Chapter 28, Problem 28.19P

(a)

Interpretation Introduction

Interpretation:

One alternative tautomeric structure for Adenine has to be written.

Concept Introduction:

The isomers which differ in the position of the protons and electrons and the carbon skeleton is same are said to be Tautomers and the mechanism is known as Tautomerism.  The common example for Tautomerism is keto-enol tautomerization.  The keto group is converted to enol (alcohol) group by the intramolecular exchange of protons.

(b)

Interpretation Introduction

Interpretation:

Will the tautomeric structure of Adenine base pairs with Thymine or any other base has to be given.

Concept Introduction:

In the DNA double helix, the bases are paired with each other on the adjacent strands to hold the double helix.  The bases present in DNA are Adenine, Guanine, Cytosine and Thymine.  The pairing occurs between the Adenine and Thymine (A-T) and Guanine and Cytosine (G-C).