Chapter 17, Problem 1U

Summary Introduction

Introduction:

Recombinant DNA is defined as the joining of two different DNA from two different species and then the integrated DNA transformed into the host. This technology is termed as recombinant DNA technology and used in science, medicine and agriculture.

Answer to Problem 1U

Correct answer:

A recombinant DNA molecule is constructed from DNA from different sources. Therefore, option (b) is correct.

Option (b) is given as “constructed from DNA from different sources”.

Explanation of Solution

Justify reason for the correct statement:

Recombinant DNA technology also known as genetic engineering is a technique that involves alteration of genotypes as well as phenotypes of organisms. This technology isolates DNA from donor organisms (human, plant, or microorganism) and inserts them into recipient organisms after genetic manipulation. Thus, the construction of DNA takes place from different sources. The important tools used for manipulation of genotype and phenotypes are nucleic acids, restriction enzymes, ligase, vectors, reverse transcriptase, and mutagens.

Hence, option (b) is correct.

Justify reasons for the incorrect statements:

Option (a) is given as “produced through the process of crossing over that occurs in meiosis”.

The DNA that is formed after meiosis has undergone crossing over but the source of DNA (parent cell) is same while recombinant DNA is constructed by using DNA from different sources. Hence, it is a wrong answer.

Option (c) is given as “constructed from novel combinations of DNA from the same source”.

DNA from same source is not used in recombinant DNA technology. Hence, it is a wrong answer.

Option (d) is given as “produced through mitotic cell division”.

Mitotic cell division results in same kind of DNA which cannot be used in recombinant technique. Hence, it is a wrong answer.

Hence, options (a), (c), and (d) are incorrect.

Conclusion

Construction of recombinant DNA requires DNA from different sources.