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DesLee26
on FreezingBlue Flashcards.
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Why is cyanide a poison?
it binds irreversibly to cyt ala3, a protein in the ETC, thus inhibiting aerobic respiration from yielding the ATP the body requires to function properly
it blocks oxygen from binding to the ETC--> tissue hypoxia
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CoA is a __, containing an __ group. When acetyl-CoA forms, it does so via __.
- thiol
- --SH
- covalent attachment of the acetyl group to the --SH group
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Pyruvate dehydrogenase
pyruvate is oxidized, yielding CO2, while the remaining two-carbon molecule binds covalently to TPP
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Dihydrolipoyl transacetylase
two-carbon molecule bonded to TPP is oxidized and transferred to lipoic acid, whose disulfide group acts as an oxidizing agent, creating the acetyl group.
It then catalyzes the CoA-SH interaction with the newly formed thioester link, causing transfer of an acetyl group to form acetyl-CoA; lipoic acid is left in its reduced form
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Dihidrolipoyl dehydrogenase
FAD is used as a coenzyme in order to reoxidize lipoic acid, allowing lipoid acid to facilitate acetyl-CoA formation in future reactions.
- As lipoid acid is reoxidized, FAD is reduced to FADH2
- In subsequent reactions, FADH2 is reoxidized to FAD, while NAD+ is reduced to NADH
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What other pathways are capable of producing fatty acids?
beta (fatty acd) oxidation
amino acid catabolism
ketones
alcohol
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beta oxidation
because fatty acyl-CoA cannot cross the inner mitochondrial membrane, the fatty acyl group is transferred to carnitine via a transesterification reaction
once acyl-CoA is in the matrix, beta oxidation occurs
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function of carnitine
cary the acyl group from a cytosolic CoA-SH to a mitochondrial CoA-SH
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amino acid catabolism
some amino acids form acetyl-CoA by losign their amino group via transamintation; their carbon skeletons form ketone bodies
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ketones
ketones can poduce acetyl CoA
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alcohol
alcohol dehydrogenase or acetaldehyde dehydrogenase
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In regards to the CAC, what happens if oxygen is absent?
NADH and FADH2 will accumulate if oxygen is not available.
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What is isoctrate
an isomer
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What converts citrate to isocitrate?
aconitase
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What is the rate limiting step in the CAC?
isocitratedehydrogenase
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synthetases
reate new covalent bonds with energy input
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nucleosidediphosphate
transfers a phosphate from GTP to ADP
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Only step of the CAC that doesn't occur in the matrix is...
fumaate formation by succinate dehyrogenase, which occurs in the inner mitochondrial membrane
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net results and atp yield of the CAC
Per cycle:
- 4 NADH--> 10 ATP
- 1 FADH2--> 1.5 ATP
- 1 GTP--> 1 ATP
Total: 12.5 ATP per pyruvate= 25 ATP
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Yield for glycolysis
two ATP and two NADH
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What inhibits acetyl CoA production?
phsophorylating PDH
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What activates PDH?
pyruvate dehydrogenase phosphatase in response to high levels of ADP
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control points of the CAC
1) citrate synthase
2) isocitrate dehydrogenase
3) alpha-ketoglutarate dehydrogenase complex
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control of citrate synthase
ATP and NADH function as allosteric inhibiton of citrate
ADP and NAD+ fuction as allosteric activators
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control of alpha-ketoglutarate dehydrogenase complex
succinyl-CoA and NADH are inhibitors; ATP is as well
stimulated bby calcium and ADP
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During a metabolically active state, __ and __ should rise and __ and __ decline.
ADP and NAD+
ATP and NADH
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The formation of ATP is __ and electron transport is __.
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How many protons are pumped into the intermembrane space by...
Complex I
1) four
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How many protons are pumped into the intermembrane space by...
Complex II
zero
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Why are cytochrome c molecules needed?
becase coenzyme Q only transfers one electron at a time via the Q cycle
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Explain the Q cycle.
two electrons are shuttled from ubiquinol near the intermembrane space to a molecule of ubiquinone near the mitochondrial matrix. Another two electrons are attached to heme moieties, reducing two molecules to cyt c. A carrier assists.
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How many protons are pumped into the intermembrane space by...
Complex III
four protons
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How many protons are pumped into the intermembrane space by...
Complex IV
two
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ATP synthase parts
F0: functions as an ion channel, so protons travel through F0 along their gradient back into the matrix
F1: utilizes the energy released from the electrochemical gradient to phosphorylate ADP to ATP
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What does the theory of conformational coupling suggest?
that the relationship between the proton gradient and ATP synthesis is indirect. Instead, ATP is released by the synthase as a result of conformational change caused by the gradient
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What happens if O2 is limited?
the rate of oxidative phosphorylation decreases, and the concentrations of NADH and FADH2 increase. The accumulation of NADH inhibits the CAC
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In the presence of adequate O2, the rate of oxidative phosphorylation is dependent on __. The concentrations of ADP and ATP are __.
the availability of ADP
reciprocally related
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