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
Aldohexoses
aldehyde function
six carbons
carbohydrates
or
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
CHO
CHO
CHO
HO
H
H
OH
H
HO
H
H
OH
HO
CH 2OH
A
CH 2OH
B
CHO
OH
H
CH 2OH
C
HO
H
H
OH
CH 2OH
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:
triose
tetrose
The ketone is located
on carbon #2
pentoses
Penultimate is the next
To last carbon
hexoses
*
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
•Aldose
-D-glucose
-The most important
monosaccharide
-White solid
-Formula C6H12O6
- Sugar used in our
bodies
•
Ketose
– D-Fructose
– Known as “fruit sugar”
– Found combined with
glucose
in the disaccharide
sucrose
CH 2OH
O
H
1
C
H
HO
H
H
2
C
3
C
4
C
O
OH
H
OH
HO
OH
OH
OH
CH 2OH
CH 2 OH
D-fructose
5
C
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
*
D-glucose
– A disaccharide
O
– One D-glucose and
D-fructose
one D-Fructose
– Connected by two anomeric carbons:
C-1 on glucose and C-2 on fructose
linkages:
 linkage on glucose and
 linkage on fructose
Disaccharides
*
• Sucrose
D-glucose
– Anomeric C are tied-up
O
on both sugars
D-fructose
– No oxidation can occur
no hemi-acetals
– Sucrose is a
non-reducing sugar
– Hydrolyzed by enzymes to form a mixture of
glucose and fructose - “invert sugar”
Disaccharides
• Sucrose
*
HO
O
HOCH2
HO
-D-glucose
OH
-C-1
O
O
HOCH2
-C-2
HO
CH2 OH
OH
-D-fructose
Disaccharides
• Lactose
*
– A disaccharide
D-galactose
O
– One D-galactose and
one D-glucose
– Connected by an  linkage
between D-Galactose C-1 and D-Glucose C-4
– Known as an -1,4 linkage
– Found in mammalian milk
D-glucose
Disaccharides

HO
O
HOCH2
HO
+
OH
-D-galactose
O
HOCH2
HO
OH
OH
-D-glucose
OH

HOCH2
HO
O
-1,4 linkage
OH
O
Galactose
Lactose
HOCH2
HO
O
OH
OH
Disaccharides
• Maltose
*
– A disaccharide
D-glucose
O
D-glucose
– Two D-glucose monomers
– Connected by an  linkage
between C-1 and C-4
– Known as an -1,4 linkage (two D-glucose molecules)
– An ingredient in most syrups
– “Malt sugar”
Disaccharides
HO
HO
HOCH2
+
O
HO
-D-glucose
HOCH2
OH
O
HO
OH
-D-glucose
OH
OH
HO
HOCH2
O
HO
OH
-1,4 linkage
Maltose
O
HOCH2
HO
O
OH
OH
Polysaccharides
• Starch - Amylose
*
– Many units of -D-glucose
– Linkages are -1,4 (same as Maltose)
– Between 1000-2000 glucose
units (polyglucose)
– Random coils or helix
Polysaccharides
• Starch - Amylopectin
*
– Also many units of -D-glucose
– Linkages are -1,4 and -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)
– -D-glucose polymer
– Similar to amylopectin but smaller chains
– Linkages are -1,4 and -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 -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
•  glucose linkages!
• Many bacteria and fungi
have necessary enzyme
• Ruminant mammals carry
these bacteria
• Termites also have necessary
microorganisms
HOCH2
HOCH2
HOCH2
(
O
OH
Starch
O
OH
O
OH
O
OH
HOCH2
)
OH
alpha linkage
(
O
OH
Cellulose OH
O
)
OH
beta linkage