Final answer:
DNA is made up of two anti-parallel strands twisted around each other. Adenine pairs with thymine and cytosine pairs with guanine.
Step-by-step explanation:
DNA is made up of two strands that are twisted around each other to form a helix. Adenine pairs up with thymine and cytosine pairs with guanine.
The two strands are anti-parallel in nature; that is, the 3' end of one strand faces the 5' end of the other strand. Only sugar contributes to the DNA structure.