Carbohydrates

Carbohydrate

• hydrate of carbon – Cn(H2O)m

• Glucose -blood sugar- C6H12O6 or C6(H2O)6

• Sucrose -table sugar- C12H22O11 or C12(H2O)11

• Not all carbohydrates have this exact form

– old habits die slow or sometimes never at all

Monosaccharides

• Formula CnH2nOn

• One carbon is either an aldehyde or ketone

• The suffix ose indicates that the molecule is a carbohydrate

• Use prefix to indicate number of carbons tri , tetr, pent, hex

• Aldose – contain an aldehyde group• Ketose – contain a ketone group

Monosaccharides

• Aldohexoses

Aldohexosesaldehyde function

six carbons

carbohydratesor

saccharides

other examples: ketotetrose, aldotriose, ketopentose

Fischer Projections

• Emil Fischer (late 1800’s)

– Side groups come out of the plane (towards you)– Vertical groups go back away from you

HHO

CHO

HHO

CH2OH

H OH

CHO

H OH

CH2OH

OHH

CHO

HHO

CH2OH

HO H

CHO

H OH

CH2OH

A B C D

Naming Aldotriose and aldotetrose

Remember ET goes home left at T

Naming AldoPentose

RAXL – Ribose, Araginose, Xylose, Lyxose

Right – Top – Middle – Top/Middle

Naming Aldohexoses

• All Altrose Gladly Make Gum in Gallon Tanks

• Bottom – all right

• 2 up – 4x4

• 3 up – 2x2 like Noahs Ark

• 4 up – alternate

R/S and D/L

• R = D - dextrorotatory• S = L - levarotatory• D – A monosaccharide with the

Penultimate OH group on the right in a Fischer Projection

• L - A monosaccharide with the penultimate OH group on the left in a Fischer Projection

OK, so what’s a penultimate????

Ketoses

• Note:

The ketone is located

on carbon #2

triose

tetrose

pentoses

hexoses

*

*

Penultimate is the nextTo last carbon

Amino Sugars

• Contain an NH2 group instead of an OH

• 1st three are common in nature

Cyclic structure of monsacharides

• It’s the hemiacetal reaction all over

• We draw them as Haworth Projections

• Practice practice practice

From yahoo images

Reactions of Monosacharides

• Practice

From yahoo images

The two Most Significant Sugars

• Ketose– D-Fructose– Known as “fruit

sugar”– Found combined with

glucosein the disaccharide sucrose

HO

D-fructose

CH 2O H

CH 2O H

O H

O

OH

•Aldose -D-glucose

-The most important monosaccharide -White solid -Formula C6H12O6

- Sugar used in our bodies

CH2OH

C

C

C

C

C

OH

OH

H

OH

H

O

H

HO

H

H

1

2

3

4

5

6

Multiple Sugars

• Monosaccharides – Single Carbohydrate unit• Disaccharides - two monosaccharides combined• Oligosaccharides - three to ten monosaccharides• Polsaccharide – More than ten monoscharides

Three Disaccharides

• Sucrose

• Lactose

• Maltose

Disaccharides

• Sucrose– A disaccharide– One D-glucose and

one D-Fructose– Connected by two anomeric carbons:

C-1 on glucose and C-2 on fructose linkages:α linkage on glucose andβ linkage on fructose

D-glucose

O

D-fructose

*

Disaccharides

• Sucrose– Anomeric C are tied-up

on both sugars

– No oxidation can occurno hemi-acetals

– Sucrose is a non-reducing sugar

– Hydrolyzed by enzymes to form a mixture ofglucose and fructose - “invert sugar”

D-glucose

O

D-fructose

*

Disaccharides

• Sucrose

α-D-glucose

O

CH2OHHO

OH

HOCH2

O

O

OHHO

HO

HOCH2

β-D-fructose

α-C-1

β-C-2

*

Disaccharides

• Lactose– A disaccharide

– One D-galactose andone D-glucose

– Connected by an β linkagebetween D-Galactose C-1 and D-Glucose C-4

– Known as an β-1,4 linkage– Found in mammalian milk

D-galactose

O

D-glucose

*

Disaccharides

O

OH

OHHO

ΟΗ

HOCH2 O

OH

OHHO

HO

HOCH2+

O

OH

OHHO

HOCH2

O

O

OHHO

ΟΗ

HOCH2

Galactose

β-D-galactose α-D-glucose

β-1,4 linkage

Lactose

Disaccharides

• Maltose– A disaccharide

– Two D-glucose monomers

– Connected by an α linkagebetween C-1 and C-4

– Known as an α-1,4 linkage (two D-glucose molecules)

– An ingredient in most syrups– “Malt sugar”

D-glucose

O

D-glucose

*

Disaccharides

O

OH

OHHO

HO

HOCH2 O

OH

OHHO

HO

HOCH2+

O

O

OHHO

HO

HOCH2

O

OH

OHHO

HOCH2Maltose

α-D-glucose α-D-glucose

α-1,4 linkage

Polysaccharides

• Starch - Amylose– Many units of α-D-glucose– Linkages are α-1,4 (same as Maltose)

– Between 1000-2000 glucoseunits (polyglucose)

– Random coils or helix

*

Polysaccharides

• Starch - Amylopectin– Also many units of α-D-glucose– Linkages are α-1,4 and α-1,6– Lots of branching– 20 to 25 glucose monomers in

the straight chain and then branching– A total of 105 to 106 glucose molecules– Use Iodine (I2) to test for starches

*

Polysaccharides

• Glycogen– Animal energy storage (about 400 g in us)

– α-D-glucose polymer– Similar to amylopectin but smaller chains– Linkages are α-1,4 and α-1,6 (branching)– 10 to 20 glucose monomers in the

straight chain and then branching– A total of 105 to 106 glucose molecules

*

Polysaccharides

• Cellulose– Linear polymer of D-glucose– Linkages are β-1,4 !– The most abundant molecule in

living tissues– Cotton is about 95% cellulose– 300 to 3000 glucose units– Form fibrous rods

*

Polysaccharides

• Cellulose– We cannot digest cellulose

• β glucose linkages!

• Many bacteria and fungihave necessary enzyme

• Ruminant mammals carrythese bacteria

• Termites also have necessarymicroorganisms

*

O

O

O

HOCH2

OH

OH

OH

OH

HOCH2

)(O O

OHOCH2

OH

OH

OH

OH

HOCH2

)

(Starch

alpha linkage Cellulose beta linkage