Metabolism III Flashcards by Grace Kaufman

Where does the ETC take place?

Along the inner mitochondrial membrane

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What is REDOX potential?

Different ability to accept electrons

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What is another name for complex I?

NADH dehydrogenase

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What is another name for complex II?

Succinate dehydrogenase

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What is another name for coenzyme Q?

Ubiquinone

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What is another name for complex III?

Cytochrome C reductase

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What is another name for complex IV?

Cytochrome C oxidase

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What are the steps of electron transport through the ETC?

1) electrons from NADH–>NAD+ travel through complex I which contains FMN prosthetic groups and FeS cofactors which reduce the oxidized form of Q
2) electrons from FADH–>FAD travel through complex II which contains FeS cofactors which reduce an oxidized form of Q
3) electrons are transferred one at a time through complex III which contains heme prosthetic groups and Fe*S cofactors Q is oxidized and Cyt C is reduced
4) Cyt C is reduced by accepting a single electron at a time and bringing it to complex IV
5) electrons are transferred one at a time through complex IV which contains heme prosthetic groups, this reduces O2 which bonds with H+ from the matrix to form H2O (oxygen is the final electron acceptor)

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What happens to ubiquinone (Q) in the ETC?

It is reduced by complexes I and II and from there it travels through the membrane where it is oxidized by complex III

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What happens to H+ ions in the ETC?

They are pumped through the protein complexes from the mitochondrial matrix to the intermembrane space, creating a proton gradient

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How many H+ are pumped to the intermembrane space per cycle of the ETC?

4H+ at complex I, 0H+ at complex II, 4H+ at complex III, and 2H+ at complex IV

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What are the results of partial reduction in the ETC?

Potentially hazardous products, if one electron is transferred to O2 it forms a superoxide ion, if two are transferred peroxide is formed

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What are some pathological conditions that would yield free-radical injury?

atherogenesis, bronchitis, emphysema, Parkinson disease, Duchenne muscle dystrophy, cervical cancer, alcoholic liver disease, diabetes, acute renal failure, Down syndrome, retrolental fibroplasia, cerebrovascular disorders, ischemia, and reperfusion injury

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Define the chemiosmosis theory

ADP+Pi–>ATP is highly unfavourable so phosphorylation will not happen directly from the reaction between ADP and a high-energy P carrier, energy is needed
This energy can be provided by proton flow down an electrochemical gradient
Energy released from the ETCis used to transfer protons against the electrochemical gradient
ETC sets up a proton motive force which provides the energy to drive ATP synthesis

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What is ATP synthase and how does it function?

ATP synthase: an enzyme that synthesizes ATP

It functions by protons moving down a channel inside it which drives the production of ATP from ADP+Pi

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What re the two components of ATP synthase?

The ATPase (F1 unit) and the proton-transporting base (F0 unit) which are connected by a shaft that is held in place by a stator

What happens if the direction of the spinning rotator changes in ATP synthase?

The conformation of the F1 unit changes and ATP–>ADP+Pi instead of ADP+Pi–>ATP which dissipates the proton gradient

What is the definition of chemiosmosis?

Process fo ATP production that is dependant on a proton motive force generated by a proton electrochemical gradient

What are the net products of ETC?

For each NADH: 10 H+
For each FADH: 6 H+
Ideally 28 ATP
H2O

What are the net products of cellular respiration?

Glycolysis: 2NADH, 2ATP, 2H2O (H2O are used during P.O.)
Pyruvate Oxidation: 2NADH, 2CO2
Citric Acid Cycle: 6HADH, 2FADH2, 4CO2, 2ATP
ETC: H2O, 28ATP
Total: 32ATP, 6CO2, H2O

What is the malate-aspartate shuttle?

Occurs in the liver, kidney, and heart
NADH from the cytosol enters the inter membrane space through porins
the net effect is NADH (inter membrane) becomes NADH (matrix) with the help of malate–>oxaloacetate–>aspartate cycle and glutamate–>α-ketoglutarate cycle, this allows NADH produced in the citric acid cycle to travel into the matrix for use in the ETC

What are porins?

Openings in the outer membrane

What is the G3P shuttle?

Allows NADH synthesized in glycolysis (in the cytosol) to travel into the inter membrane space and contribute to ATP synthesis
- aided by cytosolic G3P dehydrogenase and mitochondrial G3P dehydrogenase (enzymes) to send the NADH to complex III

What is the key element of aerobic respiration?

O2 is the final electron acceptor

Which is more effective, aerobic or anaerobic respiration? Why? What does this mean for the growth of organisms with this type of respiration?

Aerobic O2 is the most effective electron acceptor because it's highly electronegative and has a large potential electron energy from NADH so it allows a large proton motive force to generate Organisms with aerobic respiration grow faster and reproduce faster

What is fermentation?

Metabolic pathways that regenerate NAD+ from NADH without oxygen as the final acceptor

What happens when there is no electron acceptor in a pathway?

The electrons have nowhere to go and the ETC will stop, NADH will build up without being regenerated to NAD+ so there will be no NAD+ to accept electrons, glycolysis/P.O./C.A.C. all stop too, this is a life threatening event

_____ can produce ATP via _____-level phosphorylation in the absence of O2 with NAD+ generated by _______.

Glycolysis/substrate/fermentation

What is lactic acid fermentation and when/where does it occur?

Glucose-->2pyruvate+2ATP+2NADH+2H-->2lactate+2NAD+ | Occurs in muscle cells when the can't get enough O2

What does lactate dehydrogenase do?

Converts lactate back to pyruvate when O2 is restored after lactic acid fermentation

What is alcohol fermentation and what does it do?

Glucose-->2pyruvate+2ATP+2NADH-->2acetylaldehyde-2CO2-->2ethanol+2NAD+ Occurs in yeast, used in production of yogurt and by prokaryotes in human intestines

What are biofuels?

Renewable fuel produced form a mixture of organic compounds produced by living organisms ex. ethanol produced from corn or sugarcane

What is the controversy surrounding biofuels?

- growing corn for fuel required more fuel expenditure - requires more water - requires more land - required more fertilizer use - less cropland is available for food - increases cost of corn for those in developing nations - may not actually reduce greenhouse gas emissions

How is corn made into ethanol?

The kernels are removed and fermented so the starch breaks down into glucose and eventually ethanol when enzymes and yeast are added, this is distilled to remove water, leaving pure ethanol which can be mixed with petroleum or used on its own as fuel

How can fats/phospholipids catabolically and anabolic ally contribute to the path of metabolism?

Catabolically: they split into glycerol and fatty acids, glycerol can enter into glycolysis and fatty acids can become acetyl-CoA Anabolically: acetyl-CoA can become fatty acids which can be used to build phospholipids and fats

How can proteins catholically and anibolically contribute to metabolism?

Catabolically: they break down into amino acids which lose their amine groups and can join the C.A.C. or become pyruvate or acetyl-CoA Anabolically: C.A.C. substrates can act as substrates for amino acid synthesis