Answer: option E) All of these choices are correct.
Explanation:
The strands in a double helix of DNA are:
- wound around each other with 10 base pairs per turn.
According to Watson-crick model, DNA molecule consists of TWO chains wound around each other at right angles to form a DOUBLE HELIX with 10base pairs per turn.
- held together via hydrogen bonds.
Hydrogen bonds hold together the pairs of bases, as Adenine pairs with thymine by 2 hydrogen bonds, and cytosine pairs with guanine by 3 hydrogen bonds.
- complementary.
The double helix is specific as pairing ALWAYS occurs between Adenine and thymine, and between Cytosine and Guanine. thus it is complementary.
- antiparallel.
DNA strands DO NOT run in the same direction, thus they are antiparallel. i.e one strand runs in 5' - 3' direction, and the other run 3' - 5' direction, so one strand ascends while the other descends.
So, all of these choices are correct.
