Carbohydrates and D-Glucose Structure

Questions and Answers

What is the chemical formula for dihydroxyacetone?

CH2OH - C = O - CH2OH

Which of the following statements is true about enantiomers?

They are superimposable on their mirror images.

They are caused by the presence of chiral carbons.

Both B and C. (correct)

They are optical isomers.

D-glucose and L-glucose are the same compound.

False

What is the classification of D-fructose?

Ketohexose Signup and view all the answers

Glucose is commonly known as _ or _ sugar.

dextrose, grape Signup and view all the answers

How is the number of optical isomers calculated?

2^n Signup and view all the answers

What is the specific rotation of a chiral compound in the context given?

30° Signup and view all the answers

Fructose is less soluble than other sugars.

False Signup and view all the answers

Match the following terms with their definitions:

Chiral Carbons = Carbons attached to four different groups/atoms Optical Activity = Ability to rotate polarized light Epimers = Type of isomer that differs at one chiral center Dextrose = Another name for D-glucose Signup and view all the answers

Study Notes

Carbohydrates Overview

All carbohydrates in the human body are in the D-form, with the exception of dihydroxyacetone.
Chemical formula for dihydroxyacetone: $CH_2OH - C = O - CH_2OH$.
Dihydroxyacetone lacks chiral carbons.

Chiral Carbons and Enantiomers

The position of the -OH group on the chiral carbon atom farthest from C=O determines D- or L-type configurations.
D-glucose and L-glucose are two types of glucose.

Glucose Structures

D-Glucose Structure:
- CHO
- H-C-OH
- HO-C-H
- H-C-OH
- H-C-OH
- CH2OH
L-Glucose Structure:
- CHO
- HO-C-H
- H-C-OH
- HO-C-H
- HO-C-H
- CH2OH

Hexoses

D-Galactose:
- Formula: $C_6H_{12}O_6$
- Structure includes multiple -OH groups.
Glucose's structure is identical in chemical formula to other hexoses like galactose.

Optical Activity

Compounds with chiral carbons are optically active and termed optical isomers.
Enantiomers are stereoisomers that are non-superimposable on their mirror images, caused by chiral carbons.

D-Glucose Characteristics

Also known as dextrose or grape sugar; found in blood and tissue fluids, classified as blood sugar.
Normal fasting blood glucose levels: 3.9-5.5 mmol/l.
Does not require digestion and can be administered intravenously.

Optical Isomers

The number of optical isomers equals $2^n$, where n is the number of chiral carbons.
Glucose requires no digestion, providing immediate energy.

Optical Activity Mechanism

Chiral compounds rotate polarized light: clockwise (+) or counter-clockwise (-).
Specific rotation example: 30°.

D-Fructose

Formula: $C_6H_{12}O_6$.
Structure includes diverse functional groups.
Classified as a ketohexose with 8 optical isomers.
Commonly referred to as levulose or fruit sugar; naturally found in fruits and honey.
Fructose is the sweetest and most soluble sugar, often used as a dietary sugar.

Monosaccharide Structures

Monosaccharides with five or more carbon atoms exist in equilibrium between open-chain and cyclic forms, with cyclic structures being predominant.
Haworth projections represent the ring structure of monosaccharides.

Description

This quiz covers the essential details regarding carbohydrates in the human body, focusing specifically on dihydroxyacetone and the classifications of D- and L-glucose. Participants will explore the structural characteristics and chemical formulas associated with these carbohydrates, enhancing their understanding of carbohydrate chemistry.