[Campbell Biology P.120] Referring to Figure 5.7 and the associated text, what is the fundam... | Practice Question

Referring to Figure 5.7 and the associated text, what is the fundamental structural difference between alpha-glucose and beta-glucose that dictates their role in forming starch and cellulose, respectively?

  • A: Alpha-glucose is a six-carbon sugar, while beta-glucose is a five-carbon sugar.
  • B: The position of the hydroxyl group attached to the number 1 carbon differs: below the ring in alpha-glucose and above the ring in beta-glucose.
  • C: Alpha-glucose forms 1-6 glycosidic linkages, while beta-glucose forms only 1-4 glycosidic linkages.
  • D: Alpha-glucose is found exclusively in animals, whereas beta-glucose is found only in plants.

Explanation

Figure 5.7a clearly illustrates the difference in the position of the hydroxyl group highlighted in blue attached to the number 1 carbon between alpha-glucose and beta-glucose. The text elaborates that this subtle difference dictates the overall structure and properties of the resulting polymers, starch all alpha configuration and cellulose all beta configuration, with alternating orientations .