Question

What do you understand by the antiparallel arrangement of DNA strands?

Answer 1

Hint:DNA or Deoxyribonucleic acid is the hereditary material that contains a unique genetic code. It is made up of two long polynucleotides that wind around one another to form a shape known as a double helix.

Complete answer:
Antiparallel means parallel but oppositely directed. The two DNA chains are antiparallel,i.e., they run parallel but in opposite directions. 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 phosphate groups at the start of two DNA strands (poles) are in the opposite positions.
Both strands of DNA double helix can grow in 5' to 3' direction, but they grow in opposite directions due to the opposite orientation of the sugar molecule in them. One chain has a 5' - 3' direction while the other chain has a 3'-5' direction. The antiparallel orientation allows for the base pairs to compliment one another. Antiparallel DNA is also more structurally stable than parallel DNA.
The advantage of the antiparallel orientation of DNA is that it helps in DNA replication, as the replication fork one strand allows steady replication, thereby known as leading strand while the other becomes lagging strand. Antiparallel DNA is also more structurally stable than parallel DNA.

Note: It is to be noted that DNA is made up of nucleotides. The nucleotide has two components: a backbone, made from the sugar deoxyribose and phosphate groups, and nitrogenous bases, known as cytosine, thymine, adenine, and guanine.