Final answer:
The covalent linkage between nucleotides in a dinucleotide is a phosphodiester bond. It forms the backbone of nucleic acid chains and is established through dehydration synthesis reactions.
Step-by-step explanation:
The covalent linkage between the nucleotides in a dinucleotide is a phosphodiester bond. This type of bond is crucial for the structure of DNA and RNA, forming the sugar-phosphate backbone of the nucleic acid chain.
Phosphodiester bonds are created through dehydration synthesis reactions where a hydroxyl group from the 3' carbon of one nucleotide and a hydrogen atom from the 5' carbon of another nucleotide are removed, producing water as a byproduct and establishing the bond.
A phosphodiester linkage involves two phosphate ester bonds, joining the pentose sugars to the phosphate group and adding directionality to nucleic acids, with a distinct 5' end and a 3' end.