26.According to DNA double helix, the two strands of polynucleotides: A. Are antiparallel B. Runs in the opposite direction C. Both a & b D. Consists of Purines only
Option C Antiparallel strands of a DNA molecule means that the phosphate groups at the start of two DNA strands are in opposite position (pole). DNA (Deoxyribonucleic Acid) is composed of two polynucleotide strands (the polymers of nucleotides), which forms what 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. The antiparallel strands twist in a complete DNA structure, forming a double helix. It runs 3'-5' and 5'-3' linkage. The 5' and 3' mean "five prime" and "three prime", which indicate the carbon numbers in the DNA's sugar backbone. The 5' carbon has a phosphate group attached to it and the 3' carbon is a hydroxyl (-OH) group. This asymmetry gives a DNA strand a "direction".
