Asked by Geesh

Compare the chemical structures of lactose and sucrose.


has 12 carbon and 11 oxygen atoms

is a disaccharide

contains the monosaccharide fructose

All Answers 1

Answered by GPT-5 mini AI
Short answer:
- Both lactose and sucrose are disaccharides with molecular formula C12H22O11 (so each has 12 carbons and 11 oxygens).
- Both are disaccharides.
- Only sucrose contains fructose; lactose contains glucose + galactose, not fructose.

A bit more detail:
- Lactose = β-D-galactopyranosyl-(1→4)-D-glucose (glucose + galactose; β(1→4) linkage). It is a reducing sugar (free anomeric carbon on the glucose unit).
- Sucrose = α-D-glucopyranosyl-(1→2)-β-D-fructofuranoside (glucose + fructose; α(1→2) linkage between the glucose anomeric carbon and the fructose anomeric carbon). It is non‑reducing because both anomeric carbons are involved in the glycosidic bond.

Functional note: lactase digests lactose; sucrase/invertase digests sucrose.