Release date : 23rd July, 2020 Word-count : approx. 724
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ZoologyOption 2020
Release date : 23rd July, 2020
Word-count : approx. 724
TRANSGENICS - Biotechnology
For thousands of years, we have used breeding methods to modify organisms.
Corn, cattle, and even dogs have been selectively bred over generations to have
certain desired traits. Today we have a full-fledged discipline in
BIOTECHNOLOGY called TRANSGENICS - transgene - a gene that has been
transferred naturally, or by any of a number of genetic engineering techniques from
one organism to another. The introduction of a transgene (transgenesis) has the
potential to change the phenotype of an organism. Genetically modified organisms
(GMOs) are living organisms whose genetic material has been artificially
manipulated in a laboratory through genetic engineering. This creates
combinations of plant, animal, bacteria, and virus genes that do not occur in nature
or through traditional crossbreeding methods. A GMO is an animal, plant, or
microbe whose DNA has been altered using genetic engineering techniques.
In 1974 Rudolf Jaenisch created a transgenic mouse by introducing foreign DNA
into its embryo, making it the world's first transgenic animal. However it took
another eight years before transgenic mice were developed that passed the
transgene to their offspring.
More than 90% of all soybean cotton and corn acreage in the U.S. is used to grow
genetically engineered crops. Other popular and approved food crops include sugar
beets, alfalfa, canola, papaya and summer squash. More recently, apples that don't
brown and bruise-free potatoes were also approved by the FDA. Broccoli, for
example, is not a naturally occurring plant. It’s been bred from undomesticated
Brassica oleracea or ‘wild cabbage’; domesticated varieties of B. oleracea include
both broccoli and cauliflower. Broccoli, along with any seedless variety of fruit
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(including what you think of as bananas), and most of the crops grown on farms
today would not exist without human intervention.
Not all GMO plants are created equally : it’s the trait, not the production method,
that’s important
The possible benefits of genetic engineering include :
More nutritious food.
Tastier food.
Disease- and drought-resistant plants that require fewer environmental resources
(such as water and fertilizer)
Less use of pesticides.
Increased supply of food with reduced cost and longer shelf life.
Faster growing plants and animals.
In the early 1980s, the plant biotechnology era began with Agrobacterium
tumifaciens. This bacterium naturally infects plants and, in the wild, creates
tumors by transferring DNA between itself and the plant it has infected.
Scientists use this natural property to transfer genes to plant cells from an A.
tumifaciens bacterium modified to contain a gene of interest.
Transgenic Animals are of application in Agriculture. The production of
transgenic livestock has the opportunity to significantly improve human
health, enhance nutrition, protect the environment, increase animal welfare,
and decrease livestock disease.
Transgenic animals can also be created by inserting DNA into embryonic stem
cells which are then micro-injected into an embryo which has developed for five or
six days after fertilization, or infecting an embryo with viruses that carry a DNA of
interest.
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The production of transgenic livestock has the opportunity to significantly improve
human health, enhance nutrition, protect the environment, increase animal welfare,
and decrease livestock disease.
Transgenic animals can provide animal models of human disease to help
researchers find new treatments. Usually, small transgenic animals, such as mice or
rats, are used for this type of research. Milk composition can be altered to make a
functional food.
The Methods Used to Create Transgenic Animals
The most common method is through DNA microinjection. This is the process of
taking the DNA of a different or same species and injecting it into the pronucleus
of a fertilized ovum. Inserting the DNA is random and there is a high chance that
injected gene will not insert itself into a site on the host DNA that will permit it’s
expression.
Retrovirus-meditated gene transfer involves using retroviruses as vectors, an
organism that transfers a disease from one animal to the genetic materials or a cell,
to another. A retrovirus is a single-stranded positive-sense RNA virus with a DNA
intermediate and, as an obligate parasite, targets a host cell. Offspring from this
method are chimeric, and not all cells carry the retrovirus.
Embryonic stem-cell mediated gene transfer involves prior insertion of the desired
DNA into totipotent stem cells from the embryo (stem cells that can develop into
any type of specialised cell). This method results in a chimeric animal; animals that
are produced by the merging of multiple fertilised eggs.
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