Genetic engineering involves directly manipulating an organism's genes. It can be used to remove or insert genes through techniques like recombinant DNA and gene editing. The basics of genetics like genes, genomes, DNA, and chromosomes were discovered in the 1950s-1970s, allowing for genetic manipulation. The first genetically modified organisms were created in the 1970s, including mice and tobacco plants. Genetic engineering has applications in medicine, agriculture, and industry, but also raises ethical concerns. It is a complex field with great potential but also uncertainties.

1. Genetic Engineering
S. Selvajeyanthi
Assistant Professor of
Microbiology

3. Basics
A gene is the basic physical and functional unit of heredity.
A genome is the complete set of genetic information in an organism
DNA molecule is packaged into thread-like structures called
chromosomes.
A plasmid is a small, circular, double-stranded DNA molecule that is distinct
from a cell's chromosomal DNA.
Enzymes are proteins that act as biological catalysts (biocatalysts). Catalysts
accelerate chemical reactions. It catalyze more than 5,000 biochemical reaction.
Alleles are variants of the same gene that occur on the same place on a
chromosome
A locus refers to the location on the chromosome where the gene is found.

4. Definition
“A technique used to insert or delete a mutant gene or to manipulate
a genome of an organism is known as genetic engineering
Genetic engineering, also called genetic modification or genetic
manipulation, is the direct manipulation of an organism's genes using the
genome.
Genetic engineering, the artificial manipulation, modification, and
recombination of DNA or other nucleic acid molecules in order to modify
an organism or population of organisms.
The process can be used to remove, or "knock out", genes. The new DNA
can be inserted randomly, or targeted to a specific part of the genome.

5. History of Genetic Engineering
The study of genetics dates back to 1865, when an Austrian monk named
Gregor Mendel published his studies of inheritance in pea plants. In the
past 20th century, scientists decided to study his laws of heredity
evolution and selective breeding.
DNA molecule structures work and how they stored and transmitted
genetic information was discovered in 1953 by James Watson, Francis
Crick, and Maurice Wilkins.
Throughout the 1950’s to the 1970’s, chemical tools were discovered and
technology that enabled the alternation of DNA .
In 1977, it was discovered that a germ called bacterium can be used to put
genes into the DNA of plant cells. Later on, other methods soon became
invented to change DNA.

6. The term genetic engineering was first used by the science-fiction
novelist, not by any scientist. In the year, 1951, Jack Williamson used the
term“genetic engineering” for the first time in his novel “Dragon’s
island”.
The first recombinant DNA was constructed by Paul Berg in 1972.
In the same year, Herbert Boyer and Stanley Cohen performed gene
transfer experiments.
In 1974, Rudolf Jaenisch had created genetically modified mice, the first
time in the history of genetics.
After the success of Rudolf, the genetically modified or genetically
engineered tobacco plant species was developed in 1976

7. Type of genetic engineering techniques
Recombinant DNA- A recombinant DNA technology is a type
of genetic engineering technology in which an artificial DNA
molecule is constructed by ligating two different DNAs using
physical methods. For that, the gene of interest is inserted
into the plasmid vector and used for gene transfer
experiments.
Gene delivering- Gene delivering technique is employed for
the insertion of a gene of interest into the host genome.

8. Electrophoration, solicitation and viral vector-mediated gene
transfer, liposome-mediated gene transfer, transposon-
mediated gene transfer are some of the methods used for
that.
Gene editing- A gene-editing technique is used to edit the
genome in which an undesired DNA sequence is removed or
a new gene can be inserted into the host genome. CRISPR-
CAS9, TALEN and ZFN are some known gene-editing tools
used in gene therapy experiments.

9. Molecular tools in Genetic Engineering
Nucleases-
Restriction enzymes
DNA ligase
Polymerase

10. Process of genetic engineering:
The genetic engineering technique is used for many different
purposes thus we must have to decide first the purpose of the
experiment. The entire process of genetic engineering can be divided
into 5 broader steps:
● Selecting and isolating the candidate gene
● Selection and construction of plasmid
● Gene transformation
● Insertion of DNA into the host genome
● Confirmation of insert

13. Applications of Genetic Manipulation :
Genetic engineering has great industrial and agricultural value. It is practiced
in medicine, genetic research, agriculture, crop improvement, and for
production of therapeutic drugs.
The recombinant DNA technology is used in the crop improvement and
development of new economically important traits. Some of them are:
● Herbicide resistance
● Virus resistance
● Delayed fruit ripening
● Altered oil content
● Pollen control
● Development of cold and drought-tolerant plant species.

15. Limitations of genetic engineering:
There are ethical issues associated with the use of gene
therapy and genetically engineered products.
Also, to provide an economic value to the food product or
any GM product, the nutritional values are compromised.
Because of the adverse effect of it, new resistant
pathogenic strains are evolved faster.

16. Also, the side effects of gene therapy and the use of viruses in it
are harmful to the target organism.
Genetically modified food and plant products are always becoming
a center of controversy.
The technology is costlier as gene therapy cost up to 50,000 USD.
In 2011, Congress enacted a federal law that prevents U.S. patents
from being issued on human embryos, including any that have
been genetically modified.But in 2018, Chinese scientist Dr. He
Jiankui has claimed to have helped created the world’s first
genetically-modified babies. Which has led humans and scientists
all over the world to question if genetically modifying would
change everything in society forever in the future.

17. The group of enzymes used in rDNA technology which cleave or cut the genetic
material ……..
a). Nucleases b). RNaseP
c). Reverse transcriptase d). All the above
DNA ligase isolated from and is widely used.
a). E. coli b). T 4 bacteriophage
c). Both a and b d). None of the above
The enzymes used in rDNA technology includes ……..
a). Nucleases b). Restriction enzymes
c). DNA ligase d).All the above

18. Source :
https://geneticeducation.co.in/what-is-genetic-engineering-definition-types-
process-and-application/
Sources:
National Research Council (US) Committee on Identifying and Assessing
Unintended Effects of Genetically Engineered Foods on Human Health. Safety of
Genetically Engineered Foods: Approaches to Assessing Unintended Health
Effects. Washington (DC): National Academies Press (US); 2004. 2, Methods and
Mechanisms for Genetic Manipulation of Plants, Animals, and Microorganisms.
Wallace RB. Principles of gene manipulation. An introduction to genetic
engineering. Studies in microbiology. Am J Hum Genet. 1981;33(4):652-653.

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