BICH 440

D- glyceraldehyde

L-Glyceraldehyde

D-Ribose

D-Glucose

D-Mannose

D-Galactose

Dihydroxyacetone

D-Ribulose

D-Fructose

Enantiomers

Stereoisomers that are mirror images of each other

Diasteromers

stereoisomers that are not mirror images of each other

Epimers

diastereomers that differ around one carbon

Glucose can cyclize to form a cyclic hemiacetal

Fructose can cyclize to form a cyclic hemiketal

The dominant cyclic form of glucose is a

pyranose (six membered ring)

The dominant cyclic form of fructose is a

furanose (five membered ring)

Cyclization results in a new stereocenter called the

anomeric carbon

Monosaccharides that differ in configuration only at their anomeric carbons

Anomers

Anomers can interconvert

mutarotation

a-D-glucopyranose Haworth Projection

B-D-Glucopyranose

is it the boat or the chair conformation where hexoses exit in?

chair conformation

carbohydrates with a free anomeric carbon

Reducing sugars

What can convert a reducing sugar into a sugar acid

Oxidants such as peroxide, ferricyanide and some metals

Reduced form of monosaccharides where all carbons have a hydroxyl group

Sugar alcohols

Fundamental constituents of DNA, and RNA

Deoxy sugars

Phosphate esters like ATP

Sugar esters

One or more amino groups substituted for a hydroxyl

Amino sugars

Basis for polysaccharides

Acetals, ketals, and glycosides

Monosaccharides can be linked via the

anomeric carbon and an alcohol substituent

Derived from furanoses

furanosides

those from pyranoses

pyranosides

Formed between the anomeric carbon to the OR group of the attached monosaccharide

glycosidic bond

Lactose

Sucrose

Cellulose

Chitin

a-Amylose

Formation of a Glycosidic linkage is fundementally a

condensation, or removal of an H2O

Very slow under physiologcial conditions and catalyzed by enzymes

Hydrolysis

Lactose is hydrolyzed to the component monosaccharides by an enzyme called

B-D-galactosidase or lactase

Sucrose is the main product of

photosynthesis

What is sucrose used to produce?

cellulose and starch

Main storage polysaccharide for glucose, the primary fuel for generating metabolic energy

Glycogen

— The principle energy source in plants and comes in two types

Starch, a-amylose & amylopectin

Amylose is a linear polymer with an helical strucutre

Amylopectin is a branched polymer formed from amylose connected via a1-6 linkages

Glycogen vs amylopectin, which has more frequent branching?

Glycogen

Homopolymer of glucose with B(1→4) linkages

cellulose

What is cellulose a primary component of?

Plant cell walls

What polymers are parallel

homopolymers

Hydrogen bonding that generates sheets of cellulose polymers

Interpolymer

Principle structural component of exoskeletons of invertebrates and present in most fungi and algae

Chitin

Homopolymer of B(1→4) linked N-acetyl-D-glucosamine residues

Chitin

Almost all membrane and extracellular proteins of eukaryotes are

glycosylated

Oligosaccharides are covalently attached by either

N- or O-glycosidic bonds

N-linked glycosylation occurs cotranslationally

while exiting the ribosome

N-linked glycosylation occurs on Asn via a

b-linkage

O-linked glycosylation occurs primarly in the

Golgi

O-linked glycosylation occurs on

Ser or Thr

Carbohydrates

CnH2nOn

oligo- also means

few

poly- also means

many

What is essential to metabolism

Monosaccharides

For adoses, the carbon with the aldehyde group CHO is designated as

carbon one

For ketoses, the carbon with the ketone group (C=O) is assigned the

lowest possible number

Reducing sugars

carbohydrates with a free anomeric carbon

Sugar alcohols

Reduced form of monosaccharides where all carbons have a hydroxyl group

What does lactase do?

Hydrolyzes lactose