Final answer:
Polynucleotides are chains of nucleotides linked by phosphodiester bonds, forming the backbone of DNA and RNA. They are polar and have an overall negative charge due to the negatively charged phosphate backbone. Their structure is crucial for genetic information storage and transfer.
Step-by-step explanation:
Polynucleotides are long chains of nucleotides linked together by phosphodiester bonds. These bonds are formed during a condensation or dehydration synthesis reaction, which occurs between the hydroxyl group on the 3'-carbon of one nucleotide's sugar and the phosphate group on the 5'-carbon of another. As a result of this linkage, polynucleotides have a directionality, with a free 5'-phosphate group at one end and a free 3'-hydroxyl group at the other, and are written from the 5' to the 3' end, for example, 5'-A-A-T-C-T-G-G-C-A-C-T-3'.
Polynucleotides are the basis for the nucleic acids DNA and RNA, which are essential for genetic information storage and transfer. In DNA, the sugar present is deoxyribose, whereas in RNA, it is ribose. The difference in sugars affects the structure and function of the resulting nucleic acids. Polynucleotides are polar due to the presence of a phosphate backbone that carries a negative charge, which contributes to the molecule's overall negative charge under physiological conditions.
The role of nitrogen bases attached to the nucleotides is crucial as they determine the genetic code and facilitate the formation of the double-stranded structure of DNA through complementary base pairing.