Question

Carbohydrates are important biomolecules. They are also called saccharides C (H2O) Simple sugars are polyhydroxylated (OH) aldehydes and ketones (C=O). There are multiple classifications, based on length of parent carbon chain, the position of C=0 in chain and the stereochemistry. Complex carbohydrates have multiple simple sugars linked together and polysaccharide are polymers of simple sugars (a) (1) Identify the anomeric carbon in the following structure? Is it in the a or B form? H OH HOTT H OHH OH (ii) Draw the open chain form of the molecule. What is a monosaccharaide, a disaccharide and a polysaccharide? Give an example of a disaccharide showing the link of the monomers through the anomeric carbon. (c) (i) Draw the general chemical structure of Cellulose (ii) Draw the general chemical structure of glycogen (starch) (iii) What is the chemical nature of the structural difference between cellulose and glycogen (starch).

Answer 1

3a)I) It is alpha ($\alpha$) because OH on anomeric carbon is pointing downward.

II) All groups which are downward will go on right side in open chain structure.

b) I) Monosaccharide are sugar which don't undergo Hydrolysis.

Disaccharides are sugar which on Hydrolysis give two simple sugar units.

Polysaccharide are sugar which on Hydrolysis give may simple sugar units.

II) Maltose is a Disaccharide linked through anomeric carbon of one sugar.

всн ,он Gусosidie всH,Он linkage о Он Он но Он Seanne vih msoрar CS Он Он

c) I) Cellulose structure :

но но O н н н H ОН н н ОН H н Он ОН Scanned with Cellulose CamScanner H O I

II) Glycogen structure :

CHOH H OH OH CHOH H OH OH OH Glycogen Scanned with CS CamScanner

III) Cellulose is linear polymer whereas Glycogen is branched polymer. Cellulose contain 1,4-glycosidic bond and Glycogen contain 1,4- as well as 1,6-glycosidic bond.

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