Question

Heat shock method is used to bring about

• A. Electroporation
• B. Transduction
• C. Transformation
• D. Conjugation

Hint:

Remember the classic chemical transformation protocol: Incubation in ice-cold \(\text{CaCl}_2\) \(\rightarrow\) Heat shock at \(42^\circ\text{C}\) \(\rightarrow\) Rapid cooling in ice.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Bacterial transformation is a method of horizontal gene transfer where competent bacterial cells take up free, foreign DNA from their surroundings.

Step 2: Detailed Explanation:
In biotechnology, transformation is used to introduce recombinant plasmid vectors into host cells like E. coli.
To make the cells "competent" to receive DNA, they are treated with divalent cations (such as \(\text{CaCl}_2\)) at low temperatures.
These cations neutralize the negative charges on both the plasmid DNA and the bacterial outer membrane, allowing the DNA to associate with the cell surface.
The mixture is then subjected to a brief "heat shock" at \(42^\circ\text{C}\) for approximately 45-90 seconds, before being returned to ice.
This thermal shock alters the fluidity of the cell membrane, creating transient pores that allow the plasmid DNA to enter the bacterial cytoplasm.

Step 3: Final Answer:
The heat shock method is used to bring about Transformation.