principles of genetics

Document Sample
principles of genetics Powered By Docstoc

1. Agriculture (Plant and Animal Breeding)
Genetics deal not only with the way in which characteristic are transmitted
from one generation to the next, but also with how genes bring about the
characteristics that they control. Scientist has been using genetics to bring
about        many       changes       that      benefit      human       beings.
Genetics has many practical applications which are of great value to human
beings. In agriculture, for example, knowledge of principles of heredity is very
important when it comes to increasing food production. The fat, beef and milk
production cattle of today are a far away from the scrawny animals that used
to graze the fields decades ago. Many of our domestic animals have been
greatly transformed by practical applications of genetic principles such as
selective breeding. One of the best-known and controversial applications of
genetics is the creation and use of genetically modified crops or genetically
modified organisms, such as genetically modified fish, which are used to
produce genetically modified food and materials with diverse uses. The main
goals in generating genetically modified crops are these;
One goal, and the first to be realized commercially, is to provide protection
from environmental threats, such as cold (in the case of Ice-minus bacteria),
or pathogens, such as insects or viruses, and/or resistance to herbicides.
There are also fungal and virus resistant crops developed or in development.
They have been developed to make the insect and weed management of
crops easier and can indirectly increase crop yield.
Another goal in generating GMO (genetically modified organism )is to modify
the quality of the produce, for instance, increasing the nutritional value or
providing more industrially useful qualities or quantities of the produce. Some
agriculturally important animals have been genetically modified with growth
hormones to increase their size. The Am flora potato, for example, produces
a more industrially useful blend of starches. Cows have been engineered to
produce more protein in their milk to facilitate cheese production. Soybeans
and canola have been genetically modified to produce more healthy oils.
These modified crops would also reduce the usage of chemicals, such as
fertilizers and pesticides, and therefore decrease the severity and frequency
of the damages produced by this chemical pollution

Selective breeding involves the cross-breeding of two parents, each with
some good traits, to produce offspring with the good straits of both parents.
Selective breeding in livestock can be carried out by means of artificial
insemination, in vitro fertilization and embryo transfer. Through the application
of genetics, scientists have been able to produce domestic animals with
superior qualities. The same can be said of the plant breeders who have been
successful in producing superior varieties of food crops that we have a
surplus of these crops today.
Selective breeding has its benefits. New varieties of crops and livestock have
been produced which have better yield, better resistance to pests and
diseases, and with improved nutritional value. These new varieties have
helped increase local food production and cut down food imports.

Medical genetics encompasses many different areas, including clinical
practice of physicians, genetic counselors, and nutritionists, clinical diagnostic
laboratory activities, and research into the causes and inheritance of genetic
disorders. Examples of conditions that fall within the scope of medical
genetics include birth defects, mental retardation, autism, and mitochondrial
disorders, skeletal dysphasia, connective tissue disorders, cancer genetics,
dermatogens, and prenatal diagnosis. Medical genetics is increasingly
becoming relevant to many common diseases. Overlaps with other medical
specialties are beginning to emerge, as recent advances in genetics are
revealing etiologies for neurological, endocrine, cardiovascular, pulmonary,
ophthalmologic, renal, psychiatric, and dermatologic conditions.
In the field of medicine, research has revealed how heredity plays a part in
many diseases. Several serious human diseases, certain of the eye, and
disabilities like color blindness and dwarfism are all influenced by heredity.
For many diseases, an accurate diagnosis can be made more quickly and
accurately through a study of one’s family history than through elaborate and
expensive laboratory tests. Also, it is possible to avoid many serious mistakes
in diagnosis through the application of genetic. Genetics is also important in
preventing medicine. In many cases, it is possible to anticipate the
development of a disease or other body abnormalities based on family
history. Thus, appropriate steps can be taken to prevent its occurrence. A
person with a family history of diabetes might be prepared for the onset of the
disease and take the necessary steps and precautions to prevent it from
getting worse. Recent advances in genetic research have provided new
opportunities for maintaining health, screening for increased performance
potential and identifying athletes and persons recreationally active who are at
risk for pathology. Throughout medical history, traits associated with affected
persons have been chosen and evaluated for their presence in other family
It has been estimated that mankind is plagued by about 2000 genetic
diseases. About 18-20% of newborns are affected by one or more hereditary
problems. Many disease and abnormalities are known to have a genetic
base. Hemophilia, some types of diabetes and anemia are few conditions
those are in this category.
In medicine genetic engineering has been used to mass-produce insulin,
human growth hormones, fillister (for treating infertility), human albumin,
monoclonal antibodies, ant hemophilic factors, vaccines and many other
drugs. Vaccination generally involves injecting weak live, killed or inactivated
forms of viruses or their toxins into the person being immunized.
   Genetically engineered viruses are being developed that can still confer
   immunity, but lack the infectious sequences. Genetic engineering is used to
   create animal models of human diseases. Genetically modified mice are the
   most common genetically engineered animal model. They have been used to
   study and model cancer (the nocuous), obesity, heart disease, diabetes,
   arthritis, substance abuse, anxiety, aging and Parkinson disease. Potential
   cures can be tested against these mouse models. Also genetically modified
   pigs have been bred with the aim of increasing the success of pig to human
   organ transplantation.

3. Animal husbandry
Animal husbandry is the scientific breeding and management of domesticated
livestock to achieve qualities desired to meet various nutritional, labor,
recreational, and other derivative needs, such as leather, fur, and pharmaceutical
sources. Early humans recognized traits in certain animals which they bred to
create offspring with those characteristics. Animals which did not meet
expectations were culled from breeding stock and sometimes castrated or
slaughtered. These primitive animal husbandry methods were based on
observation and experience, not genetics.
Animal husbandry became professionalized in the twentieth century as scientists
theorized and determined ways to manipulate livestock's genes regarding such
factors as growth and biochemical activity. Jay L. Lush (1896-1982), an Iowa
State University animal husbandry professor, is considered the father of modern
animal breeding and        genetics.      His    research       resulted    in    an
international breeding study center being established at Iowa State that
continues to influence animal husbandry world-wide.
Livestock breeders who accept genetic principles carefully choose breeding
stock to develop lines that consistently produce animals with similar
characteristics. Genetics technology enables breeders to cultivate meatier,
tastier,      larger,    speedier,     or     sturdier     animals.      Aware    of
plant breeding experiments, animal husbandry researchers recognize the value
of true-line breeding to reinforce certain ideal genetic traits such as strength and
vigor associated with specific breeds. Genetically similar animals usually produce
offspring which have the same characteristics.
Inbreeding is a genetic strategy to produce superior specimens by mating
animals closely related in an attempt to concentrate desirable genetic material in
offspring. Recessive inferior genes that are not detectable in the parents,
however, may become visible in the offspring which might be smaller or express
some other weakness and undesirable traits. Out crossing involves breeding
unrelated animals of the same breed in an attempt to develop their outstanding
traits in offspring. Crossbreeding, or the mating of animals from two breeds of the
same species, is another method to achieve better quality livestock who obtain
higher prices at market. Hybrids such as a cross between a sheep and a goat
represent desirable traits of each species.
Scientists also achieved the cry preserving of many livestock species' embryos to
enable efficient production to meet consumer demands and generate profits.
Sophisticated genetics techniques have advanced animal husbandry. Livestock
breeders can custom design animals to meet their demands. They can select the
gender of animals and characteristics such as leanness that may earn more
money at markets. Animal husbandry professionals also rely on genetics to save
money. Geneticists use DNA markers for mapping the genetic potential of calves
so that breeders can determine whether those animals will mature into
viable breeding stock.

There are even legal applications of the principles of heredity. Court cases
involving questions of percentage can be solved by an analysis of blood types
and DNA. Crimes have also been solved and suspects been charged or
acquitted with the use of DNA testing. genetic technology – specifically the
development of DNA "fingerprinting," which looks for certain repeating patterns
within the non-coding regions of DNA (so called variable number tandem repeats
or VNTRs) has led to the widespread use of genetic testing for identification. In
the criminal context, fingerprinting is used to link samples found at a crime scene
with specific victims or perpetrators of a crime. Genetic testing has also been
used to exonerate those wrongly accused of a crime by demonstrating that their
DNA does not match the evidence found at the crime scene. More recently,
genetic profiling technology has permitted law enforcement to narrow the field of
potential suspects by technology that permits a prediction of the likely racial or
ethnic makeup of a suspect. Similarly controversial are the uses of so-called
"DNA dragnets" to include and exclude suspects within a certain geographic area
and the creation of DNA banks to store the samples of those convicted or
accused of a crime. Beyond the criminal context, DNA fingerprinting has been
used to identify victims of disasters and to confirm or disprove paternity and

Advances in reproductive technologies have forced the law to broaden its notion
of family from one defined by simple genetic relatedness. The use of donor eggs
and sperm, gestational surrogates, and in vitro fertilization has led to cases of
contested claims of parentage, which courts have had to sort through. Courts
generally apply a "best interest of the child" standard in sorting through
competing claims of parentage, and may take into account the claims of the
genetic parents, the gestational parent, and the so-called "intended" parent in
determining which parenting arrangement would be in the child’s best interest.
Problems of baby mix-up in the hospital can also solve.

Gene therapy is an experimental technique that uses genes to treat or prevent
disease. In the future, this technique may allow doctors to treat a disorder by
inserting a gene into a patient’s cells instead of using drugs or surgery.
Researchers are testing several approaches to gene therapy, including:
      Replacing a mutated gene that causes disease with a healthy copy of the
      Inactivating, or “knocking out,” a mutated gene that is functioning
      Introducing a new gene into the body to help fight a disease.
Although gene therapy is a promising treatment option for a number of diseases
(including inherited disorders, some types of cancer, and certain viral infections),
the technique remains risky and is still under study to make sure that it will be
safe and effective.
Types of gene therapy
    Somatic gene therapy
In somatic gene therapy, the therapeutic genes are transferred into the somatic
cells, or body, of a patient. Any modifications and effects will be restricted to the
individual patient only, and will not be inherited by the patient's offspring or later
generations. Somatic gene therapy represents the mainstream line of current
basic and clinical research, where the therapeutic DNA transience (either
integrated in the genome or as an external plasmid) is used to treat a disease in
an individual.
     Germ line gene therapy
In germ line gene therapy, Germ cells, i.e., sperm or eggs are modified by the
introduction of functional genes, which are integrated into their genomes. This
would allow the therapy to be heritable and passed on to later generations.
Although this should, in theory, be highly effective in counteracting genetic
disorders and hereditary diseases, many jurisdictions prohibit this for application
in human beings, at least for the present, for a variety of technical and ethical
Gene therapy is the use of DNA as a pharmaceutical agent to treat disease. It
derives its name from the idea that DNA can be used to supplement or alter
genes within an individual's cells as a therapy to treat disease. The most
common form of gene therapy involves using DNA that encodes a functional,
therapeutic gene in order to replace a mutated gene. Other forms involve directly
correcting a mutation, or using DNA that encodes a therapeutic protein drug
(rather than a natural human gene) to provide treatment. In gene therapy, DNA
that encodes a therapeutic protein is packaged within a "vector", which is used to
get the DNA inside cells within the body. Once inside, the DNA becomes
expressed by the cell machinery, resulting in the production of therapeutic
protein, which in turn treats the patient's disease.

Genetic counseling is the process by which patients or relatives, at risk of an
inherited disorder, are advised of the consequences and nature of the disorder,
the probability of developing or transmitting it, and the options open to them in
management and family planning. This complex process can be separated into
diagnostic (the actual estimation of risk) and supportive aspects
Genetic counseling is the process of:
       1 .Evaluating family history and medical records
       2. Ordering genetic tests
       3. Evaluating the results of this investigation
       4. helping parents understand and reach decisions about what to do next
The goals of genetic counseling are to increase understanding of genetic
diseases, discuss disease management options, and explain the risks and
benefits of testing. Counseling sessions focus on giving vital, unbiased
information and non-directive assistance in the patient's decision making
process. Seymour Kessler, in 1979, first categorized sessions in five phases: an
intake phase, an initial contact phase, the encounter phase, the summary phase,
and a follow-up phase. The intake and follow-up phases occur outside of the
actual counseling session. The initial contact phase is when the counselor and
families meet and build rapport. The encounter phase includes dialogue between
the counselor and the client about the nature of screening and diagnostic tests.
The summary phase provides all the options and decisions available for the next
step. If counselees wish to go ahead with testing, an appointment is organized
and the genetic counselor acts as the person to communicate the results.
Families or individuals may choose to attend counseling or undergo prenatal
testing for a number of reasons.
     Family history of a genetic condition or chromosome abnormality
     Molecular test for single gene disorder
     Increased maternal age (35 years and older)
     Increased paternal age (40 years and older)
     Abnormal maternal serum screening results or ultrasound findings
     Increased niche translucency measurements on ultrasound
     Strong family history of cancer
     Predictive testing for adult-onset conditions

If a person is diagnosed with a genetic condition, the genetics professional
provides information about the diagnosis, how the condition is inherited, the
chance of passing the condition to future generations, and the options for testing
and treatment.


Over the past 20 years, DNA-based biotechnologies have been applied to
agricultural production and many crops with new and useful attributes have been
cultivated in various countries. The adoption of this new technology by farmers
has been swift, and benefits in terms of increased production per unit land and
environmental benefits are becoming obvious. In forestry, the application of
biotechnology is somewhat lagging behind and to date there are no commercial
plantations with genetically modified trees. However, most tree species used in
plantation forestry have been genetically transformed, and results demonstrate
the successful and correct expression of new genes in these plants. At the same
time, this new technology is being viewed with concern, very similar to the
concerns voiced over the use of genetic engineering in agriculture. This paper
discusses some of the issues involved for world forestry, with particular focus on
future demand for timber and timber products and how modern biotechnology
can contribute to meet the growing demand. Tree genetic engineering techniques
will be outlined, and results reviewed for a number of species. Concerns over the
use of this new technology will be described and analyzed in relation to scientific


Data on human genetic variation help scientists to understand human origins,
susceptibility to illness and genetic causes of disease. Destructive episodes in the
history of genetic research make it crucial to consider the ethical and social
implications of research in genomics, especially human genetic variation. The
analysis of ethical, legal and social implications should be integrated into genetic
research, with the participation of scientists who can anticipate and monitor the full
range of possible applications of the research from the earliest stages. The design
and implementation of research directs the ways in which its results can be used,
and data and technology, rather than ethical considerations or social needs, drive the
use of science in unintended ways. Here we examine forensic genetics and argue
that all geneticists should anticipate the ethical and social issues associated with non
medical               applications           of             genetic            research.
Data on human genetic variation are being generated and used to better understand
human origins, susceptibility to illness and genetic causes of disease. The US
National Human Genome Research Institute (NHGRI) recently proposed the next
stage in this work to carry forward and expand these goals and to reaffirm a
commitment, present since the start of the Human Genome Project, that appropriate
uses of this information will be based on ethical, legal and social science analysis.

The history of destructive episodes in genetic research makes this attention to the
ethical and social implications of genomics research essential. This is especially true
of human genetic variation research, because it provides the opportunity to find the
genetic basis of individual and group differences. The consideration of ethical, legal
and social implications (ELSI) of genetic research will not be maximally effective if it
separates the creation of knowledge from its uses or if it sees the solution to
appropriate uses of science as coming from a "cohort of scholars in ethics, law, social
science, clinical research, theology, and public policy” rather than emerging with and
from the science. Thus, ELSI analysis should be integrated into science, with
participation of scientists; should be conducted proactively, rather than after
scientific research projects are conducted; and should anticipate and monitor
applications of research. A collaborative effort that centrally involves scientists and
dialog among many scientific communities is necessary to shape science for
responsible uses, because the way in which science is designed and carried out
fundamentally affects how it can be used. Too often, the mere availability of data
and technology, rather than ethical considerations or social needs, drives its use in
unintended ways; therefore, the awareness and involvement of scientists in thinking
about downstream uses is needed at the earliest stages of research.

NHGRI is a leader in the concept of ELSI analysis and recently involved scholars from
a diversity of backgrounds in planning large-scale projects such as the Hap Map.
Scholars from anthropology, law, ethics and other disciplines have had input in the
earliest stages of designing, carrying out and reporting genetic research intended to
identify genes involved in diseases, protection against illness and responses to drugs.
This multidisciplinary approach was perceived to 'slow' the research while issues such
as informed consent, community consultation and benefits were ironed out. But lack
of attention to issues important to the communities that are affected by the
research, and on whose behalf the research is purportedly done, can also slow or
even halt research and breed deep distrust of scientists that can only hurt future
efforts to carry out or rise funding for future research. Therefore, time spent making
explicit the ever-present ethical and social issues and incorporating them into study
design is better conceptualized as an integral part of the research process.

The Hap Map has been an exemplar of integrated and proactive ELSI analysis in
genetic variation research. Similar efforts have been organized for other genetic
research projects, such as the development of a pharmacokinetics research network
and database funded by the US National Institutes of Health. Far less attention has
been paid to the application of genetic variation research for non medical purposes,
however. The changing debate over gene patenting and the possible connection
between patent law and the ethical and policy concerns associated with the use
of genetic testing technologies (e.g. the premature implementation and
inappropriate marketing of genetic tests). Arguably, patent law helps to form the
market forces that lead to these concerns. It is suggested that existing
safeguards fail to control these concerns because of, for example, a lack of
provider knowledge and an absence of an adequate regulatory framework. While
patent law can be associated with a number of ethical and policy concerns, the
article also suggests that patent law may have a positive role in reducing them.
Patent law provides policy makers and the public with a focal point – the patent
holder – upon which to attach accountability for ethical and legal conduct.

Shared By: