Lactate fermentation occurs a. in the presence of pyruvate and oxygen. b. in the
ID: 89396 • Letter: L
Question
Lactate fermentation occurs a. in the presence of pyruvate and oxygen. b. in the presence of pyruvate and absence of enough oxygen C. in the presence of oxygen and absence of pyruvate. d. with oxidative phosphorylation. ATP synthase enzymes are embedded within the inner membrane of the mitochondrion. ATP synthases are able to generate ATP following the flow a. of electrons through the enzyme. b. of hydrogen ions through the enzyme. c. of NADH through the enzyme d. of ATP through the enzyme. The ATP made directly during glycolysis is generated with the help of a. kinase enzymes. b. dehydrogenase enzymes. c NADH. d. NAD+.Explanation / Answer
Ans. 5. Correct option. b
Note that glycolysis (conversion of glucose into pyruvate) is independent of O2- i.e. glycolysis takes place irrespective of presence or absence of O2.
In presence of O2, the pyruvate enters citric acid cycle. The products of TCA (NADH and FADH2) further enter electron transport chain to establish proton gradient. The proton gradient is later harvested in the form of ATP through oxidative phosphorylation.
Pyruvate enters fermentation (say, lactate or ethanol fermentation) when the cell lacks O2 or O2 supply is depleted below a threshold. Therefore, option b is correct.
#6. Correct option b.
See #5, as mentioned the energy of pyruvate is used to establish proton (H+) gradient across the inner mitochondrial membrane, the higher [H+] being in the intermembrane space. The pH difference across the inner membrane forms a Chemiosmotic potential (a form of potential energy) which is harvested in form of ATP when H+ flows from its higher to lower concentration (from intermembrane space to matrix) through the enzyme ATP synthase.
#7. Correct option. a
ATP is directly made (substrate level phosphorylation) during glycolysis at two steps- one catalyzed by phosphoglycerate kinase and the other catalyzed by pyruvate kinase.
Dehydrogenases remove H2 from a molecular coupled with formation of NADH or FADH2.
NAD+ is reduced to NADH during glycolysis, but does not produces ATP directly.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.