Carbohydrates -I- OH OH H H HO CH 2 OH H H H OH O Energy molecules

General Characteristics Carbohydrates = Carbon (C) + Hydrates (OH).Carbohydrates = Carbon (C) + Hydrates (OH). All carbohydrates are compounds composed of (at least) C, H, and OAll carbohydrates are compounds composed of (at least) C, H, and O The general formula for a carbohydrate is: (CH 2 O) n The general formula for a carbohydrate is: (CH 2 O) n Not all carbohydrates have this empirical formula (e.g. deoxysugars, aminosugars, etc.)Not all carbohydrates have this empirical formula (e.g. deoxysugars, aminosugars, etc.) Carbohydrates are the most abundant compounds found in nature.Carbohydrates are the most abundant compounds found in nature. Produced by photosynthesis in plants from CO2, H2O and energy.Produced by photosynthesis in plants from CO2, H2O and energy. Are oxidized in living cells (respiration) to produce CO 2, H 2 O, and energy.Are oxidized in living cells (respiration) to produce CO 2, H 2 O, and energy.

Carbohydrate Functions Carbohydrates can be: Sources of energySources of energy Intermediates in the biosynthesis of other basic biomolecules (fats and proteins)Intermediates in the biosynthesis of other basic biomolecules (fats and proteins) Structural tissues in plants and in microorganisms (cellulose, lignin, murein)Structural tissues in plants and in microorganisms (cellulose, lignin, murein) Involved in biological transport, cell-cell recognition, activation of growth factors, modulation of the immune systemInvolved in biological transport, cell-cell recognition, activation of growth factors, modulation of the immune system

Classification: Carbohydrates are placed in to one of three categories, depending on the number of monosaccharide units, or residues, they contain. Monosaccharides, contain a single monosaccharide residue. Monosaccharides, contain a single monosaccharide residue. Oligosaccharides, contain 2 to 10 monosaccharide residues. Oligosaccharides, contain 2 to 10 monosaccharide residues. These include the disaccharides, which contain 2 monosaccharide residues. These include the disaccharides, which contain 2 monosaccharide residues. Polysaccharides, which contain more than 10 monosaccharide residues. Polysaccharides, which contain more than 10 monosaccharide residues. These may contain thousands of monosaccharide residues. These may contain thousands of monosaccharide residues.

Monosaccharides Monosaccharides are polyhydroxy aldehydes or ketones. Monosaccharides are polyhydroxy aldehydes or ketones. Monosaccharides contain 3 to 7 carbon atoms. Monosaccharides contain 3 to 7 carbon atoms.

Monosaccharides Monosaccharides are classified according to the number of carbons and whether they contain an aldehyde or ketone. The “-ose” ending is used to designate carbohydrates. The “-ose” ending is used to designate carbohydrates.

Monosaccharides Monosaccharides contain chiral carbon atoms. This is what accounts for the large number of different monosaccharides. This is what accounts for the large number of different monosaccharides. For each chiral carbon, n, a monosaccharide has 2 n stereoisomers. For each chiral carbon, n, a monosaccharide has 2 n stereoisomers. These will be divided among 2 n /2 pairs of enantiomers. These will be divided among 2 n /2 pairs of enantiomers. Glucose contains 4 chiral carbons Glucose contains 4 chiral carbons Glucose has 2 4 = 16 stereoisomers Glucose has 2 4 = 16 stereoisomers These stereoisomers can be grouped into 16/2 = 8 pairs of enantiomers. These stereoisomers can be grouped into 16/2 = 8 pairs of enantiomers. Glucose contains 4 chiral carbons Glucose contains 4 chiral carbons Glucose has 2 4 = 16 stereoisomers Glucose has 2 4 = 16 stereoisomers These stereoisomers can be grouped into 16/2 = 8 pairs of enantiomers. These stereoisomers can be grouped into 16/2 = 8 pairs of enantiomers.

Monosaccharides Fischer projections are used to distinguish the different stereoisomers. The letters D and L are used to distinguish between the members of a pair of enantiomers. The letters D and L are used to distinguish between the members of a pair of enantiomers. The D or L designation is based on the chiral carbon furthest from the carbonyl carbon. The D or L designation is based on the chiral carbon furthest from the carbonyl carbon. Fischer projection:

Monosaccharides Important monosaccharides. pentoses and hexoses are the most abundant pentoses and hexoses are the most abundantPentoses D-ribose and D-2-deoxyribose are found in DNA, RNA and nucleotides such as FADH 2 and NADH D-ribose and D-2-deoxyribose are found in DNA, RNA and nucleotides such as FADH 2 and NADH

Epimers Pairs of monosaccharides different only in configuration around only one specific C-atom.Pairs of monosaccharides different only in configuration around only one specific C-atom. For example, glucose and galactose are C-4 epimers—their structures differ only in the position of the - OH group at carbon 4.For example, glucose and galactose are C-4 epimers—their structures differ only in the position of the - OH group at carbon 4.

Monosaccharides Important monosaccharides. Hexoses D-glucose (dextrose or blood surgar) - major metabolite and storage form of chemical energy. D-glucose (dextrose or blood surgar) - major metabolite and storage form of chemical energy. D-galactose - combines with glucose to produce lactose (milk sugar) D-galactose - combines with glucose to produce lactose (milk sugar) D-fructose (fruit sugar) - major metabolite and sweetest tasting natural sugar. D-fructose (fruit sugar) - major metabolite and sweetest tasting natural sugar. fructose is a ketose fructose is a ketose

Monosaccharides Monosaccharide derivatives Amino sugars. Amino sugars. One or more -OH’s are replaced with -NH 2 ’s One or more -OH’s are replaced with -NH 2 ’s Often these are acetylated to form amides. Often these are acetylated to form amides. Arthritis relief?? Arthritis relief??

Monosaccharides Monosaccharide derivatives Carboxylic acid sugars. Carboxylic acid sugars. The ketone, aldehyde, or primary alcohol is oxidized to a carboxylic acid. The ketone, aldehyde, or primary alcohol is oxidized to a carboxylic acid.

15 Shown below is the Fischer projection for sorbose Is the structure shown A)D-sorbose B)L-sorbose Draw and name the α and β ring forms for sorbose α- D -sorbofuranose β- D -sorbofuranose Question:

16 Question: Shown to the right is the Fischer projection for galactose Is the structure shown A)D -galactose B)L -galactose Draw and name the α and β ring forms for galactose β- L -galactopyranose α- L -galactopyranose

إن الله وملائكتــه يصلــون على النبي يــأيــها الذيـن آمنوا صلــوا عليه وسلمـــوا تسليمـــا