Chapter 12, Problem 1P

Interpretation Introduction

Interpretation: The possible products of the ligation reaction are to be stated.

Concept introduction: DNA stands for deoxyribonucleic acid, is a biological macromolecule. In organisms, it carries genetic information and is required for protein production, cell reproduction, regulation and metabolism.

A plasmid refers to a DNA molecule of a smaller size in a cell that is separated from chromosomal DNA and capable of replicating independently.

Answer to Problem 1P

The possible products of the ligation reaction are the linear molecule that is made up of several copies of the DNA fragment, linear and circular molecules with multiple molecules of plasmid and a linear or circular molecule with two forms of DNA hybrids.

Explanation of Solution

The digestion with $Eco\text{RI}$ generates both the DNA fragment and the plasmid. This simply means that both the plasmid and the DNA fragment have the same “sticky ends.” All the possible products will result in the annealing of these sticky ends. The ends of one DNA fragment combine with the ends of another DNA fragment and this results in the formation of a long linear molecule. The linear molecule consists of multiple copies of the DNA fragment. The ends of these molecules also join together to form a circular molecule.

Similarly, one plasmid also combines with other plasmids. This could produce linear and circular molecules containing multiple plasmid molecules.

It is also possible to combine the DNA fragment with the plasmid. This could form a linear or circular molecule that would be hybrids of the two forms of DNA.