BIO202 Full Merged Slides for Printing

VU Medical Zone · Admin: · Amaan Khan · Biochemistry-I · BIO 202 ppt

• Carbohydrates are polyhydroxy aldehydes or ketones, or substances that yield such compounds on hydrolysis
• Many, but not all, carbohydrates have the empirical formula(CH2O)n; some also contain nitrogen, phosphorus or sulfur

Classification

• Carbohydrates are classified into four major groups:

• Disaccharides (simple sugars) are those which cannot be hydrolyzed further into simpler forms • The backbones of common monosaccharides are unbranched carbon chains in which all the carbon atoms are linked by single bonds

• In the open-chain

form, one of the carbon atoms is double-bonded to an oxygen atom to form

a carbonyl group

• Each of the other carbon atoms has a hydroxyl group

• If the carbonyl group is at an end of the carbon chain (that is, in an aldehyde group) the monosaccharide is an aldose
• If the carbonyl group is at any other position (in a ketone group) the monosaccharide is a

ketose

• The simplest

monosaccharides are the two three-carbon trioses: – Glyceraldehyde,an aldotriose

a ketotriose • The carbons of a sugar are numbered beginning at the end of the chain nearest the carbonyl group

• All common

and disaccharides have names ending with the suffix “-ose.” • Ketoses are designated by inserting "ul" into the name of a corresponding aldose • For example, ribulose is the ketopentose corresponding to the aldopentose ribose • There are a few exceptions however, for example, fructose and dihydroxyacetone

• General formula

Trioses C3H6O3 Tetroses C4H8O4 Aldosugars Glyceraldehyde Erythrose Ketosugars

Erythrulose

Pentoses C5H10O5 Ribose Hexoses C6H12O6 Glucose Ribulose Fructose

• Monosaccharides can be subdivided further

depending upon:

• Number of carbon atoms
• Whether aldehyde or ketone groups are present

as aldoses or ketoses • The hexoses which include the aldohexose Dglucose and the ketohexose Dfructose, are the most common monosaccharides in nature