CARBOHYDRATES Monosaccharides Disaccharides Polysaccharides (homo-) Polysaccharides (hetero-)

What is a carbohydrate? Ans: A carbohydrate is a polyhydroxy aldehyde or ketone or a compound that gives rise to such on hydrolysis 1. It must have more than one hydroxy group 2. It must have either an aldehyde or a ketone functional group 3. It can be a large molecule made up of repeating units with the above characteristics What is a monosaccharide? 1. Otherwise known as a simple sugar, it’s a carbohydrate that cannot be converted to a smaller molecule by simple hydrolysis What is a polysaccharide? 1. Otherwise known as a complex carbohydrate, it’s a carbohydrate molecule constructed of a smaller repeating unit, homo (same unit) or hetero (different units).

See Strategies pp

C H O C O H C H 2 O H H C H O C H 2 O H C H O H SIMPLEST CARBOHYDRATE CARBONYL GROUP CHIRAL CENTER PRIMARY ALCOHOL

CHO C C CH 2 OH OH Reducing group D orientation Primary alcohol Primary alcohol Primary alcohol Reducing group CH 2 OH C=O C CH 2 OH OH Aldose Ketose Anatomy of a Monosaccharide

Simplest Carbohydrate - Quiz CH 2 OH C=O CH 2 OH Is this a polyhydroxy aldehyde? NO Is this a polyhydroxy ketone? YES Is this a D sugar? Is this a carbohydrate? YES NO Is this an L sugar? NO Why? No chiral center in the molecule Name? Dihydroxy Acetone

GLUCO GALACTO MANNO EPIMERS See carbohydrate tutorial on web See carbohydrate tutorial on web OH Group Configurations

C H O C O H CH 2 O H H CO HH C H O CO HH CHOH CH 2 O H CO HH C H O CHOH CH 2 O H CHOH C H O C H OH C H 2 O H A BC D D-SUGARS ENANTIOMERS DIASTEREOISOMERS L-SUGARS ENANTIOMERS

n= 2 n=3 4 Isomers = 2 n Total = 4 Total = 8 16 By specifying a sugar as D or L we need name only half of the total By specifying a sugar as D or L we need name only half of the total n = no. of chiral cntr

Anomeric carbon RING STRUCTURE OF SUGARS

OH IS ON SAME SIDE AS RING OXYGEN OH IS ON OPPOSITE SIDE OF RING OXYGEN ALPHA SUGARBETA SUGAR ANOMERS H - C - OH O * HO - C - H O *