Question

In the formation of a polynucleotide (a short portion of the DNA molecule), which components (sugar, base, or phosphate) on adjacent nucleotides bond to each other?

Short answer

In the formation of a polynucleotide, the sugar component of one nucleotide bonds with the phosphate group of the adjacent nucleotide, forming a sugar-phosphate backbone. These bonds are called phosphodiester bonds and link the nucleotides together to form a polynucleotide chain.

Step-by-step solution

Understand the Concept of a Nucleotide

Each nucleotide of DNA is composed of a sugar (deoxyribose), a phosphate group, and a nitrogenous base. There are four types of nitrogenous bases in DNA: Adenine (A), Cytosine (C), Guanine (G) and Thymine (T).

Understand the DNA Polynucleotide Structure

In the DNA structure, nucleotides are linked together to form a polynucleotide chain. The sugar and phosphate portions of each nucleotide form the backbone of the DNA strand while the nitrogenous bases are on the inside. The sugar of one nucleotide and the phosphate of the next nucleotide are covalently bonded, creating a sugar-phosphate backbone.

Identify the Bonds Between Adjacent Nucleotides

The components on adjacent nucleotides that bond to each other are the phosphate group of one nucleotide and the sugar of the next nucleotide. A covalent bond is formed between the third carbon atom of the sugar and the phosphate group attached to the 5th carbon of the next sugar. This bond is known as a phosphodiester bond. These bonds between the sugar of one nucleotide and the phosphate of the next nucleotide continue along the backbone of the DNA strand, linking the nucleotides together to form a polynucleotide.

Conclude

Therefore, during the formation of a polynucleotide or a DNA molecule, the sugar of one nucleotide binds with the phosphate of the adjacent nucleotide. This sugar-phosphate linkage forms the backbone of the DNA helix, and the nitrogenous bases (A, T, C, G) are oriented towards the inside.