When we consider the orientations of the two strands of DNA that make up a double helix, we see that they are:
A. parallel.
B. antiparallel.
C. mirror images.
Answer:
B. antiparallel.
Step-by-step explanation:
A single DNA strand has two distinct ends. These are the 3' and 5' ends. At the 3' end, the 3' OH of the pentose sugar is present freely and is not involved in phosphodiester bond. The 5' end of DNA has a free phosphate group. A DNA double helix has two DNA strands. These two DNA strands of a double helix are anti-parallel in nature. This means that the 3' end of one DNA strand is present opposite to the 5' end of another DNA strand.