Toka Mohamed El_Sayed _ 2D

Research paper

A Comparison Between the Genetically

Modified Organisms and the Theory of
Evolution Over Time
Toka Mohamed El_Sayed Radwan
(Maadi STEM School for
Girls )
1. genetically modified organism (GMO)
Abstract
A genetically modified organism (GMO) is an animal, plant, or microbe whose
DNA has been altered using genetic engineering techniques. For thousands of
years, humans have used breeding methods to modify organisms. Corn, cattle, and
even dogs have been selectively bred over generations to have certain desired
traits. Within the last few decades, however, modern advances in biotechnology
have allowed scientists to directly modify the DNA of microorganisms, crops, and
animals. Conventional methods of modifying plants and animals—selective
breeding and crossbreeding—can take a long time. Moreover, selective breeding
and crossbreeding often produce mixed results, with unwanted traits appearing
alongside desired characteristics. The specific targeted modification of DNA using
biotechnology has allowed scientists to avoid this problem and improve the genetic
makeup of an organism without unwanted characteristics tagging along. Most
animals that are GMOs are produced for use in laboratory research. These
animals are used as “models” to study the function of specific genes and, typically,
how the genes relate to health and disease. Some GMO animals, however, are
produced for human consumption. Salmon, for example, has been genetically
engineered to mature faster, and the U.S. Food and Drug Administration has stated
that these fish are safe to eat. MOs are perhaps most visible in the produce section.
The first genetically engineered plants to be produced for human consumption
were introduced in the mid-1990s. Today, approximately 90 percent of the corn,
soybeans, and sugar beets on the market are GMOs. Genetically engineered crops
produce higher yields, have a longer shelf life, are resistant to diseases and pests,
and even taste better. These benefits are a plus for both farmers and consumers.
For example, higher yields and longer shelf life may lead to lower prices for
consumers, and pest-resistant crops means that farmers don’t need to buy and use
as many pesticides to grow quality crops. GMO crops can thus be kinder to the
environment than conventionally grown crops. Genetically modified foods do cause
controversy, however. Genetic engineering typically changes an organism in a way

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that would not occur naturally. It is even common for scientists to insert genes into
an organism from an entirely different organism. This raises the possible risk of
unexpected allergic reactions to some GMO foods. Other concerns include the
possibility of the genetically engineered foreign DNA spreading to non-GMO
plants and animals. So far, none of the GMOs approved for consumption have
caused any of these problems, and GMO food sources are subject to regulations
and rigorous safety assessments. In the future, GMOs are likely to continue playing
an important role in biomedical research. GMO foods may provide better nutrition
and perhaps even be engineered to contain medicinal compounds to enhance
human health. If GMOs can be shown to be both safe and healthful, consumer
resistance to these products will most likely diminish.

Introduction
Organisms with changes introduced in DNA are Genetically modified organisms. It
is the best way of producing desired organisms. Genetically Modified food is
mostly antibiotic resistant, nutritionally enhanced, herbicide resistant and disease
resistant. In 1990’s first GM

Benefits of GM Food. Food was produced. Celgene was the scientist who produced
first GM tomato and named it ‘Farar.’ Flavor Savr has a gene to delay softening of
fruit. In the beginning it was available only in the Europe and the America. But now
we can get GM tomatoes from anywhere across the world. Currently, rice, wheat,
corn, cotton, canola and soy beans are produced. Golden rice are GM they have high
content of vitamin A and iron. GM wheat has high level of zinc and iron. GM
bananas produce a vaccine, which is helpful in treating hepatitis B. In this research
paper I will talk about the benefits and different ways by which GM products are
produced. Their advantages in different areas of life. The thesis statement is ‘ GM
food do not have harmful effects on human health.’ The methodology I used is survey
and interviews for this research.

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Mechanisms for Genetic Manipulation of Plants, Animals,
and Microorganisms
Plants genetic modifications
• Simple Selection
The easiest method of plant genetic modification (see Operational
Definitions in Chapter 1), used by our nomadic ancestors and continuing
today, is simple selection. That is, a genetically heterogeneous population of
plants is inspected, and “superior” individuals—plants with the most desired
traits, such as improved palatability and yield—are selected for continued
propagation. The others are eaten or discarded. The seeds from the superior
plants are sown to produce a new generation of plants, all or most of which
will carry and express the desired traits. Over a period of several years, these
plants or their seeds are saved and replanted, which increases the population
of superior plants and shifts the genetic population so that it is dominated by
the superior genotype. This very old method of breeding has been enhanced
with modern technology.
An example of modern methods of simple selection is marker-assisted
selection, which uses molecular analysis to detect plants likely to express
desired features, such as disease resistance to one or more specific pathogens
in a population. Successfully applying marker-assisted selection allows a
faster, more efficient mechanism for identifying candidate individuals that
may have “superior traits.”
Superior traits are those considered beneficial to humans, as well as to
domesticated animals that consume a plant-based diet; they are not
necessarily beneficial to the plant in an ecological or evolutionary context.
Often traits considered beneficial to breeders are detrimental to the plant
from the standpoint of environmental fitness. For example, the reduction of
unpalatable chemicals in a plant makes it more appealing to human
consumers but may also attract more feeding by insects and other pests,
making it less likely to survive in an unmanaged environment. As a result,
cultivated crop varieties rarely establish populations in the wild when they

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 escape from the farm. Conversely, some traits that enhance a plant's
resistance to disease may also be harmful to humans.
• Crossing
Crossing occurs when a plant breeder takes pollen from one plant and
brushes it onto the pistil of a sexually compatible plant, producing a hybrid
that carries genes from both parents. When the hybrid progeny reaches
flowering maturity, it also may be used as a parent.
Plant breeders usually want to combine the useful features of two plants. For
example, they might add a disease-resistance gene from one plant to another
that is high-yielding but disease-susceptible, while leaving behind any
undesirable genetic traits of the disease-resistant plant, such as poor fertility
and seed yield, susceptibility to insects or other diseases, or the production
of antinutritional metabolites.
Because of the random nature of recombining genes and traits in crossed
plants, breeders usually have to make hundreds or thousands of hybrid
progeny to create and identify those few that possess useful features with a
minimum of undesirable features. For example, the majority of progeny may
show the desired disease resistance, but unwanted genetic features of the
disease-resistant parent may also be present in some. Crossing is still the
mainstay of modern plant breeding, but many other techniques have been
added to the breeders' tool kit.
• Interspecies Crossing
Interspecies crossing can take place through various means. Closely related
species, such as cultivated oat (Avena sativa) and its weedy relative wild oat
(Avena fatua), may cross-pollinate for exchange of genetic information,
although this is not generally the case. Genes from one species also can
naturally integrate into the genomes of more distant relatives under certain
conditions. Some food plants can carry genes that originate in different
species, transferred both by nature and by human intervention. For example,
common wheat varieties carry genes from rye. A common potato, Solanum
tuberosum, can cross with relatives of other species, such as S. aciculae
(Kosuke et al., 1999) or S. chaconnes (Sanford et al., 1998; Zimnoch-
Guzowska et al., 2000).

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 Chromosome engineering is the term given to nonrecombinant
deoxyribonucleic acid (rDNA) cytogenetic manipulations, in which portions
of chromosomes from near or distant species are recombined through a
natural process called chromosomal translocation. Sears (1956, 1981)
pioneered the human exploitation of this process, which proved valuable for
transferring traits that were otherwise unattainable, such as pest or disease
resistance, into crop species. However, because transferring large segments
of chromosomes also transferred a number of neutral or detrimental genes,
the utility of this technique was limited.
Recent refinements allow plant breeders to restrict the transferred genetic
material, focusing more on the gene of interest (Lukaszewski, 2004). As a
result, chromosome engineering is becoming more competitive with rDNA
technology in its ability to transfer relatively small pieces of DNA. Several
crop species, such as corn, soybean, rice, barley, and potato, have been
improved using chromosome engineering (Gupta and Tsuchiya, 1991).
• Embryo Rescue
Sometimes human technical intervention is required to complete an
interspecies gene transfer. Some plants will cross-pollinate and the resulting
fertilized hybrid embryo develops but is unable to mature and sprout.
Modern plant breeders work around this problem by pollinating naturally
and then removing the plant embryo before it stops growing, placing it in a
tissue-culture environment where it can complete its development. Such
embryo rescue is not considered genetic engineering, and it is not commonly
used to derive new varieties directly, but it is used instead as an intermediary
step in transferring genes from distant, sexually incompatible relatives
through intermediate, partially compatible relatives of both the donor and
recipient species.
• Somatic Hybridization
Recent advances in tissue-culture technologies have provided new
opportunities for recombining genes from different plant sources. In somatic
hybridization, a process also known as cell fusion, cells growing in a culture
medium are stripped of their protective walls, usually using pectinase,
cellulase, and hemicellulase enzymes. These stripped cells, called
protoplasts, are pooled from different sources and, through the use of varied
techniques such as electrical shock, are fused with one another.
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 When two protoplasts fuse, the resulting somatic hybrid contains the genetic
material from both plant sources. This method overcomes physical barriers
to pollen-based hybridization, but not basic chromosomal incompatibilities.
If the somatic hybrid is compatible and healthy, it may grow a new cell wall,
begin mitotic divisions, and ultimately grow into a hybrid plant that carries
genetic features of both parents. While protoplast fusions are easily
accomplished, as almost all plants (and animals) have cells suitable for this
process, relatively few are capable of regenerating a whole organism, and
fewer still are capable of sexual reproduction. This non-genetic engineering
technique is not common in plant breeding as the resulting range of
successful, fertile hybrids has not extended much beyond what is possible
using other conventional technologies.
• Soma clonal Variation
Soma clonal variation is the name given to spontaneous mutations that occur
when plant cells are grown in vitro. For many years plants regenerated from
tis-sue culture sometimes had novel features. It was not until the 1980s that
two Australian scientists thought this phenomenon might provide a new
source of genetic variability, and that some of the variant plants might carry
attributes of value to plant breeders (Larkin and Scowcroft, 1981).
Through the 1980s plant breeders around the world grew plants in vitro and
scored regenerants for potentially valuable variants in a range of different
crops. New varieties of several crops, such as flax, were developed and
commercially released (Rowland et al., 2002). Molecular analyses of these
new varieties were not required by regulators at that time, nor were they
conducted by developers to ascertain the nature of the underlying genetic
changes driving the variant features. Soma clonal variation is still used by
some breeders, particularly in developing countries, but this non-genetic
engineering technique has largely been supplanted by more predictable
genetic engineering technologies.
• Mutation Breeding
Induced Chemical and X-ray Mutagenesis
Mutation breeding involves exposing plants or seeds to mutagenic agents
(e.g., ionizing radiation) or chemical mutagens (e.g., ethyl methane
sulfonate) to induce random changes in the DNA sequence. The breeder can

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 adjust the dose of the mutagen so that it is enough to result in some
mutations, but not enough to be lethal. Typically a large number of plants or
seeds are mutagenized, grown to reproductive maturity, and progeny are
derived. The progeny are assessed for phenotypic expression of potentially
valuable new traits.
As with soma clonal variation, the vast majority of mutations resulting from
this technique are deleterious, and only chance determines if any genetic
changes useful to humans will appear. Other than through varying the
dosage, there is no means to control the effects of the mutagen or to target
particular genes or traits. The mutagenic effects appear to be random
throughout the genome and, even if a useful mutation occurs in a particular
plant, deleterious mutations also will likely occur. Once a useful mutation is
identified, breeders work to reduce the deleterious mutations or other
undesirable features of the mutated plant. Nevertheless, crops derived from
mutation breeding still are likely to carry DNA alterations beyond the
specific mutation that provided the superior trait.
Induced-mutation crops in most countries (including the United States) are
not regulated for food or environmental safety, and breeders generally do not
conduct molecular genetic analyses on such crops to characterize the
mutations or determine their extent. Consequently, it is almost certain that
mutations other than those resulting in identified useful traits also occur and
may not be obvious, remaining uncharacterized with unknown effects.
• Worldwide, more than 2,300 different crop varieties have been developed
using induced mutagenesis (FAO/IAEA, 2001), and about half of these have
been developed during the past 15 years. In the United States, crop varieties
ranging from wheat to grapefruit have been mutated since the technique was
first used in the 1920s. There are no records of the molecular
characterizations of these mutant crops and, in most cases, no records to
retrace their subsequent use.
• Cell Selection
Several commercial crop varieties have been developed using cell selection,
including varieties of soybeans (Sebastian and Chaleff, 1987), canola
(Swanson et al., 1988), and flax (Rowland et al., 1989). This process
involves isolating a population of cells from a so-called “elite plant” with

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 superior agricultural characteristics. The cells are then excised and grown
in culture. Initially the population is genetically homogeneous, but changes
can occur spontaneously (as in soma clonal variation) or be induced using
mutagenic agents. Cells with a desired phenotypic variation may be selected
and regenerated into a whole plant. For example, adding a suitable amount
of the appropriate herbicide to the culture medium may identify cells
expressing a novel variant phenotype of herbicide resistance. In theory, all
of the normal, susceptible cells will succumb to the herbicide, but a newly
resistant cell will survive and perhaps even continue to grow. An herbicide-
resistant cell and its derived progeny cell line thus can be selected and
regenerated into a whole plant, which is then tested to ensure that the
phenotypic trait is stable and results from a heritable genetic alteration. In
practice, many factors influence the success of the selection procedure, and
the desired trait must have a biochemical basis that lends itself to selection
in vitro and at a cellular level.
Breeders cannot select for increased yield in cell cultures because the
cellular mechanism for this trait is not known. The advantage of cell
selection over conventional breeding is the ability to inexpensively screen
large numbers of cells in a petri dish in a short time instead of breeding a
similar number of plants in an expensive, large field trial conducted over an
entire growing season.
Like soma clonal variation, cell selection has largely been superseded by
recombinant technologies because of their greater precision, higher rates of
success, and fewer undocumented mutations.
• Genetic Engineering
As noted in Chapter 1, this report defines genetic engineering specifically as
one type of genetic modification that involves an intended targeted change in
a plant or animal gene sequence to effect a specific result through the use of
rDNA technology. A variety of genetic engineering techniques are described
in the following text.
• Microbial Vectors
Agrobacterium tumefaciens is a naturally occurring soil microbe best known
for causing crown gall disease on susceptible plant species. It is an unusual
pathogen because when it infects a host, it transfers a portion of its own

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 DNA into the plant cell. The transferred DNA is stably integrated into the
plant DNA, and the plant then reads and expresses the transferred genes as
if they were its own. The transferred genes direct the production of several
substances that mediate the development of a crown gall.
Among these substances is one or more unusual nonprotein amino acids,
called opines. Opines are translocated throughout the plant, so food
developed from crown gall-infected plants will carry these opines. In the
early 1980s strains of Agrobacterium were developed that lacked the
disease-causing genes but maintained the ability to attach to susceptible
plant cells and transfer DNA.
By substituting the DNA of interest for the crown gall disease-causing DNA,
scientists derived new strains of Agrobacterium that deliver and stably
integrate specific new genetic material into the cells of target plant species.
If the transformed cell then is regenerated into a whole fertile plant, all cells
in the progeny also carry and may express the inserted genes.
Agrobacterium is a naturally occurring genetic engineering agent and is
responsible for the majority of GE plants in commercial production.
• Microprojectile Bombardment
Klein and colleagues (1987) discovered that naked DNA could be delivered
to plant cells by “shooting” them with microscopic pellets to which DNA
had been adhered. This is a crude but effective physical method of DNA
delivery, especially in species such as corn, rice, and other cereal grains,
which Agrobacterium does not naturally transform. Many GE plants in
commercial production were initially transformed using microprojectile
delivery.
• Electroporation
In electroporation, plant protoplasts take up macromolecules from their
surrounding fluid, facilitated by an electrical impulse. Cells growing in a
culture medium are stripped of their protective walls, resulting in
protoplasts. Supplying known DNA to the protoplast culture medium and
then applying the electrical pulse temporarily destabilizes the cell
membrane, allowing the DNA to enter the cell. Transformed cells can then
regenerate their cell walls and grow to whole, fertile transgenic plants.

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 Electroporation is limited by the poor efficiency of most plant species to
regenerate from protoplasts.
• Microinjection
DNA can be injected directly into anchored cells. Some proportion of these
cells will survive and integrate the injected DNA. However, the process is
labor intensive and inefficient compared with other methods.
• Transposons/Transposable Elements
The genes of most plant and some animal (e.g., insects and fish) species
carry transposons, which are short, naturally occurring pieces of DNA with
the ability to move from one location to another in the genome. Barbara
McClintock first described such transposable elements in corn plants during
the 1950s (Cold Spring Harbor Laboratory, 1951). Transposons have been
investigated extensively in research laboratories, especially to study
mutagenesis and the mechanics of DNA recombination. However, they have
not yet been harnessed to deliver novel genetic information to improve
commercial crops.
Nontrans genic Molecular Methods of Manipulation
Genetic features can be added to plants and animals without inserting them
into the recipient organism's native genome. DNA of interest may be
delivered to a plant cell, expressing a new protein—and thereby a new
trait—without becoming integrated into the host-cell DNA. For example,
virus strains may be modified to carry genetic material into a plant cell,
replicate, and thrive without integrating into the host genome. Without
integration, however, new genetic material may be lost during meiosis, so
that seed progeny may not carry or express the new trait. Many food plants
are perennials or are propagated by vegetative means, such as grafting or
from cuttings. In these cases the virus and new genes would be maintained in
subsequent, non sexually generated populations. Technically such plants are
not products of rDNA because there is no recombination or insertion of
introduced DNA into the host genome. Although these plants are not GE,
they do carry new DNA and new traits. No such products are known to be
currently on the market in the United States or elsewhere. (See McHugh
[2000] for further information on genetic mechanisms used in plant
improvement.)

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• Genetic modification for animals
• Domestication and Artificial Selection
• Modern breeds of livestock differ markedly from their ancestors as a result
of breeding strategies. For example, milk production per cow has increased
among Holstein dairy cattle. Similarly, breeding programs have resulted in
lean, fast-growing pigs (Notter, 1999). Chickens from modern breeds each
produce more than 250 eggs per year, approximately double that produced in
1950, again mainly due to genetic selection.
• Established and emerging biotechnologies in animal agriculture include
assisted reproductive technologies; use of naturally occurring hormones,
such as recombinant bovine somatotropin; marker-assisted selection;
biotechnologies to enhance reproductive efficiency without affecting the
genome; and biotechnologies to enhance expression of desirable genes.
• Assisted Reproductive Procedures
Modern breeds of livestock differ from their ancestors because the use of
frozen semen for artificial insemination (AI), along with sire testing and sire
selection, has markedly affected the genetic quality of livestock, especially
dairy cattle. Select bulls are tested for fertility and judged on the basis of the
milk that their daughters produce. A notable example is the milk from
Holstein cows, which increased almost threefold between 1945 and 1995
(Majeskie, 1996) through a combination of AI using semen from select bulls
and improved milk production management (Diamond, 1999; Hale, 1969).
Using sophisticated statistical models to predict breeding values, sire testing
and selection, crossbreeding, and marker-assisted selection, along with AI,
have greatly advanced the production characteristics of livestock. It is
expected that AI will continue to be an integral tool in animal production
systems.
(Assisted reproductive and recombinant hormone technologies are discussed
in detail in the accompanying sub report, Methods and Mechanisms of
Genetic Manipulation and Cloning of Animals.)
Techniques Fundamental to Genetic Engineering in Livestock
Although the following are not methods to generate modifications per se,
they are considered modern methods that support the overall breeding and

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 selection system for propagating desired genotypes for animals expressing
desired traits.
• Embryo Recovery and Transfer and Superovulation
Embryo recovery and transfer allow valuable animals to contribute more
offspring to the gene pool (Seidel, 1984). Embryos that are frozen and stored
before being used to initiate a pregnancy result in 40,000 to 50,000 beef
calves per year (NAAB, 2000). Emerging technologies will allow the sexing
of semen and embryos to control the gender of the offspring. The production
of single-sex sperm, by cell sorting X and Y sperm, will greatly benefit the
livestock industries (Johnson, 2000).
• In Vitro Maturation and Fertilization of Oocytes
Up to several thousand embryos can be produced using techniques for
recovering and maturing immature eggs, or oocytes, in about one day in a
medium containing hormones, and then fertilizing them with live sperm or
injecting a single sperm or sperm head into their outer layers—either
beneath the zona pellucida or directly into the cytoplasm. The resulting
zygotes are cultured in vitro, usually to the blastocyst stage, before being
transferred to recipient females (First, 1991). The commercial application of
in vitro maturation and fertilization has resulted in as many as 4,000 calves
being born in a single year (NAAB, 2000).
• Embryo Splitting
Splitting or bisecting embryos yields zygotic twins, or non-GE clones, that
are genetically identical in both their nuclear and mitochondrial genes
(Heyman et al., 1998). Maternal twins exhibit greater variation in phenotype
than paternal twins with only one X chromosome. Further, there is the
potential for differences in mitochondrial DNA distribution to affect
phenotype.
• These embryos are then placed in an empty zona pellucida and transferred to
recipient females, which carry them to term. Through 2001, a total of 2,226
registered Holstein clones—754 males and 1,472 females—were produced
from embryo splitting, with 1 to 2 percent of calves produced (NAAB,
2000).
• Genetic Engineering

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 Cloning as a technique, and the implications for predicting and assessing
adverse health effects that may be associated with this technique, are
addressed in the committee's subreport that follows this report.
Techniques employed to introduce novel genes into domestic animals are
discussed in detail in the report Animal Biotechnology: Science Based
Concerns (NRC, 2002). These transgenic approaches applicable to animals
are summarized in the following text.
• Accessing the Germline of Animals
Germline refers to the lineage of cells that can be genetically traced from
parent to offspring. It is possible to access the germline of animals using one
of five methods (NRC, 2002):
1.directly manipulating the fertilized egg after it has been implanted in the
uterus;
2.manipulating the sperm that produces the zygote;
3.manipulating early embryonic tissue in place;
4.using embryonic stem cell lines in early embryos.
5.manipulating cultured somatic cells to transfer their nuclei into enucleated
oocytes.
• Transfection
Several of the methods used to transfect or introduce novel genes into
animals are similar to those used for plants. Commonly used methods
include:
microinjection of DNA into the nucleus of anchored cells;
electroporation, where DNA is introduced through cell membrane pores by
pulsed electrical charges;
polycationic neutralization of the cell membrane and the DNA to be
introduced to improve passive uptake;
lipofection, where DNA is; and
sperm-mediated transfection, often used in conjunction with
intracytoplasmic sperm injection or electroporation.
As is the case with plants, microinjection is a highly inefficient means of
creating transgenic animals. For example, an incredibly small percentage of
livestock embryos that undergo microinjection yield transgenic animals

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 (Rexroad, 1994). Moreover, successfully microinjected transgenic animals
do not necessarily pass their transgenes on to their offspring (NRC, 2002).
• Retroviral Vectors
This method is similar to viral delivery methods used in plants in that virus
strains are modified to carry genetic material into a cell. It differs in that
after the novel DNA is delivered, the viral replication process integrates it
into the host cell's genome.
• Transposons
The use of transposable elements in animal cells has not been completely
developed. Although no active naturally occurring transposable elements
have been found in mammals, those found in insects and fish are under
investigation for potential use in animals.
• Knock-In and Knock-Out Technology
Transgenic technology can also be used to create organisms that lack
specific genes or those in which one existing gene has been replaced by
another that has been engineered. The addition (“knock-in”) or deletion
(“knock-out”) of specific gene functions through introduced mutations or
genetic engineering based on homologous recombination has become
commonplace in animals used for experimentation, such as mice. Although
at present this technology is not efficient and thus not practical for use in
generating knock-in or knock-out domestic animals, there are examples of
its use in domestic sheep and pigs. (NRC, 2002).
• Marker-Assisted Selection
Marker-assisted selection involves establishing a link between inheriting a
desirable trait, such as milk yield, and segregating specific genetic markers
that are coupled to that trait. Marker-assisted selection is important in animal
breeding and selection strategies for studying complex traits governed by
many genes (Georges, 2001). The use of this method is expected to increase
exponentially as genome-sequencing projects identify greater numbers of
useful, segregated markers for economically important traits.
Initially animals will be screened for genes that control simple traits that
may be undesirable, such as horns in cattle or metabolic stress syndrome in
pigs. In time, easily identifiable markers that accompany multiple genes
controlling more complex traits, such as meat tenderness and taste, growth,

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 offspring size, and disease resistance, will become available to improve
animal health and production traits (Dekkers and Hospital, 2002).
Two notable examples can be found in sheep. One is the Booroola gene in
which a single-nucleotide base change is responsible for the callipygian
muscle hypertrophy phenotype—the only known example of polar over-
dominance in a mammal (Freking et al., 2002). Another is introgression of
the Boorowa gene into the Awassa and the Assaf dairy breeds (Gootwine,
2001).
Sequencing genomes of animals that are important to agriculture will
identify genes that influence reproductive efficiency. For example, a growth-
hormone receptor variant on bovine chromosome 20 affects the yield and
composition of milk, and is expected to increase milk production by 200 kg
per lactation and decrease milk fat from 4.4 percent to 3.4 percent (Fletcher,
2003).
• Nontrans genic Methods of Animal Manipulation
Biotechnology can be used to modify endocrine function of domestic animals
and affect reproduction, lactation, and growth. For example, in pigs and rats
(Draghia-Akli et al., 2002) hypothalamic-specific expression of growth-
hormone-releasing hormone is not essential since ectopic expression of a
cloned DNA for this neuropeptide can be genetically driven by a synthetic
muscle-specific transcriptional promoter to elicit increases in both growth
hormone and insulin-like growth factor-I (Khan et al., 2002). This
biotechnology has the potential, by using specific hormones and growth
factors during critical developmental periods, to enhance uterine capacity and
to increase milk production.
• Factors affecting GMOs:

• Rules and legislation: Government rules play an important role in the introduction
and production of GMOs. Different countries have different legal frameworks for
the approval, labeling and cultivation of genetically modified crops.

• Public perception and acceptance: Public perception of GMOs can significantly

affect their market launch and acceptance. Concerns about health, environmental

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impact and ethical considerations can influence consumer attitudes and purchasing
decisions.

• Scientific research and development: Advances in biotechnology and genetic

engineering are driving the development of new GMOs with improved traits such as
pest resistance, drought tolerance , and nutritional supplements. Continued research
is essential to understand the potential benefits and risks associated with GMOs.

• Environmental effects: GMOs can have both positive and negative environmental
effects. The environmental sustainability of GMOs can be influenced by factors such
as the potential for gene transfer to wild relatives,

effects on non-target organisms and changes in agricultural practices.

• Economic considerations: Economic factors, including production costs, market

demand, and intellectual property rights, affects the introduction and
commercialization of GMOs. Farmers weigh the potential benefits of GMOs, such
as increased yields and reduced pesticide use, against their costs and market
opportunities..

2.Evolution Theory
• Abstract
Evolution is both a fact and a theory. Evolution is widely observable in laboratory
and natural populations as they change over time. The fact that we need annual flu
vaccines is one example of observable evolution. At the same time, evolutionary
theory explains more than observations, as the succession on the fossil record.
Hence, evolution is also the scientific theory that embodies biology, including all
organisms and their characteristics. In this paper, we emphasize why evolution is
the most important theory in biology. Evolution explains every biological detail,
similar to how history explains many aspects of a current political situation. Only
evolution explains the patterns observed in the fossil record. Examples include the
succession in the fossil record; we cannot find the easily fossilized mammals
before 300 million years ago; after the extinction of the dinosaurs, the fossil record
indicates that mammals and birds radiated throughout the planet. Additionally, the

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fact that we are able to construct fairly consistent phylogenetic trees using distinct
genetic markers in the genome is only explained by evolutionary theory. Finally,
we show that the processes that drive evolution, both on short and long time scales,
are observable facts.

Keywords: evolutionary theory, science, scientific method, scientific theory,

macroevolution

• Evolution as a fact and thoery

Evolution is a population concept. An individual does not evolve; only populations
evolve in the face of the genetic changes accumulated from one generation to the
next. The flu virus evolves. This explains why last years’ flu vaccine does not work
on the current strain of the virus: only the resistant strains of the virus survived last
year’s vaccine application. This is a textbook example of evolution by natural
selection. Genetic modifications are encountered in the resistant strains; thus,
evolution is a fact (Gould, 1981). Mutation, migration, natural selection, and
genetic drift are the evolutionary forces that drive genetic changes of natural
populations from one generation to the next. This is known among biologists as
microevolution.

On the other hand, evolutionary theory explains more than those facts that we can
routinely observe. This makes it a theory, but is it just a theory? The word theory has
distinct meanings in science and in lay language (Ghose, 2013). A scientific theory
is the utmost position an idea may reach in science. Outside of academia, however,
a theory is equivalent to a hypothesis, an idea that explains facts but has never been
tested (Futuyama and Kirkpatrick, 2017). This occurs because there seems to be no
need for a distinction between hypothesis and theory outside the scope of science.
In science, however, this distinction is fundamental. An idea remains a hypothesis if
it has never been confronted with new (independently collected) scientific data that
would serve as a test for its predictions. If a hypothesis has endured further testing
by subsequent scientific experiments, in time it becomes a valid scientific theory.

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 • Evolutionary processes that drive micro and macroevolution are
facts
To have a better understanding of evolution, we must discuss the processes that
drive evolution. For this, we start by comparing processes that drive
microevolution with those that drive macroevolution. Many of the same
evolutionary processes that drive microevolution also drive macroevolution,
namely natural selection, mutation, migration, and genetic drift. A lineage will tend
to diversify if it has adaptations that increase survival and reproductive abilities
compared to other species. This advantage will tend to increase population size and
the geographical distribution of the ancestral species that will more likely speciate
into two descendant species. Hence, according to this view, macroevolution is
microevolution on a larger scale (Zimmer, 2001), with biological speciation as the
only additional process (Russo et al., 2016). Through speciation, one ancestral
species gives rise to two descendant species that are reproductively incompatible
with each other.

More than a million species have been described (Mora et al., 2011), and each
biological species includes many interbreeding members. Also, most species are
reproductively isolated from each other. The fact that we observe biological species
with interbreeding members and reproductive isolation between species is
compatible with both separate creation and macroevolution. So, which observable
pattern would we expect if many speciation events generated the vast biological
diversity from a single common ancestor? In this case, we would expect different
degrees of similarity between reproductively isolated species. This is exactly what
we observe. Some species are very similar, such as chimpanzees and gorillas, with
most features shared between them. Other species, on the other hand, are
morphologically so different that one must look into cytology, physiology, or
comparative genomics to detect evidence of their common past. One example is a
fern and a frog. For instance, the cellular respiration is a process shared by ferns
and frogs and it is an evidence of their common ancestry. Only macroevolution
explains well the distinct degrees of similarity between these four isolated species,
as the age of their last common ancestor is inversely proportional to the similarity
between any two species.

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Furthermore, the existence of hybrids, such as the mule, the liger, the coywolf, is
also only explained by the hierarchical common ancestry theory, not by separate
creation. The hybrids are direct evidence of on-going processes of speciation.
Thus, the presence of hybrids is what we would expect if all life had a common
ancestry.

Other fossil record patterns are well explained by macroevolution. For instance, why
do we find a major increase in mammalian fossil diversity only after the
disappearance of non-avian dinosaurs approximately 65 million years ago? The
same pattern is observed in the fossil record of birds. Macroevolution explains this
well, as the extinction of dinosaurs eliminated competition, and the surviving
ancestral mammals were able to increase in number and diversified through
speciation, generating more species of their kind.

• Final remarks
A single, very well designed experiment, performed in accordance with the utmost
scientific standards, is what it takes to put any scientific theory to rest. Divine
creation will never be part of science because science is not able to detect
supernatural phenomena. Divine phenomena explain everything equally; hence, it
provides no real explanatory (i.e., predictive) power. If we accept “God’s will” as
an adequate explanation for a natural phenomenon, we eliminate the possibility of
eventually being able to explain it naturally. Thus, the scientific revolution begun
when we eliminated the divine as a scientific explanation.

Science, as a process, starts with the acceptance of our ignorance about a natural
phenomenon and by seeking natural explanations for it. Hence, ignorance drives
the engine of Science. Even if evolution were, hypothetically, rejected, contested
by new data, scientists would have to study hard to find an alternative natural
explanation that was able to explain everything that evolution explains today plus
the new data that contested it.

Evolution is a fact and a well-supported scientific theory. It has endured daily and
rigorous testing, and it stands as the unifying theory in biology (Rutledge and
Warden, 2000). This says nothing about whether God created or did not create the

19
world, as science is unable to distinguish a divinely guided evolution from a
materialistic evolution. God may well have created the biological world through
natural selection, mutation, speciation, extinction, etc. Still, evolution and Science
would remain unscathed as Science is not concerned with why or who, but only
with how.

Some creationists say that we must bring the evolution versus creationist debate to
the classroom and claim that the opposition to the debate is anti-scientific. However,
science is not about blind criticism (Meyer and El-Hani, 2013). Blind criticism is
just as naïve as blind acceptance. Scientists must weigh the evidence before
questioning a theory. The idea that all debates are equally scientific is misleading
and it explains the sad emergence of flat-earthers and anti-vaxxers. A debate on what
is the shape of our planet is not only pointless, but it is also dangerously harmful to
the minds of the young students. A fruitful debate in a science class is restricted to
those issues that lie within the scientific realm (Baltzley, 2016, Branch, 2016).

• Mechanism and factors

We’ve defined evolution as descent with modification from a common ancestor,
but exactly what has been modified? Evolution occurs when there is a change in
the heritable information passed from one generation to thenext. Typically, we
think of biological evolution as changes in gene frequency within a population
over time – if, say, birds with genes that produce wide beaks went from being rare
to being common over multiple generations. But biological evolution also includes
changes in DNA that does not code for genes and changes in heritable information
not encoded in DNA at all. In all of these cases, the modifications are heritable and
can be passed on to the next generation — which is what really matters in
evolution: long term change. Here, we’ll focus on changes in genes and other
genetic elements

(e.g., in non-coding DNA) as they relate to evolution.

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1. Mutation
A mutation could cause beetle parents with genes for bright green coloration
to have offspring with a gene for brown coloration. That would make genes
for brown coloration more frequent in the population than
they were before the mutation.
Mutations are changes in the information contained in
genetic material. For most of life, this means a change in the
sequence of DNA, the hereditary material of life. An
organism’s DNA affects how it looks, how it behaves, its
physiology — all aspects of its life. So a change in an organism’s DNA can
cause changes in all aspects of its life. Mutations are random Mutations can
be beneficial, neutral, or harmful for the organism, but mutations do not “try”
to supply what the organism “needs.” In this respect, mutations are random
— whether a particular mutation happens or not is unrelated to how useful
that mutation would be. Not all mutations matter to evolution Since all cells
in our body contain DNA, there are lots of places for mutations to occur;
however, not all mutations matter for evolution. Somatic mutations occur in
non-reproductive cells and so won’t be passed on to offspring. For example,
the yellow color on half of a petal on this red tulip was caused by a somatic
mutation. The seeds of the tulip do not carry the mutation. Cancer is also
caused by somatic mutations that cause a particular cell lineage (e.g., in the
breast or brain) to multiply out of control. Such mutations affect the individual
carrying them but are not passed directly on to offspring.

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 2. Genetic Drift
Genetic drift: In one generation, brown beetles
happened to have many offspring survive to reproduce.
In the same generation, a number of green beetles were
killed randomly when someone stepped on them and
had no offspring. The next generation had more brown
beetles than the previous generation — but just

3. Natural Selection

: Imagine that green beetles are easier for birds to spot (and hence, eat). Thus, brown
beetles are a little more likely to survive to produce offspring. They pass their genes
for brown coloration on to their offspring. So in the next
generation, brown beetles are more common than they
were in the previous generation. All of these
mechanisms can cause changes in the frequencies of
genes and other genetic elements in populations, and so
all of them are mechanisms of evolutionary change.
However, natural selection and genetic drift can only
change the frequency of different genes and genetic elements (e.g., making wide
beaks or green beetle s more or less common); they cannot introduce fundamentally
new traits to a population.

4. Gene Flow
Gene flow — also called migration — is any movement of individuals, and/or the
genetic material they carry, from one population to another. Gene flow includes
lots of different kinds of events, such as pollen being blown to a new destination or
people moving to new cities or countries. If genetic variants are carried to a
population where they previously did not exist, gene flow can be an important
source of genetic variation. In the graphic below, a beetle carries the gene version
for brown coloration from one population to another.

22
 The
genetic
variation in modern human populations has been critically shaped by gene flow.
For example, by sequencing ancient DNA, researchers have reconstructed the
entire Neanderthal genome – and they’ve found that many snippets of these archaic
sequences live on in modern humans. It’s clear that ancient humans and
Neanderthals interbred, and that this gene flow introduced new genetic variation to
the human population. Furthermore, this ancient gene flow seems to affect who we
are today. Neanderthal gene versions have been linked to immune functions,
metabolic functions (e.g., affecting one’s risk of developing diabetes), and even
skin color.

• Genetic Variations
Without genetic variation, some key mechanisms of evolutionary change like
natural selection and genetic drift cannot operate. There are three primary
sources of new genetic variation: 1. Mutations are changes in the information
contained in genetic material. (For most of life, this means a change in the
sequence of DNA.) A single mutation can have a large effect, but in many
cases, evolutionary change is based on the accumulation of many mutations
with small effects. 2. Gene flow is any movement of genetic material from one
population to another (e.g., through migration) and is an important source of
genetic variation. 3. Sex can introduce new gene combinations into a
population. This genetic shuffling is another important source of genetic

23
variation.

Sex and genetic shuffling

Sex can introduce new gene
combinations into a population and is
an important source of genetic
variation. You probably know from
experience that siblings are not
genetically identical to their parents
or to each other (except, of course, for
identical twins). That’s because when
organisms reproduce sexually, some
genetic “shuffling” occurs, bringing
together new combinations of genes.
For example, you might have bushy
eyebrows and a big nose since your
mom had genes associated with
bushy eyebrows and your dad had
genes associated with a big nose.
These combinations can be good,
bad, or neutral. If your spouse is wild
about the bushy eyebrows/ big nose combination, you were lucky and hit on
a winning combination! This shuffling is important for evolution because it
can introduce new combinations of genes every generation. For example, in a
particular population, plants with reddish flowers and plants with longer more

24
tubular flowers might each do fine on their own – but if sex and genetic
shuffling produced a plant with both traits (red tubular flowers), the
combination might attract a new pollinator (hummingbirds) and alter the
evolutionary trajectory of the lineage. Of course, sex and genetic shuffling can
also break up good combinations of genes and form bad ones.
Factors affecting evolution:
1. Genetic variation refers to the differences in DNA sequences among
individuals within a population or species. Several factors contribute to
genetic variation in organisms, influencing the diversity observed within
and among populations. Here are some key factors:
2. Mutation: Mutations are changes in the DNA sequence of an organism's
genome. They can occur spontaneously during DNA replication or as a
result of exposure to external factors such as radiation or certain chemicals.
Mutations are a primary source of genetic diversity.
3. Recombination: Recombination occurs during the formation of
reproductive cells (gametes) in sexually reproducing organisms. It
involves the shuffling and exchange of genetic material between
homologous chromosomes, leading to new combinations of alleles in
offspring.
4. Sexual Reproduction: Sexual reproduction itself introduces genetic
variation. Offspring inherit a unique combination of genes from both
parents, contributing to genetic diversity within a population.
5. Gene Flow (Migration):Gene flow refers to the movement of genes
between different populations. It occurs when individuals migrate,
bringing their genetic material to new populations. This can prevent
populations from becoming genetically isolated and can increase genetic
diversity.
6. Descent with Modification: As advantageous traits become more
common in a population through natural selection, populations may
diverge from their ancestors, resulting in the formation of new species over
long periods of time. This process, known as descent with modification,
accounts for the diversity of life observed on Earth.

25
 3. The relation between genetically modified organisms and
evolution theory
The introduction of genetic modifications into plants and animals in laboratory
settings has indeed provided a means to bypass traditional evolutionary processes.
These genetically modified organisms (GMOs) offer significant advantages for the
food supply, including accelerated crop production, enhanced resistance to pests,
and the creation of more nutritious food sources. However, before unleashing
GMOs into natural ecosystems, it is paramount to thoroughly grasp the potential
risks associated with their production and release.

One major concern revolves around the potential impact of GMOs on genetic
diversity within plant and animal populations. Genetic diversity refers to the
variety of genetic characteristics within a species, which is crucial for ensuring the
resilience and adaptability of populations to environmental changes. When GMOs
are introduced, there is a risk of reducing genetic diversity as the DNA sequences,
responsible for encoding proteins within organisms, become more homogenous
across individuals of the same species. This reduction in genetic diversity can have
profound implications for biodiversity, which encompasses the variability in traits
among organisms that form an ecosystem. Genetic diversity directly influences
biodiversity because it determines the range of traits present within populations,
thereby shaping the overall composition and functioning of ecosystems. Preserving
genetic diversity is essential for both environmental conservation and sustainable
agriculture, as a greater diversity of DNA sequences provides organisms with a
broader range of traits to draw upon for adaptation to shifting environmental
conditions.In essence, while GMOs offer promising solutions to pressing
agricultural challenges, it is crucial to approach their development and deployment
with caution. Safeguarding genetic diversity within natural populations is
paramount to maintaining the resilience and long-term sustainability of ecosystems
and agricultural systems alike. Therefore, comprehensive risk assessments and
robust regulatory frameworks must be in place to mitigate the potential adverse
impacts of GMOs on genetic diversity and biodiversity.

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References:

• National Academies Press (US). (2004). Methods and mechanisms for genetic

manipulation of plants, animals, and microorganisms. Safety of Genetically

Engineered Foods - NCBI Bookshelf.

https://www.ncbi.nlm.nih.gov/books/NBK215771/

• Bierkland NK, Holo H. 1993. Transduction of a plasmid carrying the cohesive end

region from Lactococcus lactis bacteriophage LC3. Appl Environ Microbiol

59:1966–1968. [PMC free article] [PubMed]

• Cold Spring Harbor Laboratory. 1951. Cold Spring Harbor Symposium on

Quantitative Biology XVI: Genes and Mutations . Online. Available at http://library

.cshl.edu/symposia/1951/index.html. Accessed November 4, 2003.

• Heyman Y, Vignon X, Chesne P, Le Bourhis D, Marchal J, Renard JP. 1998. Cloning

in cattle: From embryo splitting to somatic nuclear transfer. Reprod Nutr Dev

38:595–603.

• Zimnoch-Guzowska E, Marczewski W, Lebecka R, Flis B, Schafer-Pregl R,

Salamini F, Gebhardt C. 2000. QTL analysis of new sources of resistance to Erwinia

carotovora ssp. atroseptica in potato done by AFLP, RFLP, and resistance-gene-like

markers. Crop Sci 40:1156–1167.

27
• Sears ER. 1956. The transfer of leaf rust from Ae. umbellulata to wheat. Brookhaven

Symp Biol 9:1–22.

• Russo, A. M., & André, T. (2019). Science and evolution. Genetics and Molecular

Biology, 42(1), 120-124. https://doi.org/10.1590/1678-4685-GMB-2018-0086

• Ross E. Revamped ‘anti-science’ education bills in United States find success. 2017.

[accessed 19 January 2019]. https://www.nature.com/news/revamped-anti-science-

education-bills-in-united-states-find-success-1.21986

• Zimmer C. Evolution, the triumph of an idea. Harper Collins; New York: 2001. p.

528. [Google Scholar]

Zimmer C (2001) Evolution, the triumph of an idea. Harper Collins, New York, 528

p.

• Russo, C., & André, T. (2019). Science and evolution. Genetics and Molecular

Biology, 42(1), 120–124. https://doi.org/10.1590/1678-4685-gmb-2018-0086

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