Question

What is the meaning of polarity of DNA?

• A. DNA is positively charged on one end and negatively charged on others.
• B. One strand of DNA is positively charged while other is negatively charged.
• C. DNA has two distrinct ends, one is called 3' -end and other 5' -end.
• D. None of the above

Answer 1

The correct option is C

DNA has two distrinct ends, one is called 3' -end and other 5' -end.

A single nucleic acid strand has a backbone composed of repeating pentose-phosphate units from which the purine and pyrimidine bases extend as side groups. The
5' end has a hydroxyl or phosphate group on the 5' carbon of its terminal sugar; the 3' end usually has a hydroxyl group on the 3' carbon of its terminal sugar. This structure gives a distinct polarity to the DNA strand.