question_answer

(i) What are the main techniques that gave birth to modern biotechnology?

(ii) What are the three basic steps for the genetic modification of an organism?

Or

(i) What is the role of selectable marker in a cloning vector?

(ii) Why the coding sequence of \[\alpha \] - galactosidase is considered a better marker than the others found in pBR322 cloning vector? Explain.

Answer:

(i) The main techniques that gave birth to modern biotechnology are

I. Genetic engineering This is a technique used to alter the chemistry of genetic material (DNAand RNA) before its insertion into host organism to change organism's phenotypic characters.

II. Chemical engineering These methods are used to maintain the growth of desired microbes or cells in contamination - free condition to produce large quantities of biotechnological products like vaccines, enzymes, antibiotics, etc.

(ii) Three basic steps for the genetic modification of an organism are as follows

I. Identification of DNA with desirable genes and introduction of this identified DNA into the host.

II. Maintenance of introduced DNA in the suitable host to form recombinant DNA.

III. Maintenance of introduced DMA in particular and gene cloning.

IV. Transfer of the DNA to its progeny.

Or

(i) Selectable marker helps in identifying or selecting transformants and eliminating non - transformants by selectively permitting the growth of the transformants.

(ii) The coding sequence of \[\alpha \]- galactosidase enzyme is considered a better marker than others found in pBR 322, i.e. \[am{{p}^{R}}\]and \[te{{t}^{R}}\], because it differentiates recombinants from non-recombinants on the basis of their ability to produce colour in the presence of a chromogenic substrate. In this method, a recombinant DNA is inserted in the coding sequence of \[\beta \]- galactosidase enzyme which results in the inactivation of this enzyme. This is referred to as insertional inactivation. The recombinants do not produce any colour due to Insertional inactivation of \[\alpha \] - galactosidase while, non-recombinants produce blue colonies.