Read It Backwards, Get a Different Molecule

You'll learnwhy a polymer's two different ends give it direction, so reversing the sequence makes a different molecule.

A biological polymer has two chemically different ends, so it runs one way and one way only: proteins from N to C, nucleic acids 5′ to 3′. Reverse the order and you have written a different molecule — and the same trap waits one level down, in sugars and fats that share a formula and do opposite jobs. Twelve short steps; press Next for each one.

12 STEPS · 6 QUICK CHECKS · PROTEINS N→C · NUCLEIC ACIDS 5′→3′ · SAME FORMULA ≠ SAME MOLECULE · v6

two different ends · one reading direction · arrangement is identity

Before you start

What you're looking at

A short peptide of four amino-acid chevrons linked head to tail, a free amino end at left, a free carboxyl end at right.

The question

Because the two ends differ, which way does the chain read — and what happens if you reverse it?

Step 1 / 12