Biotechnology Principles and Processes Class 12 Notes Biology Chapter 11 - CBSE


What are Biotechnology Principles and Processes?

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    It is defined as the technology that utilizes biological systems, living organisms or their parts to produce commercially or medically important products. ‘The integration of natural science and organisms, cells, their parts and molecular analogues for products and services’.

    Principles of Biotechnology

    Genetic Engineering

    • ➥ Genetic Engineering deals with the manipulation of genes, and introduction of these into host organisms.

    Bioprocess Engineering

    • ➥ Provides suitable sterile conditions so that only desirable microbes can grow which are used for the production of biotechnological products like antibiotics, vaccines, enzymes, etc.

    Construction of an Artificial Recombinant DNA Molecule

    The gene of interest is identified and is cut at specific locations by the help of restriction enzymes (Molecular scissors).

    DNA of interest is attached with the origin of replication which will initiate the process of replication in the host cell.

    The gene of interest is linked with plasmid (Extra chromosomal genetic material) with the help of ligase. Plasmid provides antibiotic resistance gene that will help in the process of selection of recombinants.

    These “recombinant DNA” (rDNA) molecules are then introduced into host cells, where they can be propagated and multiplied.

    Tools of Recombinant DNA Technology

    • ➥ Restriction Enzymes
    • ➥ Polymerase Enzymes
    • ➥ Ligases
    • ➥ Vectors
    • ➥ Host organism

    Restriction Enzymes (Molecular Scissors)

    Restriction enzymes belong to a large class of enzymes called Nucleases. They are named so because they restrict the growth of bacteriophage in Escherichia coli.

    Types of Restriction Enzymes


    • ➥ Removes nucleotides from the ends of the DNA


    • ➥ Make cuts at specific position within the DNA.

    Nomenclature Of Enzymes

    Scientific name should consists of two letters. First should be genus and second should be the name of species of the prokaryotic cell from which they were isolated, e.g., EcoRI comes from Escherichia coli RY 13. Letter ‘R’ is derived from the name of strain. Roman numbers indicates the order in which the enzymes were isolated from that strain of bacteria.

    Separation And Isolation Of Dna Fragments (Dna Of Interest)

    Fragments of DNA obtained after the action of restriction enzymes are separated by Gel Electrophoresis.

    The DNA fragments are separated according to their size. Heavy molecules move slowly and thus can be seen near the walls.

    The separated DNA fragments can be visualized only after staining the DNA with Ethidium bromide.

    Gel is exposed to UV rays which shows bright orange coloured bands.

    The separated bands of DNA are cut out from the agarose gel and are extracted from the gel. This step is known as Elution.

    These DNA fragments are purified and used for further experiments.

    Cloning Vectors (Vehicles For Cloning)

    Vector is any vehicle (Virus, plasmid, bacteria) that help to carry a foreign gene of interest into a given host cell.

    Salient Features Of A Vector

    Cloning vectors should have following features:

    • Cloning vector has origin of replication (ori) so that it can multiply within the host cell. Ori site is also responsible for high copy number of the cloned DNA.
    • A selectable marker (antibiotic resistance gene like ampicillin, chloramphenicol, tetracycline etc), which will allow to select recombinant cells from non recombinants one by the process of transformation.
    • Cloning vector should have at least one unique cloning/restriction endonuclease recognition site to enable foreign DNA to be inserted into the vector.

    Transformation Of Host Cell

    Host cell is made competent to accept the DNA molecule which is hydrophilic in nature.


    Cells are incubated with divalent calcium ion Ca2+ to increase the efficiency of cell wall (through pores of cell wall) to take up the rDNA.

    rDNA is forced to enter into the cell by incubating both on ice

    Then place them briefly at 42°C - Heat Shock

    Put them back on ice

    Direct Methods of Injecting rDNA Into The Host Cells

    • Microinjection
    • Biolistics / Gene gun method
    • Disarmed Pathogen-Vectors

    Processes Of Recombinant Dna Technology

    Sequential steps of rDNA technology are as follows:

    • Isolation of DNA.
    • Fragmentation of DNA by restriction endonucleases.
    • Isolation of desired DNA fragment.
    • Ligation of the DNA fragment into a vector.
    • Transferring the recombinant DNA into the host cells.
    • Culturing the host cells in a medium at large scale and extraction of the desired product.

    Obtaining The Foreign Gene Product

    The cells harboring cloned genes of interest may be grown on a small scale in the laboratory. The cultures may be used for extracting the desired protein and then purifying it by using different separation techniques.


    A bioreactor provides the optimal conditions for achieving the desired product in large quantities by providing optimum growth conditions (temperature, pH, substrate, salts, vitamins, oxygen). There are two types of bioreactors :

    (i) Simple Stirred-tank Bioreactor

    (ii) Sparged Stirred-tank Bioreactor

    Downstream Processing

    • The processes of separation and purification are included in downstream processing
    • Each product is tested for its quality and then released in the market. The downstream processing and quality control testing vary from product to product.