DNA -Physical definitions

Physical definitions

The chemical structure of a four-base fragment of a DNAdouble helix.

The vast majority of living organisms encode their genes in long strands of DNA. DNA consists of a chain made from four types of nucleotide subunits: adenine, cytosine,guanine, and thymine. Each nucleotide subunit consists of three components: aphosphate group, a deoxyribose sugar ring, and a nucleobase. Thus, nucleotides in DNA or RNA are typically called 'bases'; consequently they are commonly referred to simply by their purine or pyrimidine original base components adenine, cytosine, guanine, thymine. Adenine and guanine are purines and cytosine and thymine are pyrimidines. The most common form of DNA in a cell is in a double helix structure, in which two individual DNA strands twist around each other in a right-handed spiral. In this structure, the base pairing rules specify that guanine pairs with cytosine andadenine pairs with thymine (each pair contains one purine and one pyrimidine). The base pairing between guanine and cytosine forms three hydrogen bonds, while the base pairing between adenine and thymine forms two hydrogen bonds. The two strands in a double helix must therefore be complementary, that is, their bases must align such that the adenines of one strand are paired with the thymines of the other strand, and so on.

Due to the chemical composition of the pentose residues of the bases, DNA strands have directionality. One end of a DNA polymer contains an exposed hydroxyl group on the deoxyribose, this is known as the 3' end of the molecule. The other end contains an exposed phosphate group, this is the 5' end. The directionality of DNA is vitally important to many cellular processes, since double helices are necessarily directional (a strand running 5'-3' pairs with a complementary strand running 3'-5') and processes such as DNA replication occur in only one direction. All nucleic acid synthesis in a cell occurs in the 5'-3' direction, because new monomers are added via a dehydration reaction that uses the exposed 3' hydroxyl as a nucleophile.

The expression of genes encoded in DNA begins by transcribing the gene into RNA, a second type of nucleic acid that is very similar to DNA, but whose monomers contain the sugar ribose rather than deoxyribose. RNA also contains the base uracil in place of thymine. RNA molecules are less stable than DNA and are typically single-stranded. Genes that encode proteins are composed of a series of three-nucleotidesequences called codons, which serve as the "words" in the genetic "language". The genetic code specifies the correspondence during protein translation between codons and amino acids. The genetic code is nearly the same for all known organisms.

Animal Testing Without Animals

Two researchers at the Rensselaer Polytechnic Institute have developed an Electric Cell-substrate Impedance Sensing (ECIS) device that uses electricity to study complex cell behavior. The device offers researchers a way of testing cell interactions through non-invasive means.

The ECIS device is an "electronic eavesdropper" on cells and can measure the activity of cells over time. Because it is connected via software to a computer, all data acquisition and analysis can be automated. Data about a cell's response can be taken as frequently as every quarter second.

The device works by electrically "culturing" live cells in a set of trays which sit in bays that are supplied with a low-level alternating current from an electrode. When electricity is present, cells will expand over the electrode, allowing changes to be measured.

This electrical sensor allows a new level of detail for the results. Instead of the traditionalpetri dish for cultures and examination by a microscope, the entire procedure is now automated.

Many people question the use of animals in research, particularly in nonessential testing. Others maintain that animal modeling is a necessary prerequisite for the discovery of new treatments. One target is the cosmetics industry. This device could markedly reduce or even eliminate the need to use live animals to test and measure the toxicity levels of chemicals.

The device is also cost effective. Data can be taken in real time essentially 24 hours a day with minimal human interaction. The device is manufactured by Applied BioPhysics and retails for approximately $40,000. Several large universities and biotechnology companies in Japan, Taiwan, and the United States are currently using the machine.

What do you think? Will this device allow companies to explore the feasibility of testing without animals? Or will companies stay with the status quo? Come over to the Biology Forum and share your thoughts, opinions, and feelings. 'Til next time...

Biotechnology in India

The Indian biotechnology sector is one of the fastest growing knowledge-based sectors in India and is expected to play a key role in shaping India's rapidly developing economy. Currently, India holds two per cent share of global market. With numerous comparative advantages in terms of R&D facilities, knowledge, skills, and cost effectiveness, the biotechnology industry in India has immense potential to emerge as a global key player. The Indian biotech market was estimated at US$ 2.80 billion in 2007–08 and is likely grow at a compound annual growth rate (CAGR) of 30 per cent. Going by a forecast in 'Bio Reality in India: Report 2008', by international real estate consultants Cushman & Wakefield, the industry is expected to cross the US$ 5 billion-mark through its products as well as services by 2010. By this time, it is estimated to occupy 140 million square feet of industrial area. According to a report by the Confederation of Indian Industry (CII) and consultancy firm KPMG, the Indian biotechnology sector is likely to become a US$ 5 billion industry by 2010. The report stated, "India is ranked among the top 12 biotech destinations in the world and is the third biggest in Asia-Pacific in terms of the number of biotech companies." The sector has been attracting major investments, which have been growing at the rate of about 38 per cent for the last three years, and had touched US$ 560 million in 2006–07. Leading institutes such as the All India Institutes of Medical Sciences (AIIMS) and Centre for Cellular and Molecular Biology (CCMB) have made noteworthy contributions to this industry. A growing number of Indian biotechnology firms are now providing research and development (R&D) services to global pharma companies. Companies are providing high level services in drug discovery and validation processes, in the fields of pathway analysis (study of effect of toxic or radioactive substances on humans), genomics (study of gene sequences), proteomics (study of proteins) and translational research (investigation and experiments on patients and volunteers). In this context, Kiran Mazumdar-Shaw, Chairman and Managing Director, Biocon group has said, "Co-development agreements are leading to interesting models." Several new innovations and opportunities have recently sprung up in the Indian biotech segment. The UNIDO Centre for South-South Industrial Cooperation (UCSSIC) has acknowledged cashew apple as a substitute to food crops that are currently being used for ethanol production and India is one of the countries being targetted by the UNIDO. India will replace 10 per cent of its transport fuels with biofuels like ethanol and jatropha in the next 10 years to cut carbon emissions. Another step towards maximising energy efficiency is Co-generation - a concept of producing two different forms of energy from one fuel. The bagasse-based co-generation option, which started as a cost-saving measure by sugar companies, is one such profitable option. India is likely to add 1,200 MW bagasse-based power capacities during the 11th Five-Year-Plan. The biomass from bamboo has been found to be a good source of high energy and can be used as green coal, which contains fewer pollutants and is a renewable source of energy. Market Size and the Key Opportunity Segments According to an industry survey, carried out by Association of Biotech Led Enterprises (ABLE), biotechnology industry in India has notched up a growth of 20 per cent during 2007–08 and the revenues earned were worth US$ 2.56 billion as against US$ 2.1 billion during the previous fiscal. Research services touched US$ 500 million and bio-IT (bioinformatics) was US$ 250 million. In 2005–06, the Indian biotechnology industry replicated the previous year's growth rates, with sales growth of 37.42 per cent, touching US$ 1.47 billion in revenues. In the last fiscal, investments increased by 21 per cent at US$ 637,607 million with 48 per cent of the total biotech market shared between the 20 leading Indian companies. As per the findings of the survey, 56 per cent of the sector's revenue (US$ 1.44 billion) came from exports. Around 70 per cent of exports were from bio-pharma and 26 percent from bio-services segments. Further according to the findings, going by the current trend and the new biotech policy of the central government, the sector is poised to generate US$ 13–16 billion by 2015. The Indian bioinformatics market, which deals with creation and maintenance of extensive electronic databases on various biological systems, is set to double by 2010, from US$ 32 million to US$ 62 million by 2010, according to a report by research firm ValueNotes Outsourcing Practice. Out of the five broad categories—biopharma, agri-biotech, bioinformatics, bioindustrial and bioservices—that the biotech industry in India can be divided into, according to the product offerings, the first three are the most important segments according to their revenue contribution. With exports forming a major chunk of the market, India is a significant exporter of bioinformatics and bioservices. The segment derives 90 per cent of its revenue from outsourcing. Since the global bioinformatics market is expected to grow at a CAGR of 16 per cent over 2007–10, it would actually be conducive to its growth in India at a rate of 25 percent. In 2007–08, bio-pharma was the industry's largest sector accounting for almost 70 per cent of the overall revenues and it is likely to touch US$ 4.60 billion by 2012–13. More than 40 per cent of the total 325 biotechnology companies in India are in the biopharma segment. Fuelled by the robust sales of BT cotton, the bio-agriculture sector is one of the fastest growing sectors in the industry. With a well-developed R&D capability and a large patient base for clinical trials, the bioservices sector is another sector with great promise. With strong growth in R&D and production, the bio-supplier industry is also on the growth path.

ELECTRON MICROSCOPES

An electron microscope uses electrons to “illuminate” an object. Electrons have a much smaller wavelength than light, so they can resolve much smaller structures. The smallest wavelength of visible light is about 4000 angstroms (40 millionths of a meter). The wavelength of electrons used in electron microscopes is usually about half an angstrom (50 trillionths of a meter).

Electron microscopes have an electron gun that emits electrons, which then strike the specimen. Conventional lenses used in optical microscopes to focus visible light do not work with electrons; instead, magnetic fields are used to create “lenses” that direct and focus the electrons. Since electrons are easily scattered by air molecules, the interior of an electron microscope must be sealed at a very high vacuum. Electron microscopes also have systems that record or display the images produced by the electrons.

There are two types of electron microscopes: the transmission electron microscope (TEM), and the scanning electron microscope (SEM). In a TEM, the electron beam is directed onto the object to be magnified. Some of the electrons are absorbed or bounce off the specimen, while others pass through and form a magnified image of the specimen. The sample must be cut very thin to be used in a TEM, usually no more than a few thousand angstroms thick. A photographic plate or fluorescent screen beyond the sample records the magnified image. Transmission electron microscopes can magnify an object up to one million times.

In a scanning electron microscope, a tightly focused electron beam moves over the entire sample to create a magnified image of the surface of the object in much the same way an electron beam scans an image onto the screen of atelevision. Electrons in the tightly focused beam might scatter directly off the sample or cause secondary electrons to be emitted from the surface of the sample. These scattered or secondary electrons are collected and counted by an electronic device. Each scanned point on the sample corresponds to a pixel on a television monitor; the more electrons the counting device detects, the brighter the pixel on the monitor is. As the electron beam scans over the entire sample, a complete image of the sample is displayed on the monitor.

An SEM scans the surface of the sample bit by bit, in contrast to a TEM, which looks at a relatively large area of the sample all at once. Samples scanned by an SEM do not need to be thinly sliced, as do TEM specimens, but they must be dehydrated to prevent the secondary electrons emitted from the specimen from being scattered by water molecules in the sample.

Scanning electron microscopes can magnify objects 100,000 times or more. SEMs are particularly useful because, unlike TEMs and powerful optical microscopes, they can produce detailed three-dimensional images of the surface of objects.

The scanning transmission electron microscope (STEM) combines elements of an SEM and a TEM and can resolve single atoms in a sample.

The electron probe microanalyzer, an electron microscope fitted with an X-ray spectrum analyzer, can examine the high-energy X rays emitted by the sample when it is bombarded with electrons. The identity of different atoms or molecules can be determined from their X-ray emissions, so the electron probe analyzer not only provides a magnified image of the sample, but also information about the sample's chemical composition.

OPTICAL MICROSCOPES

The most widely used microscopes are optical microscopes, which use visiblelight to create a magnified image of an object. The simplest optical microscope is the double-convex lens with a short focal length. Double-convex lenses can magnify an object up to 15 times.

The compound microscope uses two lenses, an objective lens and an ocular lens, mounted at opposite ends of a closed tube, to provide greater magnification than is possible with a single lens. The objective lens is composed of several lens elements that form an enlarged real image of the object being examined. The real image formed by the objective lens lies at the focal point of the ocular lens. Thus, the observer looking through the ocular lens sees an enlarged virtual image of the real image. The total magnification of a compound microscope is determined by the focal lengths of the two lens systems and can be more than 2000 times.

Optical microscopes have a firm stand with a flat stage to hold the material examined and some means for moving the microscope tube toward and away from the specimen to bring it into focus. Ordinarily, specimens are transparent and are mounted on slides—thin, rectangular pieces of clear glass that are placed on the stage for viewing. The stage has a small hole through which light can pass from a light source mounted underneath the stage—either a mirror that reflects natural light or a special electric light that directs light through the specimen.

Microbiology

An agar plate streaked withmicroorganisms

Microbiology (from Greek μῑκρος, mīkros, "small"; βίος, bios, "life"; and -λογία, -logia) is the study ofmicroorganisms, which are unicellular or cell-cluster microscopic organisms. This includes eukaryote such as fungi and protists, and prokaryotes, which are bacteria and archaea. Viruses, though not strictly classed as living organisms, are also studied. In short; microbiology refers to the study of life and organisms that are too small to be seen with the naked eye.

Microbiology is a broad term which includes virology, mycology, parasitology, bacteriology and other branches. A microbiologist is a specialist in microbiology.

Microbiology is researched actively, and the field is advancing continually. We have probably only studied about one percent of all of the microbe species on Earth. Although microbes were first observed over three hundred years ago, the field of microbiology can be said to be in its infancy relative to older biological disciplines such as zoology and botany.

Bio fertilizers

One of the major concerns in today's world is the pollution and contamination of soil. The use of chemical fertilizers and pesticides has caused tremendous harm to the environment. An answer to this is the biofertilizer, an environmentally friendly fertilizer now used in most countries. Biofertilizers are organisms that enrich the nutrient quality of soil. The main sources of biofertilizers are bacteria, fungi, and cynobacteria (blue-green algae). The most  striking relationship that these have with plants is symbiosis, in which the partners derive benefits from each other.

Plants have a number of relationships with fungi, bacteria, and algae, the most common of which are with mycorrhiza, rhizobium, and cyanophyceae. These are known to deliver a number of benefits including plant nutrition, disease resistance, and tolerance to adverse soil and climatic conditions. These techniques have proved to be successful biofertilizers that form a health relationship with the roots. 

Biofertilizers will help solve such problems as increased salinity of the soil and chemical run-offs from the agricultural fields. Thus, biofertilizers are important if we are to ensure a healthy future for the generations to come.

Mycorrhiza

Mycorrhizae are a group of fungi that include a number of types based on the different structures formed inside or outside the root. These are specific fungi that match with a number of favourable parameters of the the host plant on which it grows. This includes soil type, the presence of particular chemicals in the soil types, and other conditions.

These fungi grow on the roots of these plants. In fact, seedlings that have mycorrhizal fungi growing on their roots survive better after transplantation and grow faster. The fungal symbiont gets shelter and food from the plant which, in turn, acquires an array of benefits such as better uptake of phosphorus, salinity and drought tolerance, maintenance of water balance, and overall increase in plant growth and development.

While selecting fungi, the right fungi have to be matched with the plant. There are specific fungi for vegetables, fodder crops, flowers, trees, etc.

Mycorrhizal fungi can increase the yield of a plot of land by 30%-40%. It can absorb phosphorus from the soil and pass it on to the plant. Mycorrhizal plants show higher tolerance to high soil temperatures, various soil- and root-borne pathogens, and heavy metal toxicity.

Legume-rhizobium relationship

Leguminous plants require high quantities of nitrogen compared to other plants. Nitrogen is
an inert gas and its uptake is possible only in fixed form, which is facilitated by the rhizobium
bacteria present in the nodules of the root system. The bacterium lives in the soil to form root
nodules (i.e. outgrowth on roots) in plants such as beans, gram, groundnut, and soybean. 


Blue-green algae

Blue-green algae are considered the simplest, living autotrophic plants, i.e. organisms capable of building up food materials from inorganic matter. They are microscopic. Blue-green algae are widely distributed in the aquatic environment. Some of them are responsible for water blooms in stagnant water. They adapt to extreme weather conditions and are found in snow and in hot springs, where the water is 85 °C.

Certain blue-green algae live intimately with other organisms in a symbiotic relationship. Some are associated with the fungi in form of lichens. The ability of blue-green algae tophotosynthesize food and fix atmospheric nitrogen accounts for their symbiotic associations and also for their presence in paddy fields.

Blue-green algae are of immense economic value as they add organic matter to the soil and increase soil fertility. Barren alkaline lands in India have been reclaimed and made productive by inducing the proper growth of certain blue-green algae.

Bt cotton

Cotton and other monocultured crops require an intensive use of pesticides as various types of pests attack these crops causing extensive damage. Over the past 40 years, many pests have developed resistance to pesticides.

So far, the only successful approach to engineering crops for insect tolerance has been the addition of Bt toxin, a family of toxins originally derived from soil bacteria. The Bt toxin contained by the Bt crops is no different from other chemical pesticides, but causes much less damage to the environment. These toxins are effective against a variety of economically important crop pests but pose no hazard to non-target organisms like mammals and fish. Three Bt crops are now commercially available: corn, cotton, and potato.

As of now, cotton is the most popular of the Bt crops: it was planted on about 1.8 million acres (728437 ha) in 1996 and 1997. The Bt gene was isolated and transferred from a bacterium bacillus thurigiensis to American cotton. The American cotton was subsequently crossed with Indian cotton to introduce the gene into native varieties.

The Bt cotton variety contains a foreign gene obtained from bacillus thuringiensis. This bacterial gene, introduced genetically into the cotton seeds, protects the plants from bollworm (A. lepidoptora), a major pest of cotton. The worm feeding on the leaves of a BT cotton plant becomes lethargic and sleepy, thereby causing less damage to the plant.

Field trials have shown that farmers who grew the Bt variety obtained 25%–75% more cotton than those who grew the normal variety. Also, Bt cotton requires only two sprays of chemical pesticide against eight sprays for normal variety. According to the director general of the Indian Council of Agricultural Research, India uses about half of its pesticides on cotton to fight the bollworm menace.

Use of Bt cotton has led to a 3%–27 increase in cotton yield in countries where it is grown.

Genetic engineering

Genetically modified plants are created by the process of genetic engineering, which allows scientists to move genetic material between organisms with the aim of changing their characteristics. All organisms are composed of cells that contain the DNA molecule. Molecules of DNA form units of genetic information, known as genes. Each organism has a genetic blueprint made up of DNA that determines the regulatory functions of its cells and thus the characteristics that make it unique.

Prior to genetic engineering, the exchange of DNA material was possible only between individual organisms of the same species. With the advent of genetic engineering in 1972, scientists have been able to identify specific genes associated with desirable traits in one organism and transfer those genes across species boundaries into another organism. For example, a gene from bacteria, virus, or animal may be transferred into plants to produce genetically modified plants having changed characteristics. Thus, this method allows mixing of the genetic material among species that cannot otherwise breed naturally. The success of a genetically improved plant depends on the ability to grow single modified cells into whole plants. Some plants like potato and tomato grow easily from single cell or plant tissue. Others such as corn, soy bean, and wheat are more difficult to grow.

After years of research, plant specialists have been able to apply their knowledge of genetics to improve various crops such as corn, potato, and cotton. They have to be careful to ensure that the basic characteristics of these new plants are the same as the traditional ones, except for the addition of the improved traits.

The world of biotechnology has always moved fast, and now it is moving even faster. More traits are emerging; more land than ever before is being planted with genetically modified varieties of an ever-expanding number of crops. Research efforts are being made to genetically modify most plants with a high economic value such as cereals, fruits, vegetables, and floriculture and horticulture species.

Public concern

The potential of biotechnology as a method to enhance agricultural productivity in the future has been accepted globally.

However, because of its revolutionary nature, there is a great degree of risk and uncertainty attached to the process of genetic engineering and the resultant genetically modified products.

Risks are also associated with genetically modified plants that are released into the environment. The nature of interactions with other organisms of the natural ecosystems cannot be anticipated without proper scientific testing. For example, modified plants with enhanced resistance to pests or disease threaten to transfer resistance to the wild relatives. This may have implications for biodiversity and ecosystem integrity. These and other numerous doubts plague the minds of common people and the decision-makers.

DNA

Since the time Gregor Mendel began studying about inheritance in garden plants some 150 years back, researchers have worked to learn more about the language of life – how characteristics pass from one generation to another. Researchers began to understand DNA from the 1800s when they stated that all living beings, whether plants, humans, animals, or bacteria, comprised cells that have the same basic components.

Living organism are made up of cells, i.e. cells are the basic units of life. For example, each of us is made up of billions of this basic unit. If one closely inspects the structure of the cell, one is likely to find various smaller bodies or organelles like mitochondria that generates the energy required to perform all life processes (‘the powerhouse’), chloroplast (only in green plants and responsible for their coloration), the central core – ‘the nucleus, to name a few. The nucleus harbours the blueprint of life and the genetic material – DNA or deoxyribonucleic acid – and is the control centre of any cell. The genetic material or the blueprint is contained in all the cells that make up an organism and is transmitted from one generation to another. A child inherits half of the genetic material from each of his/her parents.

The chemical structure of everyone's DNA is the same. Structurally, DNA is a double helix: two strands of genetic material spiraled around each other. Each strand contains a sequence of bases, also called nucleotides. A base is one of four chemicals: adenine, guanine, cytosine, and thymine. The two strands of DNA are connected at each base. Each base will only bond with one other base, as follows: Adenine (A) will only bond with thymine (T), and guanine (G) will only bond with cytosine (C). If one strand of DNA looks like A-A-C-T-G-A-T-A-G-G-T-C-T-A-,the DNA strand bound to it will look like T-T-G-A-C-T-A-T-C-C-A-G-A-T-C.

Together, the section of DNA would be represented as given in Figure

T-T-G-A-C-T-A-T-C-C-A-G-A-T-C

A-A-C-T-G-A-T-A-G-G-T-C-T-A-G

The length of the DNA strand varies from organism to organism but within individuals of a particular species it is nearly constant. For example, a certain virus may have only 50 000 (5 x 10⁴) bases constituting the genetic material whereas a human cell contains nearly 3.2 billion (3.2 x 10⁹) bases in each of the cells (except the germ line cells). The amount and sequence in all the cells of an organism is identical. The DNA is for most part of the time present as condensed body called chromosomes (coloured body) except when it is replicating or dividing. A piece of a chromosome that dictates a particular trait, for example, eye and skin colour in humans, is called a gene. In any cell, the DNA can be classified into two categories – the sequence that codes for traits or genes and the sequence that has no apparent function or the non-coding DNA. The coding sequence (genes) in humans constitutes only five per cent of the total DNA and is identical in all humans. The non-coding sequence, which is nearly 95% in humans, varies from one individual to another, and forms the basis of DNA fingerprinting.

DNA fingerprinting

The only difference between two individuals is the order of the base pairs. Each individual has a different sequence of DNA, specially in the non-coding region. Using these sequences, every person could be identified solely by the sequence of their base pairs. However, because the entire DNA is so huge, the task would be time-consuming and nearly impossible. Instead, scientists are able to use a shorter method.

The steps involved in DNA fingerprinting can be summarized as follows.

	Isolating the DNA in question from the rest of the cellular material in the nucleus.
	Cutting the DNA into several pieces of different sizes.
	Sorting the DNA pieces by size. The process by which the size separation, or ‘size fractionation’, is done is called gel electrophoresis.

This is the basic concept behind fingerprinting technique.

DNA fingerprinting in plants

The concept of DNA fingerprinting can also be extended to plants and many institutions in the country are doing it today. TERI has successfully generated fingerprints of various medicinal plants such as neem, ashwagandha, and amla with the objective of determining their identity. With the help of fingerprints one can find out the genetic diversity in India. This knowledge has profound implications. Based on the extent of genetic diversity, one can establish the centre of origin of a particular plant species. And having done that we are better equipped to prevent bio-piracy or the theft of our genetic resources.

Human Genome project

Human Genome Project

DNA Replication image from the Human Genome Project (HGP)

The Human Genome Project is an initiative of the U.S. Department of Energy (“DOE”) that aims to generate a high-quality reference sequence for the entire human genome and identify all the human genes.

The DOE and its predecessor agencies were assigned by the U.S. Congress to develop new energy resources and technologies and to pursue a deeper understanding of potential health and environmental risks posed by their production and use. In 1986, the DOE announced its Human Genome Initiative. Shortly thereafter, the DOE and National Institutes of Health developed a plan for a joint Human Genome Project (“HGP”), which officially began in 1990.

The HGP was originally planned to last 15 years. However, rapid technological advances and worldwide participation accelerated the completion date to 2003 (making it a 13 year project). Already it has enabled gene hunters to pinpoint genes associated with more than 30 disorders.

Cloning

Cloning involves the removal of the nucleus from one cell and its placement in an unfertilized egg cell whose nucleus has either been deactivated or removed.

There are two types of cloning:

1. Reproductive cloning. After a few divisions, the egg cell is placed into a uterus where it is allowed to develop into a fetus that is genetically identical to the donor of the original nucleus.
2. Therapeutic cloning. The egg is placed into a Petri dish where it develops into embryonic stem cells, which have shown potentials for treating several ailments.

In February 1997, cloning became the focus of media attention when Ian Wilmut and his colleagues at the Roslin Institute announced the successful cloning of a sheep, named Dolly, from the mammary glands of an adult female. The cloning of Dolly made it apparent to many that the techniques used to produce her could someday be used to clone human beings. This stirred a lot of controversy because of its ethical implications.

Genetic testing

Gel electrophoresis

Genetic testing involves the direct examination of the DNA molecule itself. A scientist scans a patient’s DNA sample for mutated sequences.

There are two major types of gene tests. In the first type, a researcher may design short pieces of DNA (“probes”) whose sequences are complementary to the mutated sequences. These probes will seek their complement among the base pairs of an individual’s genome. If the mutated sequence is present in the patient’s genome, the probe will bind to it and flag the mutation. In the second type, a researcher may conduct the gene test by comparing the sequence of DNA bases in a patient’s gene to disease in healthy individuals or their progeny.

Genetic testing is now used for:

• Carrier screening, or the identification of unaffected individuals who carry one copy of a gene for a disease that requires two copies for the disease to manifest;
• Confirmational diagnosis of symptomatic individuals;
• Determining sex;
• Forensic/identity testing;
• Newborn screening;
• Prenatal diagnostic screening;
• Presymptomatic testing for estimating the risk of developing adult-onset cancers;
• Presymptomatic testing for predicting adult-onset disorders.

Some genetic tests are already available, although most of them are used in developed countries. The tests currently available can detect mutations associated with rare genetic disorders like cystic fibrosis, sickle cell anemia, and Huntington’s disease. Recently, tests have been developed to detect mutation for a handful of more complex conditions such as breast, ovarian, and colon cancers. However, gene tests may not detect every mutation associated with a particular condition because many are as yet undiscovered, and the ones they do detect may present different risks to different people and populations.^[12]

[edit]Controversial questions

The bacterium C Villos lada is routinely genetically engineered.

Several issues have been raised regarding the use of genetic testing:

1. Absence of cure. There is still a lack of effective treatment or preventive measures for many diseases and conditions now being diagnosed or predicted using gene tests. Thus, revealing information about risk of a future disease that has no existing cure presents an ethical dilemma for medical practitioners.
2. Ownership and control of genetic information. Who will own and control genetic information, or information about genes, gene products, or inherited characteristics derived from an individual or a group of people like indigenous communities? At the macro level, there is a possibility of a genetic divide, with developing countries that do not have access to medical applications of biotechnology being deprived of benefits accruing from products derived from genes obtained from their own people. Moreover, genetic information can pose a risk for minority population groups as it can lead to group stigmatization.

At the individual level, the absence of privacy and anti-discrimination legal protections in most countries can lead to discrimination in employment or insurance or other misuse of personal genetic information. This raises questions such as whether genetic privacy is different from medical privacy.^[13]

1. Reproductive issues. These include the use of genetic information in reproductive decision-making and the possibility of genetically altering reproductive cells that may be passed on to future generations. For example, germline therapy forever changes the genetic make-up of an individual’s descendants. Thus, any error in technology or judgment may have far-reaching consequences. Ethical issues like designer babies and human cloning have also given rise to controversies between and among scientists and bioethicists, especially in the light of past abuses with eugenics.
2. Clinical issues. These center on the capabilities and limitations of doctors and other health-service providers, people identified with genetic conditions, and the general public in dealing with genetic information.
3. Effects on social institutions. Genetic tests reveal information about individuals and their families. Thus, test results can affect the dynamics within social institutions, particularly the family.
4. Conceptual and philosophical implications regarding human responsibility, free will vis-à-vis genetic determinism, and the concepts of health and disease.