Which of the following statements about the electron transport chain is NOT true

Question

Which of the following statements about the electron transport chain is NOT true? Four multiprotein complexes are responsible for coupling electron transport to proton pumping. Cytochrome c oxidase passes four electrons to oxygen to yield two water molecules and complete the electron transport chain. Prosthetic groups bound to proteins involved in electron transport include heme, iron sulfur clusters, and ubiquitin. Electrons may enter the electron transport chain at either complex I or complex II. _____ is the carbon-containing compound produced by glycolysis. Pyruvate CO2 Acetyl CoA Glucose
In the overall reaction for cellular respiration, glucose is: oxidized to CO_2.<br /> reduced to CO_2.<br /> oxidized to O_2.<br /> reduced to O_2.<br /> Phosphofructokinase is _____ active in the glycolytic pathway when the levels of ATP are high in the cell because _____. less; ATP is a competitive inhibitor more; ATP stimulates phosphofructokinase through allosteric interactions more; lower ADP levels activate phosphofructokinase less; ATP is an allosteric inhibitor NADH-CoQ reductase and CoQH2-cytochrome c reductase each use the energy derived from electron transfer to transport _____ the mitochondrial matrix. two protons into four protons into two protons out of four protons out of During ATP synthesis, protons move down their electrochemical gradient through: a proton channel protein. CoQH2 cytochrome c reductase. the F1 complex of ATP synthase. the F0 complex of ATP synthase.
Glucose is not the only energy-containing molecule that can enter cellular respiration pathways. Which food source is MOST likely to be catabolized and supply the citric acid cycle with Acetyl CoA? fats carbohydrates amino acids DNA Which of the following statements about the electron transport chain is NOT true? Four multiprotein complexes are responsible for coupling electron transport to proton pumping. Cytochrome c oxidase passes four electrons to oxygen to yield two water molecules and complete the electron transport chain. Prosthetic groups bound to proteins involved in electron transport include heme, iron sulfur clusters, and ubiquitin. Electrons may enter the electron transport chain at either complex I or complex II.

Explanation / Answer

1. Prosthetic groups bound to proteins involved in electron transport include heme, iron sulfur clusters, and ubiquitin is the incorrect statement. Ubiqutin is not a prosthetic group bound to respiratory chain enzymes. It is a small protein which targets proteins for degradation

2. Pyruvate is the carbon containing produced during glycolysis. It is the end product of glycolysis .

3. In overall reaction for  cellular respiration, glucose is: oxidized to CO2. Glucose is first oxidized to pyruvate, pyruvate is then oxdized to acetyl -CoA releasing CO2. Acetyl-CoA then enters citric acid cycle to produce two molecules of CO2

4. Phosphofructokinase is less active in the glycolytic pathway when the levels of ATP are high in the cell because ATP is an allosteric inhibitor. When there is abundance of ATP in the cell it would not want to waste energy on glycolysis . ATP , which is a product of glycolysis allosterically regulates the first committed irreversible step of glycolysis i.e fructose-6-phosphate to  fructose-1, 6-phosphate by inhibiting the enzyme phosphofructokinase catalyzing this reaction. In allosteric inhibition the regulator ATP in this case, binds to a regulatory site and changes the shape of the enzyme so it can no longer bind to its substrate (fructose-6-phosphate in this case)

5. NADH-CoQ reductase and CoQH2-cytochrome c reductase each use the energy derived from electron transfer to transport four protons out of the mitochondrial matrix. Per 2 electrons transported by these complexes four protons are translocated to the intermembrane space. These protons create a proton motive force in the intermembrane space, which is used to synthesize ATP as these protons flow back into the matrix via ATP synthase.

7.Glucose is not the only energy-containing molecule that can enter cellular respiration pathways. Which food source is MOST likely to be catabolized and supply the citric acid cycle with Acetyl CoA.

Answer : Fat oxidation produces acetyl CoA which can enter the citric acid cycle .

6. During ATP synthesis, protons move down their electrochemical gradient through the F0 complex of ATP synthase. F0 is a inner mitchondrial transmembrane protein complex which form H+ (proton) channel. It is associated with F1 ATPase which synthesis ATP .

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