Formation of Complementary Base Pairs

Click and drag the structures of the nucleotides at lower left to see which will form a complementary base pair with guanine, shown at lower right. Click on the mouse icon at left to reset.


 

Correct! The hydrogen bond donors and acceptors on guanine and cytosine match up with, or complement each other. You should draw out the structures of adenine and thymine to verify that they too complement each other.

Notice that the hydrogen bond donors and acceptors on thymine and guanine do not match each other. Perhaps you should try cytosine instead.