Fill in all the gaps, then press "Check" to check your answers. Use the "Hint" button to get a free letter if an answer is giving you trouble. You can also click on the "[?]" button to get a clue. Note that you will lose points if you ask for hints or clues!

(North American), Crick
(British) and (New Zealander)
were the discoverers of the molecular
structure of DNA, the double made
of two chains paired by
their -containing bases. They
won the Nobel prize in Medicine in 1962
for the discovery.