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Pentose Phosphate Pathway quiz

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  • What is the primary starting material for the pentose phosphate pathway?
    The primary starting material is glucose 6 phosphate.
  • What are the two main products generated from glucose 6 phosphate in the pentose phosphate pathway?
    The pathway generates 2 NADPH and ribulose 5 phosphate.
  • How does the pentose phosphate pathway differ from glycolysis in terms of glucose oxidation?
    The pentose phosphate pathway can fully oxidize glucose, while glycolysis only partially oxidizes it.
  • What is the structural difference between NADPH and NADH?
    NADPH has a phosphate group that NADH does not.
  • Does NADPH participate directly in oxidative phosphorylation?
    No, NADPH does not participate directly in oxidative phosphorylation.
  • Which enzyme catalyzes the conversion of glucose 6 phosphate to 6-phosphogluconolactone?
    Glucose 6 phosphate dehydrogenase catalyzes this reaction.
  • What is the role of lactonase in the pentose phosphate pathway?
    Lactonase breaks the lactone ring, converting 6-phosphogluconolactone to 6-phosphogluconate.
  • Which enzyme produces ribulose 5 phosphate and NADPH from 6-phosphogluconate?
    6-phosphogluconate dehydrogenase produces ribulose 5 phosphate and NADPH.
  • What is the function of phosphopentose isomerase in the pathway?
    Phosphopentose isomerase converts ribulose 5 phosphate to ribose 5 phosphate.
  • What are the two types of enzymes that transfer carbon units in the pentose phosphate pathway?
    Transketolases transfer 2-carbon units, and transaldolases transfer 3-carbon units.
  • Which cofactor is used by transketolases during carbon transfer?
    Transketolases use thiamine pyrophosphate as their transfer agent.
  • What two 5-carbon sugars are formed from ribulose 5 phosphate?
    Ribulose 5 phosphate can be converted to ribose 5 phosphate and xylulose 5 phosphate.
  • What is the significance of glyceraldehyde 3 phosphate (G3P) in the pentose phosphate pathway?
    G3P is a product that can be fed into other metabolic pathways.
  • How does NADPH help prevent oxygen toxicity in cells?
    NADPH provides electrons for glutathione reductase, which reduces glutathione and helps convert hydrogen peroxide to water.
  • How does excess NADPH regulate the pentose phosphate pathway?
    Excess NADPH inhibits glucose entry into the pathway via feedback inhibition.