Question

How to make carbohydrate molecule that is labeled

Answer 1

Radioactive carbohydrates such as starch, glucose, fructose , sucrose can be prepared by exposing plants in an environment enriched with radioactive CO2 in presence of light.

After a few photosynthetic cycles the leaves of the plants are dipped into dilute alcohol. The carbohydrates are insoluble in alcohol and thus will be precipitated in the insoluble fraction which can be isolated and mixed with acid. This will cause hydrolysis reaction producing glucose, fructose, sucrose in crystalline form. Further hydrolysis of sucrose will produce more amount of radiolabelled glucose and fructose.