Chapter 15, Problem 1TYU

A plasmid (a) can be used as a DNA vector (b) is a type of bacteriophage (c) is a type of cDNA (d) is a retrovirus (e) b and c

Summary Introduction

Introduction: Plasmids are circular extra-chromosomal DNA molecules present in bacteria. They occur naturally and are self-replicate by themselves. Vector is a kind of plasmid that is manipulated by inserting a foreign DNA into it. This is known as recombinant DNA. It transfers DNA into the host organism. It replicates and expresses in the host organism.

Answer to Problem 1TYU

Correct answer: A plasmid can be used as a DNA vector. Hence, the correct answer is option (a).

Explanation of Solution

Reason for the correct answer:

Option (a) is given as “can be used as a DNA vector”. Plasmids are small extra-chromosomal DNA fragments that occur in bacteria. Bacterial plasmids are used as vectors by inserting a DNA segment of interest into them. These are known as vectors and they act as a vehicle to carry foreign DNA to the host cell. Vector sequence is digested; sequence is inserted; and then it is ligated together in a process known as transformation.

Hence, the correct answer is option (a).

Reasons for incorrect answers:

Option (b) is given as “is a type of bacteriophage”. Bacteriophages are viruses that infect bacteria. Hence, option (b) is incorrect.

Option (c) is given as “is a type of cDNA”. Plasmids are different from a cell’s chromosomal DNA and occur naturally. cDNA is synthesized from mRNA through reverse transcription. Hence, option (c) is incorrect.

Option (d) is given as “a retrovirus”. It is an RNA virus and transfers their genome into the host cell. Hence, option (d) is incorrect.

Option (e) is given as “b and c”. Options (b) and (c) are wrong answer choices. Hence, option (e) is incorrect.

Hence, options (b), (c), (d), and (e) are incorrect.

Conclusion

A plasmid is a small extra-chromosomal DNA segment that can be used as a DNA vector.