Question

The ends of eukaryotic chromosomes terminate in a G-rich single-stranded overhang that can fold up on itself to form a four-stranded structure. In this structure, four guanine residues assume a hydrogen-bonded planar arrangement with an overall geometry that can be represented as shown below. Draw the complete structure of this “G quartet,” including the hydrogen bonds between the purine bases.

Short answer

The complete structure of the G quartet, including the hydrogen bonds between the purine bases is,

Step-by-step solution

Define G-quartet.

The G-quartet is an RNA secondary structure made up of four guanine molecules.

In the G-quartet, hydrogen bonds are formed as follows: Oxygen at C⁶, hydrogen at N¹, and amine group hydrogen at N⁷.

Structure of Guanine.

The structure of guanine is given in the diagram below.

Structure of G quartet.

Hence, the complete structure of the G quartet, including the hydrogen bonds between the purine bases is,