These macromolecules are polar [polar: having different ends] because they are formed by head to tail condensation of polar monomers. Let's look at the three major classes of macromolecules to see how this works, and let's begin with carbohydrates.
Bostwick Steel Lath Company advertisement for steel truss loop type metal lath in 1920. A lath or slat is a thin, narrow strip of straight-grained wood used under roof shingles or tiles, on lath and plaster walls and ceilings to hold plaster, and in lattice and trellis work.
Metallurgy. a designation of a given fineness of powder used in powder metallurgy in terms of the number of the finest screen through which almost all the particles will pass: This powder is 200 mesh. to catch or entangle in or as if in a net; enmesh. to form with meshes, as a net. Machinery. to engage, as gear teeth.