Link paperclips end to end and a short clip becomes a long chain with new strength and flexibility. Polymers are molecules built by joining thousands of small units this way — the trick behind plastic bottles, nylon, and even DNA.
Repeating units, chained together
A polymer is a large molecule built from many small repeating units called monomers, joined in a chain. Polymerization links monomers together — often by addition (unsaturated monomers add across double bonds) or condensation (units join while releasing a small molecule like water).
Polyethylene (plastic bags) and nylon are synthetic polymers; proteins (from amino acids), starch, and DNA are natural biopolymers. The same principle — repeating monomers — spans both.
Ethylene monomers (CH₂=CH₂) add together into polyethylene, —CH₂—CH₂—CH₂— repeated thousands of times.
- A protein is a long chain of repeating units.
- Recall what those units are called in general and in proteins.
- State the monomer of a protein.
What you should see: The repeating units of any polymer are monomers; for proteins, the monomers are amino acids.