Polysaccharides and Glycobiology

A set of 21 vocabulary flashcards reviewing essential terms on polysaccharides, glycoconjugates, and their biological roles.

O-Glycosidic Bond

covalent linkage joining two monosaccharides. formed when a hydroxyl group of one sugar reacts with the anomeric carbon of another, excluding water.

Reducing End

The end of a sugar that has a free anomeric carbon capable of acting as a reducing agent. formation of a bond renders the sugar non-reducing

Homopolysaccharide

A polysaccharide with only one sugar species; serves in storage (starch, glycogen) or structure (cellulose, chitin).

Heteropolysaccharide

A polysaccharide with 2+ different monosaccharides; provides extracellular support (e.g., hyaluronic acid, heparin).

Amylose

long, unbranched component of starch made of D-glucose units connected by α(1→4) linkages.

Amylopectin

The larger, branched component of starch with α(1→4) glucose chains and highly branched α(1→6) linkages

Glycogen

A highly branched glucose polymer with α(1→4) main chains and α(1→6) branches; more compact and branched than starch.

Cellulose

A linear, unbranched β(1→4) D-glucose homopolysaccharide; tough, fibrous, water-insoluble substance that is indigestible by most animals (except ruminants) because they lack the cellulase enzyme

Chitin

A linear β(1→4) polymer of N-acetylglucosamine; digestible and more hydrophobic than cellulose; found in exoskeletons of insects, crustaceans, and fungi

Heparan Sulfate

A heteropolysaccharide with variable, non-random arrangements of sulfated and non-sulfated sugars. sulfated residues allow it to interact with positive regions of proteins

Glycoprotein

A protein covalently linked to one or more oligosaccharides; located on cell surfaces, ECM, blood, and organelles; information-rich and heterogenous

Glycosaminoglycan (GAG)

A sulfated heteropolysaccharide in the ECM that provides viscosity, adhesiveness, and tensile strength.

Proteoglycan

A macromolecule consisting of one or more sulfated GAG chains covalently attached to a membrane or secreted protein.

Glycolipid

A plasma-membrane lipid whose hydrophilic head is an oligosaccharide; mediates cell-cell interactions (ABO blood group determination)

Glycosphingolipid

A sphingosine-containing glycolipid abundant in neurons, participating in signal transduction.

Sugar Code

The concept that the vast structural variability of oligosaccharides encodes specific biological information through branching and stereochemistry.

Lectin

A carbohydrate-binding protein or glycoprotein that binds with high specificity and affinity; useful in cell recognition + immune response

Hemagglutinin

An influenza virus lectin that binds terminal sialic acid on host glycoproteins/glycolipids, facilitating viral entry.

Neuraminidase

An influenza viral glycoprotein that cleaves sialic acid to release new virions; its activity is blocked by the drug Tamiflu.

extracellular matrix (ECM)

holds cells together + provides porous pathway for nutrient and oxygen diffusion. composed of interlocking meshwork of heteropolysaccharides and fibrous proteins

antithrombin

only binds to and inhibits thrombin in the presence of heparan sulfate or heparin (from mast cells)

naming oligosaccharides

1. nonreducing end on left; name configuration (a or b) at anomeric carbon joining first unit to second

2. name nonreducing residue with “furano” (5C) or “pyrano” (6C)

3. use parentheses to indicate the two carbons joined by the bond with an arrow (1→4)

4. name second residue and repeat