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42 Cards in this Set
- Front
- Back
Microbes grown aerobically use glucose less rapidly than those grown anaerobically
How can this be explained ? |
The Pasteur Effect
Rate-limiting step of the EMP glycolytic pathway is the reaction catalyzed by phosphofructokinase (PFK) Fructose-6-phosphate + ATP --PFK--> Fructose-1,6-diphosphate + ADP |
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Describe an allosteric enzyme and give an example of one (used in the Embden-Meyerhoff pathway)
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An enzyme that has two binding sites:
The active site binds the substrate The allosteric site binds the effector Allosteric activators make the substrate bind better Allosteric inhibitors inhibit the binding of the substrate PFK - phosphofructokinase |
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Describe the roles of AMP, ADP and ATP in the Embden-Meyerhoff pathway
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ATP is an allosteric inhibitor
AMP and ADP are allosteric activators |
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In the presence of oxygen, the cell is undergoing:
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aerobic respiration
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In the absence of oxygen, the cell is undergoing:
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fermentation
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In the presence of oxygen, the number of ATP's per glucose molecule is:
PFK is: |
high
inhibited |
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In the absence of oxygen, the number of ATP's per glucose molecule is:
phosphofructokinase (PFK) is: |
low
not inhibited |
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Where does the tricarboxylic acid cycle occur
in eukaryotes: in prokaryotes: |
mitochondria
cytoplasm |
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For each pyruvate oxidized in the tricarboxylic acid cycle it produces:
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3 CO2 are produced by decarboxylation
4 NADH and 1 FADH2 are produced by REDOX reactions 1 Nucleoside triphosphate (NTP) is produced by substrate-level phosphorylation |
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When pyruvate is converted to Acetyl-CoA in the first step of the tricarboxylic acid cycle, this enzyme is required:
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pyruvate dehydrogenase
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A major controlling point of the TCA cycle is:
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the reaction catalyzed by citrate synthase
Oxaloacetate + Acetyl-CoA --> Citrate |
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Allosteric effectors in
Gram - bacteria: Gram + bacteria: |
NADH and α-ketoglutarate in Gram-negative bacteria
ATP in Gram-positive bacteria |
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The TCA cycle plays a biosynthetic as well as a bioenergetic role. These are examples:
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α-Ketoglutarate and oxaloacetate = Used in the biosynthesis of amino acids
Succinyl-CoA = Used for porphyrin rings for carriers which chelate iron Oxaloacetate = Can be converted to PEP, a glucose precursor Acetyl-CoA = Used in the biosynthesis of fatty acids |
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Membrane-associated electron carriers are found here in
prokaryotes: eukaryotes: |
cell membrane
inner mitochondrial membrane |
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Electron carriers and what they transport:
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Flavoproteins, Quinones = protons and e-
Iron-sulfur proteins, cytochromes = only e- |
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The accumulation of H+ on one side of the membrane, results in the generation of a:
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pH gradient
eletrochemical potential |
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Describe the proton motive force and what determines it:
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The energized state of a membrane. The accumulation of H+ on one side of the membrane causes the membrane to be energized with potential energy
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ATP synthase protein complex contains channels for:
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proton entry
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Because protons cannot permeate the membrane, these provide passage:
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ATP synthase protein complex channels
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Describe ATP synthase protein complex:
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Contains channels for protons to travel through the membrane. As protons push in through this channel, the potential energy is used to generate ATP
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How many coupling sites are there for ATP generation in the ATP synthase protein complex?
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There are 3 coupling sites for ATP generation
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List the amount of ATP generated In chemiosmotic ATP generation and where it comes from.
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Each NADH molecule produces as many as 3 ATP molecules
Each FADH₂ molecule produces as many as 2 ATP molecules |
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List the classes of chemicals that affect electron transport and give examples:
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Inhibitors = Block transport of e- through the ETC to O2
Example: Cyanide Uncouplers = Prevent the synthesis of ATP but do not interfere with electron transport Example: 2,4 dinitrophenol |
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Describe in detail (each step) the theoretical maximum ATP yield from aerobic oxidation of glucose.
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EMP Pathway of Glycolysis:
Substrate-level phosphorylation (ATP) - 2 ATP Oxidative phosphorylation with 2 NADH - 6 ATP 2 Pyruvate to 2 Acetyl-CoA: Oxidative phosphorylation with 2 NADH - 6 ATP Tricarboxylic Acid Cycle: Substrate-level phosphorylation (GTP) - 2 ATP Oxidative phosphorylation with 6 NADH - 18 ATP Oxidative phosphorylation with 2 FADH2 - 4 ATP TOTAL: 38ATP |
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Write the overall reaction for aerobic respiration of glucose.
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C6H12O6 + 6O2 + 38ADP + 38Pi --> 6CO2 + 6H2O + 38ATP
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This organism has an ETC that gives the theoretical maximum yield:
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Paracoccus denitrificans
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List the amount of ATP that Escherichia coli gives for each NADH and FADH2
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2ATP for each NADH
1ATP for each FADH₂ |
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Escherichia coli has an ETC that gives
2 ATP for every NADH 1 ATP for every FADH2 What is the maximum yield of ATP from glucose in aerobic respiration? |
EMP Pathway of Glycolysis:
Substrate-level phosphorylation (ATP) - 2 ATP Oxidative phosphorylation with 2 NADH - 4 ATP 2 Pyruvate to 2 Acetyl-CoA: Oxidative phosphorylation with 2 NADH - 4 ATP Tricarboxylic Acid Cycle: Substrate-level phosphorylation (GTP) - 2 ATP Oxidative phosphorylation with 6 NADH - 12 ATP Oxidative phosphorylation with 2 FADH2 - 2 ATP TOTAL: 26ATP |
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What is the major difference between aerobic and anaerobic respiration?
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The difference is that the TEA in the electron transport chain is a chemical compound other than oxygen. This makes the change in redox potential (E_o) much smaller and therefore less energy can be generated.
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List the anaerobic organisms given, their terminal electron acceptors, and the product formed.
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Escherichia coli NO₃- NO₂-
Escherichia coli Fumarate Succinate Desulfovibrio desulfuricans SO₄2- H₂S Methanosarcina barkeri CO₂ CH₄ Geobacter metallireducens Fe3+ Fe2+ |
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For every glucose molecule converted into pyruvate, how many NAD+ molecules are consumed during fermentation?
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2
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List the organisms and the type of fermentation:
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Escherichia: Mixed acid
Enterobacter: Butanediol Lactobacillus: Lactic acid Saccharomyces: Alcoholic Propionibacterium: Propionic acid Clostridium: Butyric acid |
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There are several different fermentation pathways but they are all similar in these ways:
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NADH is oxidized into NAD+
The electron acceptor is a pyruvate derivative |
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Describe homolactic fermentation:
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Homolactic Fermentation
Involves the EMP pathway Overall reaction: Glucose + 2 ADP + 2 Pi --> 2 lactic acid + 2 ATP |
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What organisms use homolactic fermentation?
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It is utilized by Streptococcus, some Lactobacillus
It is also utilized by algae, protozoa and even in human skeletal muscle |
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What enzyme does homolactic fermentation use?
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lactic dehydrogenase
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Describe heterolactic fermentation:
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Involves the Pentose Phosphate pathway
Overall reaction: Glucose + ADP + Pi --> lactic acid + ethanol + CO2 + ATP |
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What organisms use heterolactic fermentation?
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It is utilized by Leuconostoc, some Lactobacillus
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Describe ethanolic fermentation:
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Involves the EMP pathway
Overall reaction: Glucose + 2 ADP + 2 Pi --> 2 ethanol + 2 CO2 + 2 ATP |
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What enzyme does ethanolic fermentation use?
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Pyruvate decarboxylase
Alcohol dehydrogenase |
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What is the need of fermentation?
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For every glucose molecule converted into pyruvate, two NAD+ molecules are consumed. There is a limited amount of NAD+ in the cell so if it is not regenerated then the oxidation of glyceraldehyde-3-phosphate will cease and glycolysis will STOP
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Briefly describe the process of fermentation.
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Fermentation is an energy-yielding process in which organic molecules serve as both electron donors and acceptors
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