NCERT Textbook: An Overview of Recombinant DNA Technology | Biotechnology for Class 12 - NEET PDF Download

 Page 1


UNIT  I
Recombinant DNA 
Technology
Chapter 1: An Overview of Recombinant DNA Technology
Chapter 2: Host–Vector System
Chapter 3: Gene Cloning
Chapter 4: Application of Recombinant DNA Technology
Chapter 1 Recombinant DNA Tec.indd   1 23-01-2025   11:18:46
Reprint 2025-26
Page 2


UNIT  I
Recombinant DNA 
Technology
Chapter 1: An Overview of Recombinant DNA Technology
Chapter 2: Host–Vector System
Chapter 3: Gene Cloning
Chapter 4: Application of Recombinant DNA Technology
Chapter 1 Recombinant DNA Tec.indd   1 23-01-2025   11:18:46
Reprint 2025-26
Herbert Wayne ‘Herb’ Boyer (born July 10, 1936) was a researcher 
and entrepreneur in Biotechnology. Herb Boyer hails from 
Derry, Pennsylvania. Boyer went on to graduate at the University 
of Pittsburgh, where he specialised in microbial genetics. After 
preliminary experiments in 1973, the Cohen-Boyer team was able 
to cut open a plasmid loop from one species of bacteria, insert 
a gene from di??erent bacterial species and close the plasmid.  
This created a recombinant—plasmid containing recombined 
DNA from two di??erent sources. The team had created the ??rst 
genetically modi??ed organisms. He is the recipient of the 1990 
National Medal of Science, co-recipient of the 1996 Lemelson–
MIT Prize, and a co-founder of Genentech. He was a professor 
at the University of California, San Francisco (UCSF) and later 
served as the Vice President of Genentech from 1976 until his 
retirement in 1991.
Herbert Boyer
Chapter 1 Recombinant DNA Tec.indd   2 23-01-2025   11:18:46
Reprint 2025-26
Page 3


UNIT  I
Recombinant DNA 
Technology
Chapter 1: An Overview of Recombinant DNA Technology
Chapter 2: Host–Vector System
Chapter 3: Gene Cloning
Chapter 4: Application of Recombinant DNA Technology
Chapter 1 Recombinant DNA Tec.indd   1 23-01-2025   11:18:46
Reprint 2025-26
Herbert Wayne ‘Herb’ Boyer (born July 10, 1936) was a researcher 
and entrepreneur in Biotechnology. Herb Boyer hails from 
Derry, Pennsylvania. Boyer went on to graduate at the University 
of Pittsburgh, where he specialised in microbial genetics. After 
preliminary experiments in 1973, the Cohen-Boyer team was able 
to cut open a plasmid loop from one species of bacteria, insert 
a gene from di??erent bacterial species and close the plasmid.  
This created a recombinant—plasmid containing recombined 
DNA from two di??erent sources. The team had created the ??rst 
genetically modi??ed organisms. He is the recipient of the 1990 
National Medal of Science, co-recipient of the 1996 Lemelson–
MIT Prize, and a co-founder of Genentech. He was a professor 
at the University of California, San Francisco (UCSF) and later 
served as the Vice President of Genentech from 1976 until his 
retirement in 1991.
Herbert Boyer
Chapter 1 Recombinant DNA Tec.indd   2 23-01-2025   11:18:46
Reprint 2025-26
1
Chapter 
This chapter gives an overview of recombinant DNA (rDNA) 
technology as to how the application of basic concepts of 
molecular biology, microbiology, genetics, biochemistry, 
etc., led to initial development of rDNA technology. 
Potential application of rDNA technology in the ??eld of 
medicine and agriculture is also discussed in conceptual 
manner along with some noticeable examples of products 
developed through rDNA technology.
1.1 An Overview Of r ec Ombin Ant Dn A 
t echn Ol Ogy In the last century when scientists discovered that 
nucleic acid (DNA) is the principal molecule responsible 
for the expression of characters, attempts were made to 
alter the genetic makeup of an organism by manipulating 
nucleic acid directly. Various methods used for directly 
manipulating nucleic acid/genome of an organism 
are collectively referred to as recombinant DNA (rDNA) 
technology or genetic engineering.
rDNA technology has been possible due to rapid 
progress in various ??elds of biology, which spans from 
An Overview of Recombinant
DNA Technology 
1.1 An Overview of 
Recombinant  
DNA Technology  
Chapter 1 Recombinant DNA Tec.indd   3 23-01-2025   11:18:46
Reprint 2025-26
Page 4


UNIT  I
Recombinant DNA 
Technology
Chapter 1: An Overview of Recombinant DNA Technology
Chapter 2: Host–Vector System
Chapter 3: Gene Cloning
Chapter 4: Application of Recombinant DNA Technology
Chapter 1 Recombinant DNA Tec.indd   1 23-01-2025   11:18:46
Reprint 2025-26
Herbert Wayne ‘Herb’ Boyer (born July 10, 1936) was a researcher 
and entrepreneur in Biotechnology. Herb Boyer hails from 
Derry, Pennsylvania. Boyer went on to graduate at the University 
of Pittsburgh, where he specialised in microbial genetics. After 
preliminary experiments in 1973, the Cohen-Boyer team was able 
to cut open a plasmid loop from one species of bacteria, insert 
a gene from di??erent bacterial species and close the plasmid.  
This created a recombinant—plasmid containing recombined 
DNA from two di??erent sources. The team had created the ??rst 
genetically modi??ed organisms. He is the recipient of the 1990 
National Medal of Science, co-recipient of the 1996 Lemelson–
MIT Prize, and a co-founder of Genentech. He was a professor 
at the University of California, San Francisco (UCSF) and later 
served as the Vice President of Genentech from 1976 until his 
retirement in 1991.
Herbert Boyer
Chapter 1 Recombinant DNA Tec.indd   2 23-01-2025   11:18:46
Reprint 2025-26
1
Chapter 
This chapter gives an overview of recombinant DNA (rDNA) 
technology as to how the application of basic concepts of 
molecular biology, microbiology, genetics, biochemistry, 
etc., led to initial development of rDNA technology. 
Potential application of rDNA technology in the ??eld of 
medicine and agriculture is also discussed in conceptual 
manner along with some noticeable examples of products 
developed through rDNA technology.
1.1 An Overview Of r ec Ombin Ant Dn A 
t echn Ol Ogy In the last century when scientists discovered that 
nucleic acid (DNA) is the principal molecule responsible 
for the expression of characters, attempts were made to 
alter the genetic makeup of an organism by manipulating 
nucleic acid directly. Various methods used for directly 
manipulating nucleic acid/genome of an organism 
are collectively referred to as recombinant DNA (rDNA) 
technology or genetic engineering.
rDNA technology has been possible due to rapid 
progress in various ??elds of biology, which spans from 
An Overview of Recombinant
DNA Technology 
1.1 An Overview of 
Recombinant  
DNA Technology  
Chapter 1 Recombinant DNA Tec.indd   3 23-01-2025   11:18:46
Reprint 2025-26
Biotechnology XII 4
biochemistry, genetics, cytology, microbiology, molecular 
biology and others. Isolation and puri??cation of nucleic 
acids followed by the understanding of their structures, 
properties, functions and ??nally their sequencing in the 
last century are the most important contributions, which 
laid the foundation of development of rDNA technology. 
The ??rst breakthrough in this journey was to establish the 
fact that DNA of an organism not only carries its genetic 
information but also propagates it from one generation 
to another. The next hallmark was the determination of 
chemical and physical structure of DNA molecule and 
double helical structure of DNA. Further, replication, 
transcription and translation of DNA was understood in 
detail by scientists.  Scientists were also able to develop 
various methods and techniques to isolate and purify 
DNA from various organisms. Several enzymes were 
simultaneously discovered using which one can precisely 
manipulate a DNA molecule. Thus, new enzymes, such 
as restriction enzymes (which act as scissors to cut the 
molecules of DNA) by Werner Arbor, Hamilton Smith 
and Daniel Nathan (during late 1960s and early 1970s) 
and ligase (which joins two DNA fragments) by Gellert, 
Lehman, Richardson and Hurwitz in the year 1967 were 
discovered.
During this period, scientists also noticed that 
foreign DNA fragments can be taken by bacteria from 
its surrounding environment where it can be integrated 
into its genome. With all this knowledge, scientists asked 
a question that is it possible to transfer the gene of 
interest from one organism to another organism to get its 
product? Stanley Cohen had the expertise in introducing 
plasmid DNA into Escherichia coli (E. coli) and subsequent 
propagation and cloning of plasmids in the bacteria. On 
the contrary, Herbert Boyer had the expertise to cleave 
the double stranded DNA to produce single stranded ends 
with identical termini using restriction enzymes. Both 
visualised the potential of combining the two discoveries 
to what would later become rDNA technology or genetic 
engineering.
Chapter 1 Recombinant DNA Tec.indd   4 23-01-2025   11:18:46
Reprint 2025-26
Page 5


UNIT  I
Recombinant DNA 
Technology
Chapter 1: An Overview of Recombinant DNA Technology
Chapter 2: Host–Vector System
Chapter 3: Gene Cloning
Chapter 4: Application of Recombinant DNA Technology
Chapter 1 Recombinant DNA Tec.indd   1 23-01-2025   11:18:46
Reprint 2025-26
Herbert Wayne ‘Herb’ Boyer (born July 10, 1936) was a researcher 
and entrepreneur in Biotechnology. Herb Boyer hails from 
Derry, Pennsylvania. Boyer went on to graduate at the University 
of Pittsburgh, where he specialised in microbial genetics. After 
preliminary experiments in 1973, the Cohen-Boyer team was able 
to cut open a plasmid loop from one species of bacteria, insert 
a gene from di??erent bacterial species and close the plasmid.  
This created a recombinant—plasmid containing recombined 
DNA from two di??erent sources. The team had created the ??rst 
genetically modi??ed organisms. He is the recipient of the 1990 
National Medal of Science, co-recipient of the 1996 Lemelson–
MIT Prize, and a co-founder of Genentech. He was a professor 
at the University of California, San Francisco (UCSF) and later 
served as the Vice President of Genentech from 1976 until his 
retirement in 1991.
Herbert Boyer
Chapter 1 Recombinant DNA Tec.indd   2 23-01-2025   11:18:46
Reprint 2025-26
1
Chapter 
This chapter gives an overview of recombinant DNA (rDNA) 
technology as to how the application of basic concepts of 
molecular biology, microbiology, genetics, biochemistry, 
etc., led to initial development of rDNA technology. 
Potential application of rDNA technology in the ??eld of 
medicine and agriculture is also discussed in conceptual 
manner along with some noticeable examples of products 
developed through rDNA technology.
1.1 An Overview Of r ec Ombin Ant Dn A 
t echn Ol Ogy In the last century when scientists discovered that 
nucleic acid (DNA) is the principal molecule responsible 
for the expression of characters, attempts were made to 
alter the genetic makeup of an organism by manipulating 
nucleic acid directly. Various methods used for directly 
manipulating nucleic acid/genome of an organism 
are collectively referred to as recombinant DNA (rDNA) 
technology or genetic engineering.
rDNA technology has been possible due to rapid 
progress in various ??elds of biology, which spans from 
An Overview of Recombinant
DNA Technology 
1.1 An Overview of 
Recombinant  
DNA Technology  
Chapter 1 Recombinant DNA Tec.indd   3 23-01-2025   11:18:46
Reprint 2025-26
Biotechnology XII 4
biochemistry, genetics, cytology, microbiology, molecular 
biology and others. Isolation and puri??cation of nucleic 
acids followed by the understanding of their structures, 
properties, functions and ??nally their sequencing in the 
last century are the most important contributions, which 
laid the foundation of development of rDNA technology. 
The ??rst breakthrough in this journey was to establish the 
fact that DNA of an organism not only carries its genetic 
information but also propagates it from one generation 
to another. The next hallmark was the determination of 
chemical and physical structure of DNA molecule and 
double helical structure of DNA. Further, replication, 
transcription and translation of DNA was understood in 
detail by scientists.  Scientists were also able to develop 
various methods and techniques to isolate and purify 
DNA from various organisms. Several enzymes were 
simultaneously discovered using which one can precisely 
manipulate a DNA molecule. Thus, new enzymes, such 
as restriction enzymes (which act as scissors to cut the 
molecules of DNA) by Werner Arbor, Hamilton Smith 
and Daniel Nathan (during late 1960s and early 1970s) 
and ligase (which joins two DNA fragments) by Gellert, 
Lehman, Richardson and Hurwitz in the year 1967 were 
discovered.
During this period, scientists also noticed that 
foreign DNA fragments can be taken by bacteria from 
its surrounding environment where it can be integrated 
into its genome. With all this knowledge, scientists asked 
a question that is it possible to transfer the gene of 
interest from one organism to another organism to get its 
product? Stanley Cohen had the expertise in introducing 
plasmid DNA into Escherichia coli (E. coli) and subsequent 
propagation and cloning of plasmids in the bacteria. On 
the contrary, Herbert Boyer had the expertise to cleave 
the double stranded DNA to produce single stranded ends 
with identical termini using restriction enzymes. Both 
visualised the potential of combining the two discoveries 
to what would later become rDNA technology or genetic 
engineering.
Chapter 1 Recombinant DNA Tec.indd   4 23-01-2025   11:18:46
Reprint 2025-26
Recombinant DNA Technology
5
rDNA technology has immensely contributed in the 
diagnosis and treatment of various diseases including 
genetic disorders and to improve and develop disease free 
high yielding crops. The contribution of rDNA technology 
in shaping our life can be judged from the given examples. 
Earlier several tons of animal pancreatic glands were 
needed to get a few milligrams of insulin to treat diabetes, 
or thousands of animal pituitary glands were required to 
isolate growth hormone to treat dwar??sm. Therefore, these 
products were available in limited quantity as well as at a 
high cost. Nevertheless, such puri??ed therapeutic proteins 
from animal source exhibited immunogenic reactions 
in humans. Needless to say, scientists circumvent the 
above obstacles by producing human insulin and growth 
hormone in bacterial system using rDNA technology. 
Production of interferon to treat cancer, plasminogen 
activator and urokinase to dissolve blood clots are a 
few examples of the contribution of rDNA technology to 
human society.
In the last few decades, by employing rDNA technology, 
scientists have been able to introduce speci??c targeted 
modi??cations in plant genome to get genetically modi??ed 
crops. Thus, in this way, crops have been developed that 
offer resistance to diseases, thereby helping farmers to be 
free from worry about damage of their crops. Similarly, 
drought resistant or salinity tolerant crops were also 
developed so that farmers can grow them in adverse 
environment. Such modi??cations in genetic system of 
plants or crops by rDNA technology not only improve 
the quality of production but also enhance the value of 
products.
Days are not far, when a variety of  important therapeutic 
proteins, peptides and hormones will be produced from 
plants employing rDNA technology. Such products will 
have many advantages over animal-based products in 
terms of costs and contamination. In general, animal-
based products are costlier and require extra care to be 
free of virus and other animal protein contaminants.  
Landmark discoveries that led to the development of 
modern biotechnology (based on rDNA technology is given 
in Box 1).
Box 1
Chapter 1 Recombinant DNA Tec.indd   5 23-01-2025   11:18:46
Reprint 2025-26