CARBOHYDRATES

Vocabulary flashcards covering the key terms and definitions from the lecture notes on carbohydrates (Pages 1–12).

Carbohydrates

Polyhydroxy aldehydes or polyhydroxy ketones (or compounds that yield them on hydrolysis); general formula (C(H2O))n; major short-term energy source.

Saccharide

A sugar unit; the term carbohydrate/saccharide are closely related.

Aldose

Monosaccharide that contains an aldehyde functional group.

Ketose

Monosaccharide that contains a ketone functional group.

Aldo-keto isomer

Isomerism between aldoses and ketoses; differ in the position of the carbonyl group.

-ose suffix

Suffix used to name sugars (glucose, fructose, etc.).

Glucose

Most important carbohydrate; enters glycolysis to produce ATP.

Glycogen

Storage form of glucose in animals (liver and muscle).

Glycolysis

Metabolic pathway converting glucose to pyruvate with ATP production.

Macromolecule (carbohydrate)

Large carbohydrate polymer; major long-term energy storage (starch, glycogen, cellulose).

Trioses

Three-carbon monosaccharides.

Tetroses

Four-carbon monosaccharides.

Pentoses

Five-carbon monosaccharides (e.g., ribose, xylose).

Hexoses

Six-carbon monosaccharides (e.g., glucose, galactose, fructose).

Heptoses

Seven-carbon monosaccharides.

Octoses

Eight-carbon monosaccharides.

Glyceraldehyde

Aldose triose; simplest carbohydrate used as a reference in aldose chemistry.

Dihydroxyacetone

Ketose triose; simple ketose.

Erythrose

Tetrosose (aldose).

Erythrulose

Tetrosose (ketose).

Ribose

Five-carbon aldose (pentose); component of RNA.

Xylose

Five-carbon aldose (pentose).

Ribulose

Five-carbon ketose.

Xylulose

Five-carbon ketose.

Galactose

Hexose; epimer of glucose at C4; component of lactose.

Fructose

Hexose; ketose; sweetest naturally occurring sugar.

Glucoheptose

Seven-carbon sugar (heptose).

Sedoheptulose

Seven-carbon ketose.

Fischer projection

Open-chain representation of sugars with carbon atoms as intersections; used for nomenclature.

Haworth projection

Cyclic (5- or 6-membered) ring representation of sugars; more stable than straight chain for many monosaccharides.

Straight-chain form

Open-chain (Fischer-like) form of a monosaccharide before cyclization.

Anomeric carbon

Carbonyl carbon (C1 in aldoses; C2 in ketoses) that becomes chiral on cyclization; destination of ring-opening/reclosure.

Alpha (α) form

Anomer where the OH on the anomeric carbon is on the opposite side to the CH2OH substituent in the Haworth ring.

Beta (β) form

Anomer where the OH on the anomeric carbon is on the same side as the CH2OH substituent in the Haworth ring.

Mutarotation

Interconversion between α- and β- forms of a sugar in solution, changing optical rotation.

Enantiomer

Non-superimposable mirror-image stereoisomer; same formula and connectivity, different arrangement; chiral.

Chiral

Molecule with non-superimposable mirror image; typically has at least one stereocenter.

Dextrorotatory

D; rotates plane-polarized light to the right.

Levorotatory

L; rotates plane-polarized light to the left.

D- and L- configuration

Nomenclature based on the orientation of the penultimate carbon; determines dextrorotary vs levorotary behavior.

Epimer

Diastereomer differing at exactly one chiral center.

Diastereomer

Stereoisomer not identical to its mirror image; not an enantiomer.

Optical activity

Ability of chiral molecules to rotate plane-polarized light.

Hemiacetal

Cyclic form resulting from aldehyde reacting with an alcohol during ring closure.

Hemiketal

Cyclic form resulting from ketone reacting with an alcohol during ring closure.

O-glycosidic bond

Glycosidic bond through an oxygen atom linking two sugar units; glycone + glycosyl.

N-glycosidic bond

Glycosidic bond involving a nitrogen-containing group; links certain sugars to nitrogenous bases.

Reducing sugar

Sugar with a free aldehyde or ketone group (or reactive anomeric carbon) that can reduce other compounds; gives positive Benedict’s test.

Non-reducing sugar

Sugar in which both anomeric carbons are involved in glycosidic linkage; does not reduce Benedict’s reagent.

Molisch’s test

Colorimetric test for carbohydrates detecting the presence of carbohydrates in a sample.

Furfural formation

Product of dehydration of sugars under strong acid; basis for furfural-based tests.

Seliwanoff’s test

Chemical test to distinguish aldoses from ketoses based on rate of dehydration to furfural derivatives.

Osazone

Yellow crystalline derivatives of reducing sugars formed with phenylhydrazine; used for sugar identification.

Glucosazone

Osazone derivative formed from glucose; needle-shaped crystals.

Maltosazone

Osazone derivative formed from maltose; distinctive crystal shape.

Lactosazone

Osazone derivative formed from lactose; distinctive crystal shape.

Glycosidic bond

Covalent linkage between sugar units; can be O- or N-glycosidic.

Glycone

Sugar-derived moiety in glycosidic bonds (O-glycosidic linkages).

Starch

Plant storage polysaccharide; mixture of amylose (linear) and amylopectin (branched).

Amylose

Linear polymer of D-glucose units linked by α(1→4) bonds.

Amylopectin

Branched polysaccharide with α(1→4) main chains and α(1→6) branches about every 20–30 units.

Glycogen

Animal storage polysaccharide; highly branched; similar to amylopectin but more branched.

Pectins

Polysaccharides in plant cell walls rich in galacturonic acid; contribute to gelling.

Dextrins

Short glucose polymers formed during starch digestion; intermediate products.

Agar

Polysaccharide from seaweed (galactose-based) used to culture microbes.

Glycosaminoglycans (GAGs)

Linear, sulfated or carboxylated polysaccharides; highly acidic; components of connective tissue.

Mucopolysaccharide

Repetitive disaccharide polysaccharide; often sulfated; a category within GAGs.

Chitin

Polysaccharide of N-acetylglucosamine; β(1→4) linkage; structural in exoskeletons and fungal cell walls.

Cellulose

Linear polymer of D-glucose with β(1→4) linkages; strong, form hydrogen-bonded fibers in plants.

Inulin

Fructose polymer used as a dietary fiber; also used to assess glomerular filtration in kidney testing.

Dextran

Branched glucose polymer; produced by bacteria; used as plasma volume expanders.

Chondroitin sulfate

GAG component of cartilage; sulfated disaccharide units.

Keratan sulfate

GAG found in cornea and cartilage; sulfated, with galactose and N-acetylglucosamine units.

Dermatan sulfate

GAG involved in connective tissue; sulfate-containing disaccharide units.

Hyaluronic acid

GAG found in connective tissue; large, non-sulfated; provides lubrication in joints.

Heparin

Negatively charged GAG; anticoagulant; potent inhibitor of coagulation via antithrombin.

Peptidoglycan

Major component of bacterial cell walls; polysaccharide chains cross-linked by peptides; targeted by penicillin.

Penicillin

Antibiotic that inhibits enzymes involved in peptidoglycan cross-linking, compromising bacterial cell wall integrity.

Crystal Violet

Primary stain in Gram staining; binds to peptidoglycan to classify bacteria.