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Animals whose genomes have been modified are known as Transgenic Animals. A foreign gene is inserted into the original genome of the animal to change its DNA. This method is used to improve the genetic traits of the targeted animal. The first ever transgenic animal was chimeric Mice, they were created by combining two cells taken from two different embryos of different strains.
In the starting phases, genetic improvement was done by selective breeding methods. In which, the animals having required genetic qualities were mated for producing Individuals with Improved genetic characteristics. This method was quite successful, but was later replaced by recombinant DNA technology due to higher time consumption and higher expenses.
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| Table of Content |
Key Terms: Genomes, Transgenic animals, DNA, Calcium phosphate, Viruses, Gene, Transgene
Define Transgenic Animals
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The process of production of transgenic animals is known as Transgenesis. In which a foreign gene with desired qualities is introduced into the genetics of the targeted animal. The foreign gene introduced is known as the Transgene, and the Animal whose genome is changed is known as Transgenic. The genes are then passed further on to the next generations.
Specifically designed transgenic animals are used to study the effects of genes on normal functioning of the human body & its development. They are also used to understand how gene contribute to the development of a disease and then help in treatments of various diseases. Transgenic animals are also used to produce expensive biological products at cheaper rates.Transgenic animals are genetically modified, that is why they are also known as Genetically Modified Animals (Organisms).
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Methods For Producing Transgenic Animals
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The Transgenic Animals are created by the various methods explained below:
Physical Transfection
In the Physical Transfection method, the Gene of desired characteristics is directly injected into the pronucleus of the Fertilised Ovum. This was the first method to become effective in Mammals and was applicable to a large variety of species. Some other methods of Physical Transfection are particle bombardment, ultrasound & electroporation.
Chemical Transfection
One of the Chemical processes of gene Transfection is Transformation. In this method, DNA of the targeted animal is taken up in presence of Calcium Phosphate. In this method, the DNA & calcium phosphate co-precipitates, which eases in DNA uptake. The mammalian cells have the ability to take up foreign DNA from the culture medium.
Retrovirus-Mediated Gene Transfer
In order to enhance the chances of expression, the genes are conveyed by means of a vector. As retroviruses are capable of infecting the host cell, they are used as vectors so that they can transfect the desired genes into the targeted animal's genome.
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Viral Vectors
In this method, various viruses are used to transfect rDNA into the Animal cell. The viruses have the ability to infect the Host Cell, express well as well as replicate systematically.
Bactofection
Bactofection is the method by which genes of interest are transferred into the genome of the targeted animal with the help of bacteria.
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| Important Topics related to Transgenic Animals | ||
|---|---|---|
| Genetically modified organisms | Applications of Enzymes | Gene therapy |
| Plasmid Definition | RNA Interference | GEAC |
Some Transgenic Animals
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Some examples of Transgenic Animals are as follows,
Transgenic Mice
The process wherein by injecting DNA into oocytes or 1-2, the transgenic mice are developed is called Embryos taken from Female Mice. After injecting the DNA, the Embryo is implanted into the uterus of Receptive Females.
Dolly Sheep
Dolly, the sheep was the very first mammal to be cloned with the help of an adult cell. In this process, the udder cells from a Finn Dorset white sheep of 6 years old were injected into an unfertilized egg from a Scottish Blackface ewe, whose nucleus was removed. With the help of electrical pulses, the cell was made to fuse. After fusion of the cell nucleus with the egg, the resulting embryo was cultured for the next 6-7 days. The embryo was then implanted into another Scottish Blackface Ewe, which was responsible for the birth of Transgenic Sheep, Dolly.
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| Chapter Related Topics | ||
|---|---|---|
| Difference Between Gene and DNA | Biotechnology Agriculture | Bioremediation |
| Biotechnology mcqs | Genetically Modified Organisms | DNA Cloning |
Some Applications of Transgenic Animals
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It is because the benefits are provided to the man that the Transgenic Animals are being created. Some of them are given below:
Biological Products
Various biological products such as Medicines & Nutritional Supplements are obtained from transgenic animals. Research is still going on for manufacturing medicines in order to treat the diseases like hereditary emphysema and phenylketonuria. The first Transgenic Cow, produced milk which contained 2.4 gram human protein per litre. This milk can also be given to babies as a substitute of natural cow milk.
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Normal Physiology and Development
Foreign Genes are introduced into Transgenic Animals, due to which the growth factor alteres. Which is why these animals are helpful for the study of Gene Regulation and their effects on the Functioning of the Body.
Study About Diseases
These animals are specially structured for the analysis of the role of genes in the development of certain diseases. Additionally, in order to come up with a cure for these diseases, the transgenic animals are used as model organisms.
For instance, there are various Transgenic models for diseases such as Alzheimer's and Cancer.
Vaccine Safety
Before the vaccines are injected into humans, the transgenic animals are used as model organisms. This is for testing the safety of the vaccines.
Previous Years Questions
- Some of the steps involved in the production of Humulin are...[KCET 2010]
- Genetic engineered male sterile crop plants may….[KEAM 2015]
- Plasmid has been used as vector because...[NEET 2000]
- Production of human protein in bacteria by genetic...[NEET 2005]
- The crops engineered for glyphosate are...[NEET 2015]
- The process of RNA interference has been..[NEET 2011]
- The transgenic animals are those which have...[NEET 1995]
- Genetically engineered bacteria have been...[NEET 1996]
- In RNA, genes are silenced using...[NEET 2019]
- Golden Rice is a promising transgenic crop..[NEET 2006]
- A transgenic food crop which may help in...[NEET 2008]
- Bt cotton variety that was developed by..[NEET 2020]
- Bacillus thuringiensis forms protein crystals...[NEET 2011]
- Cry endotoxins obtained from Bacillus...[NEET 2008]
- ELISA is used to detect viruses where...[NEET 2004]
- Genetic engineering has been..[NEET 2010]
Sample Questions
Ques. Can the Transgenic Animals created in labs be released into the Ecosystem? (1 mark)
Ans. No , because if they are released into the Ecosystem they can spread to the natural population and cause an imbalance in the Ecosystem.
Ques. How does a transgenic cow differ from a Normal/Natural cow? (1 mark)
Ans. Transgenic cows are the genetically modified (GM) cows. An extra gene or genes gets inserted into their DNA. That Extra Gene may come from the different species or from the same species .
Ques. Are knockout mice also a Example of transgenic Animals? (1 mark)
Ans. Yes, they are also Genetically Modified Mouse in which an existing gene has been Inactivated by replacing it with an artificial piece of DNA.
Ques. What was the unique Application of the milk obtained from the first transgenic cow ? (1 mark)
Ans. The First ever transgenic cow (Rosie) gave milk which had human alpha-lactalbumin. It was a more balanced product nutritionally for human babies than milk of a natural cow.
Ques. What are the Ethical Issues of Transgenic Animals ? (1 mark)
Ans. Genetic Engineering and selective breeding violate the animal rights as they involve manipulating animals .In this the animals are used for the Wellbeing of Humans.Rather than treating them being of value in themselves .
Ques. What are the methods of creating transgenic animals? (4 marks)
Ans. The methods of creating transgenic animals are,
Physical transfection- In the Physical Transfection method, the Gene of desired characteristics is directly injected into the pronucleus of the Fertilised Ovum. This was the first method to become effective in Mammals and was applicable to a large variety of species.
Chemical transfection- One of the Chemical processes of gene Transfection is Transformation. In this method, DNA of the targeted animal is taken up in presence of Calcium Phosphate. In this method, the DNA & calcium phosphate co-precipitates, which eases in DNA uptake.
Retrovirus-mediated gene transfer- In order to enhance the chances of expression, the genes are conveyed by means of a vector. As retroviruses are capable of infecting the host cell, they are used as vectors so that they can transfect the desired genes into the targeted animal's genome.
Viral vectors- In this method, various viruses are used to transfect rDNA into the Animal cell. The viruses have the ability to infect the Host Cell, express well as well as replicate systematically.
Bactofection- Bactofection is the method by which genes of interest are transferred into the genome of the targeted animal with the help of bacteria.
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