A common disaccharide is composed of a 6-membered pyranose ring and a 5-membered furanose ring connected by a glycosidic linkage between their anomeric carbons. In its standard Haworth projection, the oxygen linkage at the C1 of the pyranose ring points down (trans to the terminal -CH₂OH group). For the furanose ring, the anomeric carbon (C2) has its -CH₂OH group pointing down and the glycosidic oxygen linkage pointi

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The disaccharide described is sucrose, which consists of D-glucose and D-fructose units. For the 6-membered pyranose ring (glucose), the oxygen linkage at the anomeric C1 carbon points down, which is trans to the terminal -CH₂OH group. This corresponds to the -anomer, so the unit is -D-glucopyranose. For the 5-membered furanose ring (fructose), the anomeric C2 carbon has the glycosidic oxygen pointing up, which is cis to the terminal -CH₂OH group at C5. This corresponds to the -anomer, making the unit -D-fructofura