What is name of procedure, through which a piece of DNA is introduced in a host bacterium ?

Transformation.

Transformation is a process used in genetic engineering and biotechnology to introduce foreign DNA (often in the form of a plasmid) into bacterial cells. The purpose of transformation is to make the bacterial cells capable of taking up and expressing the foreign DNA, thereby creating recombinant bacteria with new genetic information.

The transformation process typically involves the following steps:

1. Preparation of competent cells: Bacterial cells are treated with a specific concentration of divalent cations, such as calcium, which makes their cell membranes more permeable to DNA.
2. Addition of foreign DNA: The foreign DNA, usually in the form of a plasmid containing the gene of interest, is mixed with the competent bacterial cells.
3. Heat shock: The mixture of foreign DNA and bacterial cells is briefly exposed to a temperature of around 42°C (heat shock) and then quickly placed back on ice. This temperature change helps the foreign DNA to enter the bacterial cells.
4. Uptake of foreign DNA: During the heat shock, the competent bacterial cells take up the foreign DNA from the surrounding environment.
5. Incorporation of foreign DNA: The foreign DNA integrates into the bacterial cell's genome, becoming part of the cell's genetic material.
6. Expression of the foreign gene: The bacterial cells now express the foreign gene and produce the protein encoded by it.

By following this process, scientists can introduce specific genes of interest into bacterial cells, allowing them to study the function of those genes or produce desired proteins for various applications in biotechnology and medicine.