Carbohydrates

cellulose, sugars, starch

provide energy through oxidation; supply carbon for synthesis of cell components; store chemical energy; form parts of cell and tissue structures

hydroxy- aldehydes/ketones (aka, polyhodroxy aldehydes and polyhydroxy ketones)

single polyhydroxy aldehyde/ ketone unit

two monosaccharide units linked together by the acetal or ketal linkages

3-10 monosaccharide units (less common)

very large chain of linked monosaccharide units; polymer consisting entirely of D-glucose units

glucose, fructose, galactose

at the top, H-C=O. at the bottom, CH2OH. Differences are in carbons rungs in between.

D-glyceraldehyde.

tetrahedral

each of a pair of molecules that are mirror images of each other.

a carbon atom with four different groups attached

when two compounds have the same molecular and structural formulas but cannot be superimposed on each other

R1 | C=O | R2

at or near the top

the oxygen of the carbonyl group at the top will point to the side which goes above.

The intersection of two lines

a prefix label of: L- or "levo" meaning "left" and D- or "dextro" meaning "right" (for example: D-glucose and L-glucose)

the "L-" and "D-" label applies to the side of the molecule which contains the -OH farthest from the first chiral carbon.

trioses, tetroses, pentoses, and hexoses (note, sugars have the "-ose" suffix)

aldehydes in a sugar contain prefix "aldo-" ketones in a sugar contain prefix "keto-" (for example: glucose, a six carbon sugar which contains an R-CHO, or aldehyde, group, is an "aldohexose"; ribulose, a five carbon sugar contains an R1-C=O R2, a ketone, is a "ketopentose")

most monosaccharides are aldoses. most monosaccharides belong to the D- series.

monosaccharides are extremely soluble in water; this is because of the multiple -OH groups; it is important in living organisms because their solubility allows them to be transported rapidly in the circulatory system.

hemiacetals and hemiketals

OR | R-- C --OH | R

carbon 5 adds to the aldehyde group of carbon 1; predominantly cyclic hemiacetals/hemiketals

a "Pyranose" (pi-ran-ose) ring (a cyclic hemiacetal or hemiketal)

only the Carbons at positions 1 and 5 change, the rest of the molecule is simply along for the ride.

beginning with a properly drawn monosaccharide chain... 1. draw the ring with its oxygen to the back 2. put the anomeric carbon (C-1) on the right side 3. the terminal -CH2OH group (C-6) is always shown above the ring for D-monosaccharides

"α-" means that the -OH on C-1 of the ring is positioned below the ring, and a "β-" means that the -OH on C-1 of the ring is positioned above the ring.

Furanose ring

D-fructose

the "anomeric" carbon

a carbonyl adjacent to an ether linkage. General formula: R-C=O | OR

test to indicate reducing sugars. reduces all monosaccharides and some disaccharides.

aldehydes and ketones having adjacent -OH groups are readily oxidized; open chain and cyclic forms of monosaccharides are readily oxidized

acetals and ketals

a glycoside is an acetal or ketal formed from the reaction of cyclic monosaccharides with alcohols in the presence of acid

hemiacetal sugar + alcohol ---> acetal ring + H2O

when two monosaccharide rings are bonded using a C-O-C bond

differs in the orientation of -OH group attached to C-4

hydrolysis of disaccharides yields monosaccharide units

Disaccharide two glucose units joined by a glycoside (C-O-C) linkage between C-1 on the first glucose and C-4 on the second unit; has an "α-" gylcosidic linkage between glucose units (linkage points below).

Disaccharide composed of one molecule of D-galactose and one of D-glucose; linkage between units is "β-" (1--->4)

Disaccharide common sugar; composed of glucose and fructose joined by an "α-" linkage from C-1 of glucose and a "β-" linkage from C-2 of fructose

polysaccharide

deep blue

amylose and amylopectin

long unbraced chain of D-glucose units connected by an "α-" (1--->4) linkages

animal starch; similar to amylopectin

the most important polysaccharide and most abundant compound in nature; provides rigidity and strength to plant cell walls; consists of D-glucose units linked by "β-" (1-->4) linkage

genetic disease (autosomal recessive) in which an enzyme needed to metabolize galactose is deficient or absent; typically develops shortly after birth

Congenital disorder consisting of an inability to digest milk and milk products; absence or deficiency of lactase results in an inability to hydrolyse lactose