Final answer:
The correct structure for β-d-fructose-6-phosphate is option (c) H₃C-CHOH-CHOH-CHOH-CHOH-CHOH-PO₃²⁻, which depicts a phosphorylated sugar in its linear form with a ketose configuration at C2 and a phosphate group at C1.
Step-by-step explanation:
The metabolism of monosaccharides such as glucose and fructose within the human body results in various phosphorylated sugars that are instrumental for energy extraction processes like glycolysis. A key intermediate of glycolysis is β-d-fructose-6-phosphate. The structure of this molecule is characterized by a chain of six carbon atoms, where the first carbon (C1) is attached to a phosphate group forming an ester bond, and the rest of the molecule resembles the linear form of fructose, with the exception that C6 has a hydroxyl (-OH) group, as opposed to the carbonyl (=O) function present in free fructose.
Now, looking at the provided options, we can eliminate (a) and (d) as they have a terminal aldehyde group (CHO) which would be characteristic of an aldose sugar, whereas fructose is a ketose sugar. Also, (b) lacks any phosphate group, which is essential for identifying a phosphorylated sugar. Therefore, option (c) H₃C-CHOH-CHOH-CHOH-CHOH-CHOH-PO₃²⁻ is the correct representation of β-d-fructose-6-phosphate because it has the ketose configuration at C2 and a phosphate group at C6. In the structure, the 'H₃C-' at the beginning denotes the methyl end (C6), and the 'CHOH-PO₃²⁻' at the end represents the C1 position where the phosphate group is attached.