Biomolecules: Carbohydrates and Lipids

Vocabulary flashcards covering carbohydrates and lipids: monosaccharides, pentoses, enantiomers, polysaccharides, linkages, lipid classes, fatty acid properties, saturation, and sterols.

Sugars

Relatively small carbohydrates; simple carbohydrates.

Monosaccharides

Simple sugars that can exist in ring or linear form.

Ribose

Five-carbon sugar (pentose) found in RNA.

Deoxyribose

Five-carbon sugar lacking an oxygen at the 2' position, in DNA.

D-glucose

Enantiomer of glucose; the form commonly found in living organisms.

L-glucose

Enantiomer of glucose; rarely found in nature.

Cellulose

Polysaccharide with the least branching among plant polymers; glucose units linked by beta-1,4 glycosidic bonds.

Starch

Plant storage polysaccharide with moderate branching; glucose units linked by alpha-1,4 (and some alpha-1,6) bonds.

Glycogen

Animal storage polysaccharide; highly branched with alpha-1,4 and alpha-1,6 bonds.

Beta-1,4 glycosidic linkages

Bond between glucose units in cellulose.

Alpha-1,4 glycosidic linkages

Bond between glucose units in starch and glycogen.

Alpha-1,6 glycosidic linkages

Branch points in starch and glycogen.

Branched polysaccharides and solubility

More branching leads to greater solubility.

Lipids

One of four major lipid classes: Waxes, Steroids, Triglycerides, and Phospholipids.

Waxes

Esters of long-chain fatty acids with long-chain alcohols; hydrophobic.

Steroids

Lipids built from four fused rings; includes sterols; some have a single hydroxyl group (sterols).

Triglycerides

Energy storage lipids formed by glycerol esterified to three fatty acids.

Phospholipids

Main membrane lipids with two fatty acids and a phosphate-containing head group.

Fatty acid length

In cells, common fatty acid chain lengths are 16 or 18 carbons.

Double bonds in fatty acids

Presence of C=C double bonds creates unsaturation.

Essential fatty acids

Unsaturated fatty acids that cannot be synthesized by the organism.

Saturated fats

Fats with no double bonds; typically derived from animals.

Unsaturated fats

Fats containing one or more double bonds; more common in plants.

Sterol

Steroids with only one hydroxyl group.

Wax ester structure

Wax: fatty acid linked by an ester bond to a long-chain alcohol.