In nucleic acids, the Nucleotides are joined together by

Phosphodiester linkage

The correct answer is option 2. Phosphodiester linkage.

Nucleic acids, such as DNA (deoxyribonucleic acid) and RNA (ribonucleic acid), are polymers made up of repeating units called nucleotides. Nucleotides consist of three main components: a phosphate group, a five-carbon sugar, and a nitrogenous base.

In the structure of nucleic acids, nucleotides are joined together by phosphodiester linkages. Let's break down this process:

1. Phosphate Group (P):  Each nucleotide contains a phosphate group, which consists of a phosphorus atom bonded to four oxygen atoms. The phosphate group is negatively charged.

2. Five-Carbon Sugar:
In DNA, the sugar is deoxyribose.
In RNA, the sugar is ribose.

3. Nitrogenous Base (N):
Adenine (A), Thymine (T), Cytosine (C), and Guanine (G) are the nitrogenous bases in DNA.
Adenine (A), Uracil (U), Cytosine (C), and Guanine (G) are the nitrogenous bases in RNA.

The nucleotides are joined together through phosphodiester linkages during the process of nucleic acid synthesis. This involves the formation of a covalent bond between the phosphate group of one nucleotide and the sugar molecule of the adjacent nucleotide.

The linkage occurs between the 3' carbon of one sugar molecule and the 5' carbon of the next sugar molecule. This creates a chain of repeating units with a sugar-phosphate backbone. The resulting backbone is directional, and the two ends of the nucleic acid strand are referred to as the 5' end (where the phosphate group is attached to the 5' carbon of the sugar) and the 3' end (where the phosphate group is attached to the 3' carbon of the sugar).

In summary, the phosphodiester linkage is a covalent bond formed between the phosphate group of one nucleotide and the sugar molecule of the next nucleotide, creating a continuous chain of nucleotides in the structure of nucleic acids.