3 Carbohydrates and Lipids

alpha-helix structure

type of secondary protein structure formed by folding the polypeptide into a helix shape with hydrogen bonds stabilizing the structure

amino acid

a protein's monomer; has a central carbon or alpha carbon to which an amino group, a carboxyl group, a hydrogen, and an R group or side chain is attached; the R group is different for all 20 common amino acids

beta-pleated sheet

secondary structure in proteins in which hydrogen bonding forms “pleats” between atoms on the polypeptide chain's backbone

Biological macromolecule

Large molecule necessary for life that is built from smaller organic molecules.

Carbohydrate

Biological macromolecule with a carbon to hydrogen to oxygen ratio of 1:2:1; serves as energy sources and structural support in cells.

Cellulose

Polysaccharide that comprises the plant cell wall; provides structural support to the cell.

Chitin

Type of carbohydrate that forms the outer skeleton of arthropods and fungi cell walls.

Dehydration synthesis

Reaction that links monomer molecules, releasing a water molecule for each bond formed.

Disaccharide

Two sugar monomers linked by a glycosidic bond.

Glycogen

Storage carbohydrate in animals.

Glycosidic bond

Bond formed by a dehydration reaction between two monosaccharides, eliminating a water molecule.

Hydrolysis

Reaction that breaks down larger molecules into smaller molecules using water.

Lipid

Macromolecule that is nonpolar and insoluble in water.

Monomer

Smallest unit of larger molecules that are polymers.

Monosaccharide

Single unit or monomer of carbohydrates.

Phospholipid

Major constituent of membranes; comprised of two fatty acids and a phosphate-containing group attached to a glycerol backbone.

Polymer

Chain of monomer residues linked by covalent bonds; polymerization is the process of forming polymers from monomers by condensation.

Polysaccharide

Long chain of monosaccharides; may be branched or unbranched.

Saturated fatty acid

Long-chain hydrocarbon with single covalent bonds; maximizes hydrogen atoms attached to the carbon skeleton.

Starch

Storage carbohydrate in plants.

Steroid

Type of lipid comprised of four fused hydrocarbon rings forming a planar structure.

Trans fat

Fat formed artificially by hydrogenating oils, altering the arrangement of double bonds compared to naturally occurring lipids.

Triacylglycerol (triglyceride)

Fat molecule consisting of three fatty acids linked to a glycerol molecule.

Unsaturated fatty acid

Long-chain hydrocarbon with one or more double bonds in the hydrocarbon chain.

Wax

Lipid made of a long-chain fatty acid esterified to a long-chain alcohol; serves as a protective coating on feathers, fur, and leaves.