Principles of Biotechnology - Biology Class 12 - NEET PDF Download

Table of Contents
1. Biotechnology: Meaning and Scope
2. Principles of Biotechnology
3. Conceptual Basis of Genetic Engineering
4. Fate of Alien DNA in a Host Organism
5. Construction of Recombinant DNA: First Experiment
6. Role of Enzymes in Recombinant DNA Technology
7. Vectors and Gene Transfer
8. Basic Steps in Genetic Modification
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Biotechnology: Meaning and Scope

Biotechnology involves techniques that use living organisms or enzymes derived from organisms to produce products and processes useful to humans. Traditional activities such as making curd, bread, and wine are also forms of biotechnology because they involve microbe-mediated processes. In modern usage, biotechnology is applied in a restricted sense, referring mainly to processes that use genetically modified organisms (GMOs) to produce products on a large scale.

Apart from GMOs, biotechnology also includes:

• In vitro fertilisation leading to a test-tube baby
• Gene synthesis and use
• Development of DNA vaccines
• Correction of defective genes

Definition by European Federation of Biotechnology (EFB)

The European Federation of Biotechnology (EFB) defines biotechnology as: "The integration of natural science and organisms, cells, parts thereof, and molecular analogues for products and services." This definition includes both traditional biotechnology and modern molecular biotechnology.

Principles of Biotechnology

Modern biotechnology is based on two core techniques:

1. Genetic Engineering

Genetic engineering refers to techniques used to:

• Alter the chemistry of genetic material (DNA and RNA)
• Introduce modified genetic material into host organisms
• Change the phenotype of the host organism

It allows precise manipulation of genes to achieve desired traits.

2. Bioprocess Engineering

Bioprocess engineering involves:

• Maintaining a sterile, contamination-free environment
• Ensuring growth of only the desired microbe or eukaryotic cell

It enables large-scale production of: Antibiotics, Vaccines, Enzymes and Other biotechnological products

Conceptual Basis of Genetic Engineering

Sexual vs Asexual Reproduction

Asexual reproduction:

• Preserves genetic information
• Produces genetically identical offspring

Sexual reproduction:

• Produces variation
• Creates new genetic combinations
• Some variations may be beneficial to the organism or population

Limitations of Traditional Hybridisation

Traditional plant and animal breeding often results in: Transfer of undesirable genes along with desirable ones

Genetic engineering overcomes this limitation by:

• Allowing isolation and transfer of only selected desirable genes
• Preventing introduction of unwanted genes into the target organism

Fate of Alien DNA in a Host Organism

When foreign (alien) DNA enters a host organism: It cannot multiply independently in progeny cells

For multiplication and inheritance: The alien DNA must integrate into the host genome

Chromosomes contain a specific DNA sequence called the origin of replication: It initiates DNA replication

Therefore:

• Alien DNA must be linked to an origin of replication
• Only then can it replicate and be inherited

This process of making multiple identical copies of DNA is called cloning

Construction of Recombinant DNA: First Experiment

The first artificial recombinant DNA was constructed by: Stanley Cohen and Herbert Boyer in 1972.

Source of DNA

An antibiotic resistance gene was isolated from a plasmid of Salmonella typhimurium

Plasmids are: Circular, Extra-chromosomal and Autonomously replicating DNA molecules.

Role of Enzymes in Recombinant DNA Technology

Restriction Enzymes

• Known as molecular scissors
• They cut DNA at specific recognition sites
• Used to isolate the desired gene from donor DNA

DNA Ligase

• Joins cut DNA fragments by sealing their ends
• Enables: Linking of the antibiotic resistance gene to the plasmid
• Produces a new DNA combination formed in vitro

Vectors and Gene Transfer

The plasmid acts as a vector: Transfers alien DNA into the host organism. Similar to how: A mosquito acts as a vector for malarial parasite. The recombinant plasmid was introduced into Escherichia coli.  
Inside E. coli:

• The recombinant DNA replicated using the host's DNA polymerase
• Multiple copies of the antibiotic resistance gene were produced

This process is called cloning of the antibiotic resistance gene.

Basic Steps in Genetic Modification

There are three fundamental steps in genetically modifying an organism:

1. Identification of DNA containing desirable genes

2. Introduction of the identified DNA into the host organism

3. Maintenance and inheritance of the introduced DNA in the host and its progeny