Question

The copy number of a plasmid in bacterial cells can be determined by

• A. western blotting
• B. southern blotting
• C. northern blotting
• D. quantitative polymerase chain reaction

Hint:

Quantitative PCR (qPCR) allows the quantification of specific DNA sequences and can be used to determine the plasmid copy number in bacterial cells.

Answer 1

The Correct Option is B, D

Step 1: Understanding the techniques.
Plasmid copy number refers to the number of plasmid molecules in a cell. Quantitative PCR (qPCR) is a technique that allows the determination of the plasmid copy number by measuring the amplification of specific DNA sequences.

Step 2: Analyzing the options.
(A) western blotting: Western blotting is used for detecting specific proteins, not DNA, so it is not used to determine plasmid copy number.
(B) southern blotting: Southern blotting is used for detecting specific DNA sequences, but it does not quantify plasmid copy number directly.
(C) northern blotting: Northern blotting is used for detecting RNA sequences, not DNA, and is not used for determining plasmid copy number.
(D) quantitative polymerase chain reaction: Correct — Quantitative PCR (qPCR) is a reliable method to determine the copy number of plasmids in bacterial cells by measuring the amplification of specific DNA regions.

Step 3: Conclusion.
The correct answer is (D) quantitative polymerase chain reaction, as it is the most accurate and widely used method for determining plasmid copy number.