BIOC 299 Chapter 21 Exam Questions And
Complete Answers
ATP synthase (Complex V, F1F0 ATPase) - answer - molecular assembly of the inner
mitochondrial membrane responsible for the respiratory-chain-driven synthesis of ATP
- the corresponding E in chloroplasts is called the CF1-CF0 complex
proton-motive force - answer - the energy inherent in the established proton gradient
during the functioning of the respiratory chain
- consists of a membrane potential as well as a chemical gradient
electron-transport chain - answer - 4 large protein complexes embedded in the inner
mitochondrial membrane
- the oxidation-reduction reactions that allow the flow of electrons from NADH & FADH2
to oxygen take place in these complexes
glycerol 3-phosphate shuttle - answer - a pathway that transfers electrons from
cytoplasmic NADH into the mitochondria
- dihydroxyacetone phosphate (DHAP) is reduced by NADH to glycerol 3-phosphate,
which enters the mitochondria & is oxidized to FADH2 & DHAP, which leaves the
mitochondria
malate-aspartate shuttle - answer a reversible shuttle, found in the liver & heart, used to
transport electrons from cytoplasmic NADH to mitochondrial NAD+
ATP-ADP translocase (adenine nucleotide translocase, ANT) - answer a transport
protein in the inner mitochondrial membrane that carries ADP into the mitochondria &
ATP out in a coupled fashion
cellular respiration - answer the generation of high-transfer-potential electrons by the
CAC, their flow through the respiratory chain, & the accompanying synthesis of ATP
respiratory (acceptor) control - answer - tight coupling or coordination of the oxidation
of reduced cofactors (NADH & FADH2) in the ETC & the phosphorylation of ADP to yield
ATP in the mitochondrion
- such control ensures that the rate of the CAC, where reduced cofactors are generated,
corresponds to the demand for ATP
Human beings have only about 250 g of ATP, but even a coach potato needs about 83 kg
of ATP to open that bag of chips & use the remote - how is this discrepancy between
, requirements & resources reconciled? - answer the ATP is recycled by processes that
generate ATP, most notably oxidative phosphorylation
What is the yield of ATP when each of the following substrates is completely oxidized to
CO2 by a mammalian cell homogenate?
Assume that glycolysis, the CAC, & oxidative phosphorylation are fully active
1. pyruvate
2. lactate
3. fructose 1,6-bisphosphate
4. phosphoenolpyruvate
5. galactose
6. dihydroxyacetone phosphate - answer 1. 12
2. 15
3. 32
4. 13.5
5. 30
6. 16
These answers are readily obtained if one remembers the ATP yields from the various
parts of glycolysis & remembers that (a) cytoplasmic NADH yields only 1.5 ATP, (b)
pyruvate → acetyl CoA + NADH yields 2.5 ATPs, (c) each acetyl CoA traversing the CAC
yields 10 ATP (7.5 from 3 NADH, 1.5 from 1 FADH2 & 1 from GTP), (d) galactose requires
1 ATP for activation, just as glucose does
What is the effect of each of the following inhibitors on ET & ATP formation by the
respiratory chain?
1. azide
2. atractyloside
3. rotenone
4. DNP
5. carbon monoxide
6. antimycin A - answer 1. blocks electron transport & proton pumping at site 3
2. blocks electron transport & ATP synthesis by inhibiting the exchange of ATP & ADP
Complete Answers
ATP synthase (Complex V, F1F0 ATPase) - answer - molecular assembly of the inner
mitochondrial membrane responsible for the respiratory-chain-driven synthesis of ATP
- the corresponding E in chloroplasts is called the CF1-CF0 complex
proton-motive force - answer - the energy inherent in the established proton gradient
during the functioning of the respiratory chain
- consists of a membrane potential as well as a chemical gradient
electron-transport chain - answer - 4 large protein complexes embedded in the inner
mitochondrial membrane
- the oxidation-reduction reactions that allow the flow of electrons from NADH & FADH2
to oxygen take place in these complexes
glycerol 3-phosphate shuttle - answer - a pathway that transfers electrons from
cytoplasmic NADH into the mitochondria
- dihydroxyacetone phosphate (DHAP) is reduced by NADH to glycerol 3-phosphate,
which enters the mitochondria & is oxidized to FADH2 & DHAP, which leaves the
mitochondria
malate-aspartate shuttle - answer a reversible shuttle, found in the liver & heart, used to
transport electrons from cytoplasmic NADH to mitochondrial NAD+
ATP-ADP translocase (adenine nucleotide translocase, ANT) - answer a transport
protein in the inner mitochondrial membrane that carries ADP into the mitochondria &
ATP out in a coupled fashion
cellular respiration - answer the generation of high-transfer-potential electrons by the
CAC, their flow through the respiratory chain, & the accompanying synthesis of ATP
respiratory (acceptor) control - answer - tight coupling or coordination of the oxidation
of reduced cofactors (NADH & FADH2) in the ETC & the phosphorylation of ADP to yield
ATP in the mitochondrion
- such control ensures that the rate of the CAC, where reduced cofactors are generated,
corresponds to the demand for ATP
Human beings have only about 250 g of ATP, but even a coach potato needs about 83 kg
of ATP to open that bag of chips & use the remote - how is this discrepancy between
, requirements & resources reconciled? - answer the ATP is recycled by processes that
generate ATP, most notably oxidative phosphorylation
What is the yield of ATP when each of the following substrates is completely oxidized to
CO2 by a mammalian cell homogenate?
Assume that glycolysis, the CAC, & oxidative phosphorylation are fully active
1. pyruvate
2. lactate
3. fructose 1,6-bisphosphate
4. phosphoenolpyruvate
5. galactose
6. dihydroxyacetone phosphate - answer 1. 12
2. 15
3. 32
4. 13.5
5. 30
6. 16
These answers are readily obtained if one remembers the ATP yields from the various
parts of glycolysis & remembers that (a) cytoplasmic NADH yields only 1.5 ATP, (b)
pyruvate → acetyl CoA + NADH yields 2.5 ATPs, (c) each acetyl CoA traversing the CAC
yields 10 ATP (7.5 from 3 NADH, 1.5 from 1 FADH2 & 1 from GTP), (d) galactose requires
1 ATP for activation, just as glucose does
What is the effect of each of the following inhibitors on ET & ATP formation by the
respiratory chain?
1. azide
2. atractyloside
3. rotenone
4. DNP
5. carbon monoxide
6. antimycin A - answer 1. blocks electron transport & proton pumping at site 3
2. blocks electron transport & ATP synthesis by inhibiting the exchange of ATP & ADP
