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29 Cards in this Set
- Front
- Back
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Describe the electron transport in general
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a series of protein complexes embedded in the inner mitochondrial membrane
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What is the overall purpose of the ETC
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to transfer electrons from NADH or FADH2 to the final electron acceptor, molecular oxygen
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What happens to the energy released during the ETC
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the energy is harnessed to drive the synthesis of ATP via oxidative phosphorylation
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Where is the ETC located?
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the inner mitochondrial membrane
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What are the 5 types of redox carriers found in the ETC
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1. heme groups
2. iron-sulfur clusters 3. flavins 4. coenzyme Q 5. copper ions |
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describe the pattern of redox in the ETC
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each sucessive eletron carrier is alternativley reduced then oxidized
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What determines the direction of electron transport in the ETC
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the direction of transport is determined by the affinity of the redox carrier for electrons. Electrons flow from good donors with low electron affinity to good acceptors with higher affinity for electrons
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How many electrons can cytochromes carry
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1
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how many electrons can iron sulfur proteins carry
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1
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how many electrons can flavins carry
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2 electrons + 2H+
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how many electrons can coenzyme Q carry
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2 electrons + 2H+
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whihc electron transport chain component is not membrane associated
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cytochrome C, it is a soluble protein
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Describe the first step in the ETC starting with NADH
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electrons are removed from NADH by the enzyme complex NADH dehydrogenase which contains two redox carries FeS and FMN
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Describe the first complex of the ETC, NADH dehydrogenase
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removes the electrons from NADH using FeS and FMN
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What happens next in the ETC after NADH dehydrogenase takes the electrons from NADH (the same step occurs to the FADH2 in succinate dehydrogenase)
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coenzyme Q, a mobile carrier accepts the electrons from NADH dehydrogenase or from the FADH2 of succinate dehydrogenase and transfers them to ubiquinol cyt c reductase
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Ubiquinol Cyt C reductase accepts electrons from NADH dehydrogenase of FADH2 in succinate dehydrogenase. What happens within this complex
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The electrons are stepped down from cytb to FeS to Cyt c1.
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After the electrons are stepped down from cyt b to FeS to cyt c1 in ubiquinol Cyt C reductase, what happens to them
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they are transfer to cyt c, another mobile electron carrier
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What happens in the ETC after the electrons are transfered to cyt C from ubiquinol CytC reductase
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Cyt C carries the electrons to the last enzyme complex, cytochrome oxidase.
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What occurs in the last enzme complex of the ETC, cytochrome oxidase
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The electrons are transfered from Cu2+ to Cyt a to Cyt a3
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What happens to the electrons in the ETC after they finishing stepping down in cytochrome oxidase
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they are transfered to oxygen, the final electron acceptor
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How does cyanide inhibit the ETC
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it tightly binds to Cyt A3, the second to last electron carrier and inhibits transfer to oxygen
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describe the direction of proton transport that is coupled to the ETC
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protons are pumped from the matrix side of the inner mitochondrial membrane and released to the inner membrane space
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How do uncouplers like dinitrophenol effect oxidative phosphorylation
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they carry the H+ across the inner mitochondrial membrane and bypass ATP synthase. They diffuse the gradient and "short circut" the system. Note that the ETC is still functioning fine
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How many electrons are needed to drive the syntehsis of ~1 ATP molecule
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2
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How many ATP are produced per NADH molecule that enters the ETC
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3
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How many ATP are synthesized per FADH2
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2 (the electrons bypass the NADH dehydrogenase compled and bypass a step)
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Describe the transport of ADP and ATP across the inner mitochondrial membrane
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a translocase protein promotes the transport of ADP into the mitochonrial matrix in exchange for ATP being transported out into the cytoplasm
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Describe the respiratory control of the ETC
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The rate of eletron transport is indirectly controlled by the availability of ADP to phosphorylate. When ADP is low (ATP is high) electron transport is slowed because the protons pumped out by the electron transport system cannot reenter the mitochondria via ATPsynthase. The proton gradient thermodynamically prevents further proton pumping and the coupled electron transport reactions by the ETS. This prevents nurtient waste when ATP is plentiful.
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How many ATP molcules are produce per pyruvate molecule before ETC
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1 NADH from PDH X3 ATP
3 NADH from TCA X3 ATP 1 FADH2 from TCA X2 ATP 1 GTP from TCA X 1 ATP = 15 ATP |
