Question

Antiparallel strands of DNA molecule means

• A. Phosphate groups at the start of two DNA strands are in opposite position
• B. One strand turns clockwise
  
• C. Phosphate groups of the two strands share the same position at their ends
• D. One strand turns anticlockwise

Answer 1

The correct option is A Phosphate groups at the start of two DNA strands are in opposite position

Answer

Antiparallel

. One end of the polynucleotide chain has a sugar residue with a free 5’ carbon attached to a phosphate group that is not linked. This end is called the $5$’ end.

. The other end has a sugar residue with a free $3$’ carbon attached to a -OH group that is not linked. This end is called the $3$’ end.

. The two DNA strands are said to be antiparallel as they run parallel but are oriented in opposite directions, i.e, the $3$’ end of one polynucleotide chain lies opposite to the $5$’ end of the other.

. This indicates that the phosphate groups at the start of two DNA strands are in opposite position.

Final answer

d. Phosphate groups at the start of two DNA strands are in opposite position