Question

For biochemistry:

Why would 0.3umoles/mL of lactose gave a similar value for the Nelson Test to the value of glucose at the same concentration. They both had very similar absorbance.

Answer 1

Dietary lactose and sucrose, and maltose derived from digestion of starch, diffuse in the small intestinal lumen and come in contact with the surface of absorptive epithelial cells covering the villi where they engage with brush border hydrolases.

• lactase cleaves lactose into a glucose and a galactose.
• At long last, we're ready to actually absorb these monosaccharides. Glucose and galactose are taken into the enterocyte by cotransport with sodium using the same transporter. The galactose is taken out from there and therefore only glucose remains which makes the absorbance of lactose equal to glucose.