic acid
*In some bacteria, the formic acid is further catabolized to ________D_______ .
C. lactic acid
D. H2 and CO2
The use of either mixed acid fermentation or butanediol fermentation is important in differentiating members of the family ___________________________