Carbohydrate: Structure and Type of Biological Importance

Vocabulary flashcards covering monosaccharides, disaccharides, oligosaccharides, polysaccharides, glycosaminoglycans, and their clinical/biological significances.

Carbohydrates

Organic compounds composed of carbon, hydrogen, and oxygen that serve as the most abundant biomolecules in nature.

Monosaccharides

The simplest form of carbohydrates, typically consisting of 3-9 carbon atoms, which cannot be hydrolyzed into smaller units.

Aldose

A monosaccharide that contains an aldehyde functional group ($\text{R-CHO}$).

Ketose

A monosaccharide that contains a ketone functional group ($\text{R-CO-R'}$).

Disaccharides

Carbohydrate molecules composed of two monosaccharide units linked together by glycosidic bonds.

Oligosaccharides

Carbohydrates consisting of short chains of 3 to 10 monosaccharide units joined by glycosidic bonds.

Polysaccharides

Carbohydrates containing long chains of more than 10 monosaccharide units, which can be linear or branched.

Glycosidic Bond

The carbon-oxygen covalent bond (or "oxygen bridge") formed between monosaccharides in a dehydration reaction.

D-Glucose

The most common monosaccharide in biological systems, central to cellular respiration, stored as glycogen, and also known as dextrose or blood sugar.

Pyranose Form

The cyclic six-membered ring structure of glucose, which makes up more than 99% of glucose in solution.

Isomers

Compounds sharing the exact same molecular formula but different structural arrangements, such as glucose, galactose, and fructose ($C_6H_{12}O_6$).

D-Ribose

A pentose sugar that forms a structural component of nucleic acids and coenzymes such as ATP, NAD(P), and flavin coenzymes.

L-Xylulose

A pentose metabolic intermediate that is excreted in the urine in essential pentosuria.

D-Fructose

A hexose sugar found in fruit juices and honey; its accumulation due to hereditary fructose intolerance leads to hypoglycemia.

D-Galactose

A hexose sugar obtained from lactose hydrolysis and synthesized in the mammary gland for milk lactose; failure to metabolize it in hereditary galactosemia leads to cataracts.

Sucrose

A non-reducing disaccharide (table sugar) composed of an $\alpha\text{-D-glucose}$ unit and a $\beta\text{-D-fructose}$ unit linked by an $\alpha,\beta(1 \rightarrow 2)$ glycosidic bond.

Lactose

A reducing disaccharide (milk sugar) made of a $\beta\text{-D-galactose}$ unit and a $\text{D-glucose}$ unit joined by a $\beta(1 \rightarrow 4)$ glycosidic bond.

Maltose

A reducing disaccharide (malt sugar) composed of two $\text{D-glucose}$ units joined by an $\alpha(1 \rightarrow 4)$ glycosidic bond.

Raffinose

An oligosaccharide composed of galactose, glucose, and fructose found in beans, cabbage, Brussels sprouts, and whole grains.

Stachyose

An oligosaccharide composed of two galactose units, one glucose unit, and one fructose unit found in soybeans, lentils, and beans.

Fructo-oligosaccharides (FOS)

Short chains of fructose units that act as prebiotics to promote the growth of beneficial gut bacteria such as bifidobacteria.

Galacto-oligosaccharides (GOS)

Prebiotic oligosaccharides composed of several galactose units plus glucose, added to infant formula to support digestive health.

Mannan-oligosaccharides (MOS)

Oligosaccharides composed of mannose units derived from yeast cell walls and mushrooms that support immune function and prevent harmful bacterial attachment in the gut.

Inulin

Fructose unit chains that act as prebiotics to promote gut health and assist in regulating blood sugar and cholesterol levels.

Starch

A plant storage polysaccharide consisting of linear amylose and branched amylopectin chains of glucose.

Glycogen

A highly branched glucose storage polysaccharide stored in human liver and muscle tissues to supply energy during fasting and exercise.

Cellulose

A plant cell wall structural polysaccharide composed of long, linear chains of glucose joined by $\beta\text{-}1,4$ glycosidic bonds that serves as indigestible dietary fiber.

Chitin

A structural polysaccharide made of N-acetylglucosamine chains found in crustacean exoskeletons that exhibits antimicrobial properties.

Hemicellulose

A heterogeneous group of insoluble fiber polysaccharides found in plant cell walls that promotes healthy digestion and prevents constipation.

Agar

A polysaccharide composed of galactose units extracted from red algae (seaweed) used as a laxative and gelling agent.

Glycosaminoglycans (GAGs)

Long, unbranched polysaccharides made of repeating disaccharide units containing an amino sugar (like N-acetylglucosamine or N-acetylgalactosamine).

Hyaluronic Acid

A glycosaminoglycan found in connective tissues, synovial fluid, and skin that functions in joint lubrication and wound healing.

Heparin and Heparan Sulfate

Potent anticoagulant glycosaminoglycans used in clinical settings to prevent blood clotting.

Chondroitin Sulfate

A glycosaminoglycan found in cartilage and animal connective tissues used in dietary supplements for osteoarthritis treatment.

Dermatan Sulfate

A glycosaminoglycan found in skin, blood vessels, and heart valves involved in tissue repair, cell proliferation, structural integrity, and natural anticoagulation.