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Biology
Biotechnology and its Applications
86 questions from 37 papers, each with its answer.
- 86 questions
- 37 papers
- 2.44% of Biology
Genetically Engineered Insulin
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Which of the following genetically engineered organisms was used by Eli Lilly to prepare human insulin?
Eli Lilly used Escherichia coli (a bacterium) to produce chains A and B of human insulin.
In 1983, Eli Lilly synthesized DNA sequences corresponding to chains A and B of human insulin and introduced them into plasmids of the bacterium Escherichia coli to produce Humulin. -
The two polypeptides of human insulin are linked together by
Chains A and B of insulin are joined by disulphide bonds.
Insulin is produced by β-cells of the islets of Langerhans as pro-insulin, made of polypeptide chains A and B with a C-peptide. The C-peptide is removed and the A and B chains remain linked by disulphide bridges. -
Which one of the following is now being commercially produced by biotechnological procedures?Human insulin is produced commercially by recombinant DNA technology.
In 1983 Eli Lilly, an American company, prepared two DNA sequences corresponding to the A and B chains of human insulin and introduced them into plasmids of $E.\ coli$ to produce the insulin chains.
Chains A and B were produced separately, extracted and combined by creating disulphide bonds to form human insulin (humulin).
Nicotine, morphine and quinine are plant alkaloids obtained from tobacco, the opium poppy and $Cinchona$ bark respectively.
Hence insulin is the one produced by biotechnological procedures. -
Human insulin is being commercially produced from a transgenic species of:Insulin consists of two short polypeptide chains, chain A and chain B, linked together by disulphide bridges.
In 1983, the American company Eli Lilly prepared two DNA sequences corresponding to the A and B chains of human insulin.
These sequences were introduced into the plasmids of Escherichia coli to produce the insulin chains.
Chains A and B were produced separately, extracted and combined by creating disulphide bonds to form human insulin (humulin).
Rhizobium is a nitrogen-fixing bacterium, Saccharomyces is yeast and Mycobacterium includes disease-causing bacteria; the classical commercial source described in NCERT is the transgenic bacterium Escherichia coli.
So human insulin is commercially produced from a transgenic species of Escherichia.
Applications in Agriculture - Pest Resistance
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Silencing of specific mRNA is possible via RNAi because of -
RNAi uses complementary double-stranded RNA (dsRNA) to silence target mRNA.
RNA interference (RNAi) involves the introduction of double-stranded RNA (dsRNA) matching the target sequence, which is processed by Dicer into siRNAs and incorporated into RISC to cleave complementary mRNA, silencing translation.
Genetically Engineered Insulin Administration
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Why can't insulin be given orally to diabetic patients?
Insulin is a polypeptide hormone that gets proteolytically degraded by gastrointestinal enzymes if ingested orally.
Insulin is a 51-amino-acid peptide hormone. When administered orally, gastric pepsin and pancreatic endopeptidases (trypsin, chymotrypsin) digest it into inactive amino acids before systemic absorption.
Molecular Diagnosis
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A single strand of nucleic acid tagged with a radioactive molecule is calledA probe is a single-stranded DNA or RNA tagged with a radioactive molecule.
It hybridises to its complementary DNA in a clone of cells and is then detected by autoradiography.
A vector carries foreign DNA, and a selectable marker helps to identify transformants. -
DNA or RNA segment tagged with a radioactive molecule is calledA probe is a single-stranded DNA or RNA segment tagged with a radioactive molecule.
It is allowed to hybridise to its complementary DNA in a clone of cells, and the hybrid is then detected by autoradiography.
A clone having a mutated gene does not appear on the photographic film, because the probe is not complementary to the mutated gene.
Probes are also used in DNA fingerprinting (VNTR probes).
A plasmid is an extra-chromosomal circular DNA, a vector carries foreign DNA into a host and a clone is a group of identical cells or DNA copies.
Hence such a tagged segment is called a probe.
Gene Therapy
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When gene targetting involving gene amplification is attempted in an individual's tissue to treat disease, it is known as:
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The adenosine deaminase deficiency results into:
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The first clinical gene therapy was given for treatingThe first clinical gene therapy was given in 1990 to a 4-year-old girl suffering from adenosine deaminase (ADA) deficiency.
ADA is an enzyme essential for the functioning of the immune system; the disorder is caused by deletion of the ADA gene.
Lymphocytes from the patient's blood were grown in culture, a functional ADA cDNA was introduced into them using a retroviral vector, and the cells were returned to the patient.
Diabetes mellitus is treated with insulin, chicken pox is a viral infection and rheumatoid arthritis is an auto-immune disorder; none of them was the first target of gene therapy.
Hence the first clinical gene therapy was for adenosine deaminase deficiency.
Biotechnological Applications in Agriculture – Bt Cotton
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Bt cotton variety that was developed by the introduction of toxin gene of $Bacillus\ thuringiensis$ (Bt) is resistant to:Bt cotton contains $cry$IAc and $cry$IIAb genes from $Bacillus\ thuringiensis$, which protect it from the cotton bollworm. So it is resistant to insect pests (it acts as a biopesticide).
Biotechnological Applications in Agriculture
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Which of the following is true for Golden rice?
Gene transfer, gene therapy and cloning
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Match List - I with List - II. Choose the correct answer.
Pick the matching item from Column II for each row.
Column I
- A. Gene gun
- B. Gene therapy
- C. Gene cloning
- D. Genome
Column II
- I. Replacement of a faulty gene by a normal healthy gene
- II. Used for transfer of Gene
- III. Total DNA in the cells of an organism
- IV. To obtain identical copies of a particular DNA molecule
Correct answer: A → II, B → I, C → IV, D → III
Gene gun is used to transfer DNA into plant cells; gene therapy is the replacement of a defective gene by a functional gene; gene cloning is used to obtain identical copies of a desired gene; the genome is the total DNA content in the cells of an organism.
Transgenic animals
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Milk of transgenic 'Cow Rosie' was nutritionally more balanced product for human babies than natural cow milk because it contained:The transgenic cow Rosie produced milk containing human alpha-lactalbumin, making it nutritionally more balanced for human babies.
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Maximum number of existing transgenic animals is ofAnimals whose DNA has been manipulated to possess and express an extra (foreign) gene are called transgenic animals.
Transgenic rats, rabbits, pigs, sheep, cows and fish have been produced.
However, over 95 per cent of all existing transgenic animals are mice.
Mice are preferred because they are small, breed quickly and their genetics is well known.
Hence the maximum number of existing transgenic animals is of mice. -
A giant rat is formed in the laboratory, what is the reason :In 1982, scientists produced giant mice ('supermice') by introducing the rat growth hormone gene into fertilised mouse eggs. The transgenic animals made extra growth hormone and grew almost twice the normal size.
This was done by gene manipulation (recombinant DNA technology / genetic engineering).
So the giant rat (mouse) was formed by gene manipulation.
Ethical issues - biopiracy
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Exploitation of bioresources of a nation by multinational companies without authorization from the concerned country is referred to as
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Use of bioresources by multinational companies and organisations without authorisation from the concerned country and its people is called
Unauthorised use of bioresources without compensation is biopiracy.
Biopiracy is the term used to refer to the use of bioresources by multinational companies and other organisations without proper authorisation from the countries and people concerned, without compensatory payment (NCERT definition).
RNA interference
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In RNAi, the genes are silenced using:
Bt crops - cry proteins
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The inactive form of Bt toxin is converted to the active form in the insect gut _______Reference: NCERT Class XII, pages 179 –.
Gene therapy – vectors
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Which of the following is commonly used as a vector for introducing a DNA fragment in human lymphocytes?
Retroviral vectors are used in gene therapy (e.g. ADA deficiency).
Retrovirus is commonly used as a vector for introducing a DNA fragment in human lymphocytes. Gene therapy: lymphocytes from the blood of the patient are grown in culture outside the body, and a functional gene is introduced into these lymphocytes using a retroviral vector.
Ethical issues – GEAC
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In India, the organisation responsible for assessing the safety of introducing genetically modified organisms for public use is
GEAC appraises the safety of GM organisms in India.
The Indian Government has set up organisations such as GEAC (Genetic Engineering Appraisal Committee), which make decisions regarding the validity of GM research and the safety of introducing GM organisms for public services (direct from NCERT).
Biopiracy – Basmati patent
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A 'new' variety of rice was patented by a foreign company, though such varieties have been present in India for a long time. This is related to
The Basmati patent case is a classic example of biopiracy.
In 1997, an American company got patent rights on Basmati rice through the US Patent and Trademark Office that was actually derived from Indian farmers' varieties. The diversity of rice in India is one of the richest in the world; 27 documented varieties of Basmati are grown in India. Indian Basmati was crossed with semi-dwarf varieties and claimed as an invention or a novelty. Sharbati Sonora and Lerma Rojo are varieties of wheat.
RNA interference – nematode resistance
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Which part of the tobacco plant is infected by $Meloidogyne\ incognita$?
The root-knot nematode attacks roots.
$Meloidogyne\ incognita$ is a nematode parasite that infects the roots of tobacco plants and severely reduces yield. RNA interference is used to prevent this infestation.
Gene therapy – ADA deficiency
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Which kind of therapy was given in 1990 to a four year old girl with adenosine deaminase (ADA) deficiency?
Biosafety issues
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Which body of the Government of India regulates GM research and safety of introducing GM organisms for public services?The Genetic Engineering Approval Committee (GEAC) regulates GM research and the safety of introducing GM organisms for public services.
Bt cotton
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In Bt cotton, the Bt toxin present in plant tissue as pro-toxin is converted into active toxin due toBacillus thuringiensis forms Cry protein crystals in an inactive protoxin form.
The alkaline pH of the insect gut solubilises the crystals and converts the protoxin into the active toxin. -
Some of the characteristics of Bt cotton areBt cotton carries cry genes from $Bacillus\ thuringiensis$; the proteins encoded by the genes cryIAc and cryIIAb control the cotton bollworms.
Because the crop is protected from bollworms, the loss is reduced and the yield is high, with less use of insecticide.
The toxin is specific: Bt toxins are insect-group specific, and those in Bt cotton act on lepidopteran bollworms, not on aphids, beetles or dipterans (flies and mosquitoes).
(The protein encoded by cryIAb controls the corn borer.)
Hence Bt cotton shows high yield and resistance to bollworms.
Transgenic crops
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The crops engineered for glyphosate are resistant/tolerant toGlyphosate is a herbicide; crops engineered for glyphosate tolerate the herbicide, so it kills the surrounding weeds without harming the crop.
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Golden rice is a genetically modified crop plant where the incorporated gene is meant for biosynthesis of:
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Consumption of which one of the following foods can prevent the kind of blindness associated with vitamin 'A' deficiency?Golden rice is a genetically modified rice that carries genes for the synthesis of β-carotene (provitamin A) in the grain.
Eating it supplies vitamin A and can prevent night blindness caused by its deficiency.
Bt-brinjal is insect resistant and Flavr Savr tomato has delayed ripening.
Biotechnology in medicine
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The first human hormone produced by recombinant DNA technology is:Human insulin (Humulin) was the first human hormone made by recombinant DNA technology, by Eli Lilly in 1983.
Bt crops
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Which of the following Bt crops is being grown in India by the farmers?Bt cotton is the Bt crop grown by farmers in India; it resists bollworms.
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The genetically-modified (GM) brinjal in India has been developed forGM brinjal is Bt brinjal: it carries a cry gene from the soil bacterium $Bacillus\ thuringiensis$.
The gene makes the plant produce the Bt toxin protein, which is activated in the alkaline gut of the insect and kills it by creating pores in the midgut epithelial cells.
Bt brinjal was developed for resistance against insect pests such as the fruit and shoot borer, thereby reducing the use of insecticides.
Hence GM brinjal has been developed for insect-resistance. -
The bacterium $Bacillus\ thuringiensis$ is widely used in contemporary biology asSome strains of $Bacillus\ thuringiensis$ produce protein crystals containing a toxic insecticidal protein (Bt toxin) that kills certain insects such as lepidopterans (tobacco budworm, armyworm), coleopterans (beetles) and dipterans (flies, mosquitoes).
Dried spores of the bacterium are sprayed on crops as a bioinsecticide.
The Bt toxin (cry) genes have also been introduced into crop plants such as cotton, corn, rice, tomato, potato and soyabean to make them insect resistant.
Hence $Bacillus\ thuringiensis$ is widely used as an insecticide. -
What is true about Bt toxin?The Bt toxin protein exists in the bacterium as an inactive protoxin (crystals), which is why it does not kill the $Bacillus$ itself; the bacterium has no antitoxin.
Once an insect ingests the inactive toxin, the crystals are solubilised by the alkaline pH of its gut and the protoxin is converted into the active form.
The activated toxin binds to the surface of the midgut epithelial cells and creates pores, which cause cell swelling and lysis and eventually the death of the insect.
It does not act on the ovaries or sterilise the pest.
Hence the true statement is that the inactive protoxin gets converted into the active form in the insect gut. -
Cry1 endotoxins obtained from Bacillus thuringiensis are effective against:Bacillus thuringiensis produces insecticidal protein crystals during a particular phase of its growth. The toxin is coded by a gene named cry.
The protein exists as an inactive protoxin. In the alkaline pH of the insect gut it is solubilised and activated; it then binds to the midgut epithelial cells and creates pores, causing swelling, lysis and death of the insect.
There are a number of cry genes, and the toxins they code for are specific to particular groups of insects.
The proteins encoded by the genes cryIAc and cryIIAb control the cotton bollworms, and that of cryIAb controls the corn borer. These are lepidopteran insects.
Other Bt toxins act on dipterans (flies and mosquitoes) and coleopterans (beetles), but the Cry1 group is specific for lepidopterans such as bollworms.
So Cry1 endotoxins are effective against boll worms. -
Bacillus thuringiensis (Bt) strains have been used for designing novel -Bacillus thuringiensis produces crystalline proteins (Cry proteins) that are toxic to certain insects.
The toxin exists as an inactive protoxin; in the alkaline gut of the insect it becomes active, binds to the midgut cells and creates pores, killing the insect.
The cry genes coding for these proteins have been isolated and introduced into crop plants such as cotton, corn and brinjal.
Such Bt plants produce the toxin themselves and are protected from pests like bollworms and corn borers; they are bioinsecticidal (insect-resistant) plants.
This reduces the need for chemical insecticides.
So Bt strains have been used for designing novel bioinsecticidal plants.
Pest resistant plants
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Silencing of mRNA has been used in producing transgenic plants resistant toSilencing of a specific mRNA by a complementary double-stranded RNA is called RNA interference (RNAi).
The nematode $Meloidogyne\ incognita$ infects the roots of tobacco plants and reduces the yield.
Using $Agrobacterium$ vectors, nematode-specific genes were introduced into the host so that both sense and anti-sense RNA were produced; these formed dsRNA that silenced the specific mRNA of the nematode.
The parasite could not survive in such a transgenic host.
Resistance to bollworms was obtained with Bt toxin genes (cry genes), not by mRNA silencing.
Hence mRNA silencing has been used to produce plants resistant to nematodes. -
The process of RNA interference has been used in the development of plants resistant toThe nematode $Meloidogyne\ incognita$ infects the roots of tobacco plants and greatly reduces the yield.
Using $Agrobacterium$ vectors, nematode-specific genes were introduced into the host plant in such a way that both sense and anti-sense RNA were produced in the host cells.
These complementary RNAs formed double-stranded RNA, which initiated RNA interference (RNAi) and silenced the specific mRNA of the nematode.
The parasite could not survive in the transgenic host, so the plant was protected.
Resistance to insects was obtained by a different method, the Bt toxin genes.
Hence RNA interference has been used to develop plants resistant to nematodes.
Genetically modified crops
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An improved variety of transgenic basmati riceGenetic modification has been used to enhance the nutritional value of food.
Golden rice is a transgenic rice in which genes for β-carotene (provitamin A) synthesis have been introduced; the grains are yellow and rich in vitamin A, which helps to prevent vitamin A deficiency and blindness.
No transgenic variety is completely resistant to all pests and diseases, or grows without any fertiliser.
Hence the improved transgenic rice gives high yield and is rich in vitamin A. -
A transgenic food crop which may help in solving the problem of night-blindness in developing countries is:Night-blindness is caused by the deficiency of vitamin A (retinol), which is needed to form the visual pigment rhodopsin.
Golden rice is a transgenic variety of rice (Oryza sativa) that contains genes for the biosynthesis of $\beta$-carotene (provitamin A) in the endosperm.
The $\beta$-carotene gives the grains a golden yellow colour and is converted into vitamin A in the human body.
Since rice is the staple food in many developing countries, golden rice can help in solving the problem of vitamin A deficiency and night-blindness.
Bt soybean and Starlink maize are insect-resistant crops carrying Bt toxin genes, and Flavr Savr tomato has a longer shelf life due to delayed softening.
So the transgenic food crop is golden rice. -
Golden rice is a promising transgenic crop. When released for cultivation, it will help inGolden rice is a transgenic variety of rice (Oryza sativa) developed by Ingo Potrykus and Peter Beyer.
Genes for the biosynthesis of $\beta$-carotene (provitamin A), taken from daffodil and a bacterium, were introduced so that $\beta$-carotene is produced in the endosperm of the grain.
The $\beta$-carotene gives the grains a golden yellow colour, and it is converted into vitamin A in the human body.
Rice is the staple food of a large population in which vitamin A deficiency causes night blindness and xerophthalmia in children.
So golden rice will help in the alleviation of vitamin A deficiency.
It has not been engineered for pest resistance (as Bt crops are), herbicide tolerance or fuel production. -
Golden rice is a transgenic crop of the future with the following improved trait -Golden rice is a genetically modified variety of rice developed to fight vitamin A deficiency.
Genes for the synthesis of $\beta$-carotene (provitamin A) were introduced into rice, so that $\beta$-carotene is produced in the endosperm.
The grains have a golden yellow colour, and the $\beta$-carotene is converted into vitamin A in the body.
It can help to reduce night blindness and other vitamin A deficiency disorders in regions where rice is the staple food.
It has not been modified for protein or lysine content or for insect resistance.
So the improved trait of golden rice is a high vitamin A content.
Genetically modified organisms
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Transgenic plants are the onesOrganisms whose genes have been altered by manipulation are called genetically modified or transgenic organisms.
A transgenic plant is produced by introducing a foreign gene (DNA) into a plant cell, by a vector such as the Ti plasmid or by a direct method, and then regenerating a whole plant from that transformed cell by tissue culture.
Every cell of such a plant carries and expresses the foreign gene.
Plants raised from somatic embryos are somaclones, and plants produced after protoplast fusion are somatic hybrids; neither contains foreign DNA introduced by genetic engineering.
Hence transgenic plants are those generated by introducing foreign DNA into a cell and regenerating a plant from that cell.
Genetically Engineered Microbes
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A genetically engineered micro-organism used successfully in bioremediation of oil spills is a species ofBioremediation is the use of living organisms, mainly microbes, to remove pollutants from the environment.
Pseudomonas putida was genetically engineered by the Indian-born scientist Ananda Mohan Chakrabarty and is popularly called the 'superbug'.
Plasmids carrying genes for the breakdown of different hydrocarbons (such as octane, xylene, camphor and naphthalene) were brought together in a single strain.
This strain can degrade the various hydrocarbons present in crude oil, so it is used to clear oil spills.
It was also the first genetically engineered organism to be patented.
Trichoderma is a fungus used as a biocontrol agent, Xanthomonas is a plant pathogen and Bacillus thuringiensis is the source of Bt toxin.
So the micro-organism is a species of Pseudomonas.
Recombinant Proteins
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Production of a human protein in bacteria by genetic engineering is possible becauseThe genetic code is universal: the same codon specifies the same amino acid in almost all organisms, from bacteria to humans.
So when a human gene (usually as cDNA, without introns) is introduced into a bacterium with suitable regulatory sequences, the bacterial ribosomes read its codons in the same way and produce the same human protein.
This is how human insulin, human growth hormone and other proteins are produced in E. coli.
Bacteria cannot carry out RNA splicing, which is why cDNA has to be used.
Gene regulation in bacteria and humans is not identical, and human chromosomes cannot replicate in bacterial cells; the gene must be carried on a vector such as a plasmid.
So it is possible because the genetic code is universal.
Molecular Diagnosis: ELISA
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ELISA is used to detect viruses where the key reagent is : -ELISA (Enzyme Linked Immuno-Sorbent Assay) is based on the antigen-antibody reaction. It detects viral antigens or the antibodies formed against the virus (e.g. HIV).
The detecting antibody is linked to an enzyme. After washing, a colourless substrate is added and the enzyme converts it into a coloured product, showing a positive result.
The enzymes commonly used are alkaline phosphatase and horseradish peroxidase.
DNA probes are used in hybridisation tests, not ELISA.
So in ELISA the key reagent is alkaline phosphatase.
Biosafety and Ethical Issues
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Introduction of food plants developed by genetic engineering is not desirable because -Genetically modified (GM) food crops raise biosafety concerns.
The introduced genes or their products may cause allergic reactions or be toxic to humans and animals; viral sequences used in vectors or promoters could give rise to new viruses; and genes may spread to wild relatives.
So there is a danger of viruses, allergens and toxins coming with the introduced crop. This is why GM crops are tested and regulated (in India by GEAC).
So introduction of genetically engineered food plants is considered not desirable because of the danger of viruses, allergens and toxins.
Cloning
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First cloned animal :Dolly the sheep, born in 1996 at the Roslin Institute in Scotland (Ian Wilmut), was the first mammal cloned from an adult somatic cell by nuclear transfer.
Polly was a later transgenic cloned sheep.
So the first cloned animal (mammal) was Dolly the sheep.
That is every question in Biotechnology and its Applications for this filter.
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