Chapter 13, Problem 18A

Summary Introduction

To predict:

The result of growing transformed bacteria with recombinant DNA plasmid without an antibiotic.

Introduction:

Researchers use genetic engineering to manipulate DNA. It makes possible to produce organisms that contain individual genes from another organism. Recombinant DNA contains DNA from different sources.A plasmid DNA and a DNA fragment obtained from another genome are joined to create a recombinant plasmid DNA.

Answer to Problem 18A

Both types of bacteria; the transformed bacteria with recombinant DNA plasmid and those without recombinant DNA plasmid; will continue to grow as there is no antibiotic.

Explanation of Solution

To make large quantities of recombinant plasmid DNA, bacterial cells are mixed with recombinant plasmid DNA. Some bacteria take up the recombinant plasmid DNA through a process called transformation. Brief heating or short electric pulse creates openings in the plasma membrane of bacterial cells which allow recombinant plasmid DNA to enter the bacterial cells. The bacteria is said to be transformed. It can make multiple copies of recombinant plasmid DNA during cell replication. Large numbers of identical bacteria, each containing inserted DNA molecules are produced through cloning.

Now the transformed bacteria have to be separated from non-transformed bacteria. Both groups are identical so their separation involves growing them on a plate containing an antibiotic. The transformed bacteria are able to survive as they contain the gene for antibiotic resistance and the normal bacteria die.

If the transformed bacteria with recombinant DNA plasmid are grown without an antibiotic, both types of bacteria will survive and it would not be possible to obtain only transformed bacteria.