CBSE Class 12 Biology Chapter 11 Revision Notes Part 1

Chapter 11: Biotechnology: Principles and Processes Revision Notes Part 1

European Federation of technology defines Biotechnology as ‘The integration of natural science and organisms, cells, parts thereof, and molecular analogs for products and services.

Biotechnology has been practiced by human society since the immemorial time in activities such as baking bread, brewing alcoholic beverages, or breeding food crops or domestic animals. But today, biotechnology has transformed a lot and has become much more complex in its applications with the help of new principles and processes.

In today’s time, we define biotechnology as the technology to alter the genetic makeup of living things for human purposes. Biotechnology primarily finds its usage in creating organisms that are much more useful to humans, or tend to cure genetic disorders.

It is also used in creating crops that resist insects or pests or to create crops or creating better drugs or treatments. Traditionally biotechnology only used microbes to generate products for human use, but with time, it evolved and is currently making use of DNA/genes.

Principles of Biotechnology

Modern biotechnology is based on two core techniques:

1. Genetic Engineering – Genetic Engineering is the technique used to alter the chemistry of genetic materials (DNA or RNA) so that they can be used in the host organisms, thus changing the phenotype in the host organisms. Specific applications of genetic engineering are a lot and are rapidly increasing. Genetic engineering is nowadays being used in the production of pharmaceuticals, gene therapy, the development of transgenic plants and animals, and in many more spheres.

With the help of genetic engineering, virtually any desirable trait found in nature can, in principle, be transferred into any chosen organism. An organism modified by genetic engineering is called transgenic.

2. Bioprocess Engineering – Maintenance of a sterile i.e., microbial contamination-free environment to enable the growth of only desired microbes/eukaryotic cells in an abundant quantity to create biotechnological products. (vaccines, enzymes, antibiotics, etc.) . Along with the production, it also helps in the storage of these biotechnological products.

Conceptual Development of the Principles of Genetic Engineering

DNA Cloning Source

Gene Cloning – The process of isolating and making copies (clones) of genes is termed gene cloning. Gene cloning is used in gene therapy. The gene cloning process involves four steps- isolation, ligation, transformation, and selection.

Isolation – In this process, a gene is isolated by breaking the DNA at a specific base sequence with the help of a restriction enzyme.

Ligation – In this process, the DNA ligase combines the isolated gene with plasmid DNA from bacteria. The resultant DNA is called recombinant DNA.

Transformation – In this process, the recombinant DNA is inserted into a living cell. This is a way to change an organism through genetic engineering.

Selection – In this process, transformed bacteria are grown to ensure that they have recombinant DNA. This is a necessary step because transformation is not always successful. Only bacteria that contain the recombinant DNA are selected for further usage.

Polymerase chain reaction (PCR)- PCR makes many copies of a gene or other DNA segment. It enables us to make a large quantity of genes for gene testing. Polymerase chain reaction involves three steps, namely, denaturing, annealing and extension. To make copies of genes in a big quantity, these steps are repeated in a cycle several times.

Denaturing – In this process, the DNA is heated so that the bond joining the two DNA strands is broken, yielding two sets of single DNAs.

Annealing – In this process, the single DNA strand is cooled and then mixed with primers (the short DNA segment). A bond is formed between the DNA strands and the primer. Primers have a base sequence that is complementary to the single DNA strand segments. That is why it works.

Extension – In this process, when an enzyme(Taq Polymerase, Taq DNA Polymerase) adds nucleotides to the primers, extension happens. This produces new DNA molecules, each incorporating one of the original DNA strands.

Recombinant DNA Technology

Recombinant DNA technology is a very strong aspect of genetic engineering. It is the technology of joining together DNA molecules of two different species. It is inserted in the host organism to produce a new and better genetic combination, which is of far more importance to the human kind.

Recombinant DNA Technology requires several tools like Restriction Enzymes, Cloning Vector, Competent host, etc.

Steps of Recombinant DNA Technology

  • DNA with desired genes is selected.
  • Transfer of recombinant DNA into the host is done.
  • Maintenance and keeping a check that the introduced DNA is passed to the next generation of the host.


Principles and processes Accessed on 21 Dec, 2021


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