Chapter 17, Problem 1P

What purpose do the bla and lacZgenes serve in the plasmid vector $puC18$?

Summary Introduction

To review:

The role of bal and Lac $\text{-}$Z genes in artificially constructed $\text{puC18}$ plasmid.

Introduction:

The $\text{puC18}$ (plasmid for the University of California) is an artificially constructed plasmid. The size of $\text{puC18}$ is approximately $\text{2700 bp}$ long, and it has its own origin of the replication site. $\text{puC18}$ plasmid is used in the recombinant DNA technology. In this plasmid, there are Lac $\text{-}$ Z and bal ($\text{β-}$ lactamase) genes that have a restriction site for specific endonuclease. The gene of interest is placed in the coding sequence of Lac $\text{-}$ Z and bal ($\text{β-}$ lactamase) genes.

Explanation of Solution

Lac $\text{-}$ Z gene encodes $\text{β-}$ galactosidase enzyme; it breaks the lactose into galactose and glucose. Recombinant bacteria having Lac $\text{-}$ Z gene can survive in the absence of glucose and presence of lactose.

On the other hand, bal gene encodes $\text{β-}$ lactamase enzyme having Ampicillin resistant property. So, recombinant bacteria can survive in the presence of Ampicillin.

Both Lac $\text{-}$ Z and bal gene play an important role in positive and negative selection of transgenic recombinant cell in recombinant DNA technology.

Conclusion

Both Lac $\text{-}$ Z and bal gene play an important role in positive and negative selection of transgenic recombinant cell in recombinant DNA technology.