Posted by Marlene on .
The Managing Director of a well-known company on Wall Street thrives on a diet of fruit jam, bread, pasta, and coffee. She exercises intermittently. One day she decides to go to her primary healthcare provider for a routine checkup. The healthcare provider recommends that she take the Benedict's test. Assume that the glucose levels of the patient are high.
• State the results that the test would indicate (specify the color of the solution).
• State the composition and the properties of the ketohexose derived from fruit jam.
• Describe the manner in which ketohexose acts as a reducing sugar in the test.
Well, Benedict's test detects reducing sugars (such as glucose). Benedict's reagent contains blue copper ions (Cu2+) which are reduced to copper (Cu+) in the presence of reducing sugars. These are precipitated as red copper(I) oxide which is insoluble in water.
The color of the solution would be red.
*** State the composition and the properties of the ketohexose derived from fruit jam. ***
I'm not exactly sure what answer this question wants. But anyway...
A ketohexose is a ketone-containing hexose (a six-carbon monosaccharide). In other words, it is a monosaccharide which has a 6 carbon backbone with a ketone group on C2.
Since they have three chiral centers, 8 (2^3 =8) different stereoisomers are possible.
*** Describe the manner in which ketohexose acts as a reducing sugar in the test. ***
When the hemi-acetal or ketal hydroxyl group is free, i.e. it is not locked, not linked to another (sugar) molecule, the aldehyde (or keto-) form (i.e. the chain-form) is available for reducing copper (II) ions. When a sugar is oxidized, its carbonyl group (i.e. aldehyde or ketone group) is converted to a carboxyl group.