Nucleic Acids

To solve the problem, we need to determine how nucleotides are joined together in a biological context.

1. Understanding Nucleotides:
Nucleotides are the building blocks of nucleic acids, such as DNA and RNA. Each nucleotide consists of a sugar molecule, a phosphate group, and a nitrogenous base.

2. Identifying the Bond:
In nucleic acids, nucleotides are linked to form a polynucleotide chain. The bond that joins nucleotides is formed between the phosphate group of one nucleotide and the sugar (specifically, the 3’ hydroxyl group) of the adjacent nucleotide. This bond is called a phosphodiester bond, which creates the sugar-phosphate backbone of DNA or RNA.

3. Confirming the Specificity:
The phosphodiester bond is specific to the covalent linkage between nucleotides in nucleic acids. Other types of bonds (e.g., hydrogen bonds) are involved in base pairing between strands, but the question focuses on joining nucleotides within a single strand.

Final Answer:
Nucleotides are joined together by phosphodiester bonds.