Anti-parallel strands of a DNA molecule mean that phosphate groups at the start of two DNA strands (poles) are in opposite position. DNA (Deoxyribonucleic Acid) is composed of two polynucleotide strands (the polymers of nucleotides), which looks like a ladder. The two polynucleotide strands run ‘antiparallel’ to each other, with nitrogenous bases projecting inwards. The term ‘antiparallel’ means that the strands run in opposite directions, parallel to one another. Each DNA molecule has two strands of nucleotides Each strand has a sugar-phosphate backbone, but the orientation of the sugar molecule is opposite in the two strands. The antiparallel orientation allows for the base pairs to compliment one another. Antiparallel DNA is also more structurally stable than parallel DNA.