Question

6. Which are the nucleotides “portions” that bind in the formation of nucleic acids? What is meant by the 5’ and 3’ extremities of nucleic acids?

Answer 1

The phosphate group of one nucleotide binds to the pentose of the other nucleotide and so on to make the polynucleotide chain.

Each extremity of a DNA or RNA chain can be distinguished from the other extremity according to their terminal chemical entity. The phosphate-ended extremity is called 5’-extremity and the pentose-ended extremity is called 3’-extremity. So DNA or RNA chains can be run along the 5’-3’ way or along the 3’-5’ way. These ways are important in several biological functions of DNA and RNA since some reactions specifically occur following one way or the other way.