Carbohydrate Structure Review - Key Terms (Video)

Vocabulary flashcards covering key concepts from the carbohydrate lecture notes: aldose/ketose, D/L, Fischer and Haworth representations, anomers, ring forms (pyranose/furanose), cyclization, and equilibrium considerations.

Aldose

A monosaccharide with an aldehyde group (CHO) at the carbonyl in the linear form; C1 is the aldehyde, cyclizes to form a hemiacetal.

Ketose

A monosaccharide with a ketone group (C=O) in the linear form (typically at C2); cyclizes to form a hemiketal.

D-configuration

Relative configuration determined at the chiral center furthest from the carbonyl (penultimate carbon in aldoses); OH on the right in the Fischer projection indicates D.

L-configuration

Mirror configuration to D; OH on the furthest chiral center is on the left in the Fischer projection.

Fischer projection

A linear representation of sugars showing stereochemistry: vertical chain with carbonyl at the top and horizontal substituents projecting out.

Hexose

A monosaccharide with six carbon atoms (C6); e.g., glucose, galactose, mannose.

Anomeric carbon

The carbon that becomes a stereocenter during cyclization; C1 in aldoses and C2 in ketoses.

Anomer

Cyclic stereoisomers of a sugar that differ at the anomeric carbon (alpha vs beta) after cyclization.

Alpha anomer

Anomer where the OH on the anomeric carbon is on the opposite side (trans) to the CH2OH substituent; in Haworth projection often down.

Beta anomer

Anomer where the OH on the anomeric carbon is on the same side (cis) as the CH2OH substituent; in Haworth projection often up.

Haworth projection

Cyclic representation of a sugar showing a ring and substituents above/below the plane; used to depict alpha/beta and relative stereochemistry.

Hayworth projection

Alternative spelling used in notes for Haworth projection (same concept).

Hemialetal (hemiacetal)

Cyclic product formed when an aldehyde reacts with a distal hydroxyl group to form a new C–O–C–O center and a new stereocenter.

Hemiketal

Cyclic product formed when a ketone reacts with a distal hydroxyl group to form a new C–O–C–O center and a new stereocenter.

Cyclization

Intramolecular reaction where a carbonyl carbon reacts with a distant hydroxyl to form a cyclic hemiacetal or hemiketal; ring size depends on which hydroxyl attacks.

Pyranose

Six-membered ring form of a sugar (five carbons + one oxygen) commonly formed by hexoses.

Furanose

Five-membered ring form of a sugar (four carbons + one oxygen) formed by some sugars.

Open-chain to cyclic interconversion

Interconversion between the linear (open-chain) form and the cyclic (ring) form of a sugar via cyclization; the cyclic form is usually predominant.

Equilibrium constant (K_eq) for cyclization

K_eq = [cyclized form] / [linear form] for the reversible cyclization; values >1 favor the cyclic form.

Le Chatelier's principle (in sugar cyclization context)

If a component (e.g., linear form) is removed or added, the system shifts to re-establish equilibrium by converting more of one form to the other.

Mutarotation

Interconversion between alpha and beta anomers of a sugar through the open-chain form in solution.