Carbohydrates and Lipids – Key Vocabulary

A comprehensive set of vocabulary flashcards covering the structures, functions, and key terms related to carbohydrates and lipids, as discussed in the lecture notes.

Carbohydrate

Carbon-based molecule with formula (CH2O)n; functions in cell structure, identity, and energy storage.

Monosaccharide

Single sugar unit that serves as a monomer for larger carbohydrates.

Oligosaccharide

Short carbohydrate polymer composed of a few monosaccharides.

Polysaccharide

Large carbohydrate polymer made of many monosaccharide monomers.

(CH2O)n

General chemical formula for most carbohydrates; n indicates number of carbon-hydrate groups.

Carbonyl group

Functional group (C=O) whose position distinguishes aldoses (end) from ketoses (middle).

Hydroxyl group

-OH functional group that participates in glycosidic bond formation and hydrogen bonding.

Aldose

Monosaccharide with the carbonyl group at the end of the carbon chain.

Ketose

Monosaccharide with the carbonyl group within the carbon chain.

Triose

Monosaccharide containing three carbon atoms.

Pentose

Monosaccharide containing five carbon atoms.

Hexose

Monosaccharide containing six carbon atoms.

Ring form

Cyclic structure adopted by most sugars in aqueous solution.

Disaccharide

Carbohydrate formed when two monosaccharides are linked by a glycosidic bond.

Condensation reaction

Reaction in which two molecules join, producing water; forms glycosidic bonds in carbohydrates.

Hydrolysis reaction

Reaction that breaks covalent bonds by adding water; splits glycosidic linkages.

Glycosidic linkage

Covalent bond formed between two sugars via condensation of hydroxyl groups.

α-1,4-glycosidic linkage

Bond connecting C-1 of one α-glucose to C-4 of another; common in starch and glycogen.

β-1,4-glycosidic linkage

Bond connecting C-1 of one β-sugar to C-4 of another; found in cellulose, chitin, peptidoglycan.

Starch

Plant storage polysaccharide composed of amylose (unbranched) and amylopectin (branched).

Amylose

Unbranched component of starch with α-1,4 linkages forming a helix.

Amylopectin

Branched component of starch containing occasional α-1,6 linkages.

Glycogen

Highly branched animal storage polysaccharide with many α-1,6 linkages.

Cellulose

Structural polysaccharide of plant cell walls composed of β-1,4-linked glucose strands hydrogen-bonded in parallel.

Chitin

Structural polysaccharide of fungal cell walls and arthropod exoskeletons made of β-1,4-linked N-acetylglucosamine.

Peptidoglycan

Bacterial cell-wall polysaccharide of alternating N-acetylmuramic acid and N-acetylglucosamine cross-linked by peptides.

N-acetylglucosamine (NAG)

Modified monosaccharide forming part of chitin and peptidoglycan.

N-acetylmuramic acid (NAM)

Modified monosaccharide unique to peptidoglycan that carries a peptide chain.

Amino group

-NH2 functional group that acts as a base by accepting a proton.

Carboxyl group

-COOH functional group that acts as an acid by donating a proton.

Phosphate group

-PO4 functional group storing large amounts of chemical energy when linked together.

Sulfhydryl group

-SH functional group that can form disulfide bonds in proteins.

Lipid

Carbon-containing compound that is largely nonpolar and insoluble in water.

Hydrocarbon

Molecule consisting only of carbon and hydrogen; nonpolar and hydrophobic.

Isoprenoid

Branched hydrocarbon built from isoprene units; functions as pigments, vitamins, and lipid precursors.

Fatty acid

Unbranched hydrocarbon chain (14–20 C) with terminal carboxyl group.

Saturated fatty acid

Fatty acid with only single C–C bonds; straight chain packs tightly.

Unsaturated fatty acid

Fatty acid containing one or more C=C double bonds, creating kinks in the chain.

Polyunsaturated fatty acid

Fatty acid with multiple double bonds in its hydrocarbon chain.

Steroid

Lipid family characterized by a bulky four-ring structure; includes cholesterol and sex hormones.

Cholesterol

Steroid component of animal plasma membranes that modulates fluidity.

Fat (Triacylglycerol)

Lipid consisting of three fatty acids linked to glycerol; primary energy storage molecule.

Glycerol

Three-carbon alcohol that forms the backbone of fats and phospholipids.

Ester linkage

Bond joining glycerol’s hydroxyl to a fatty acid’s carboxyl group in fats and phospholipids.

Phospholipid

Lipid with glycerol bonded to a phosphate group and two hydrophobic tails; main component of cell membranes.

Hydrophilic head

Polar, water-loving region of a phospholipid composed of glycerol, phosphate, and charged group.

Hydrophobic tail

Nonpolar fatty acid or isoprenoid chains of a phospholipid that avoid water.

Plasma membrane

Selective barrier formed by a phospholipid bilayer that separates the cell from its environment.

Selective barrier

Property of membranes that allows entry of needed substances while excluding harmful ones.

Energy storage (in lipids)

Function of fats which contain numerous high-energy C–C and C–H bonds, storing roughly twice the energy of carbohydrates.