Answer

(d) Bt cotton is a genetically modified plant whose genes have been altered by the manipulations to make it insect resistant through the introduction of $B t$ toxin gene.

$B t$ toxin is produced by a bacterium called Bacillus thuringiensis ( $B t$ ). Bt toxin gene has been cloned from the bacteria which is expressed in plants to provide resistance to insects.

Some strains of Bacillus thuringiensis produce proteins that kills certain insects like lepidopterans (tobacco budworm, armyworm), coleopterans (beetles) and dipterans (flies, mosquitoes).

Bt cotton is made resistant to certain taxa of pests only (as mentioned above). It is quite likely that in future, some other pests may infest these Bt cotton plants.

• (a) Bt cotton is indeed a genetically modified (GM) plant because its genes have been altered through genetic engineering to express the Bt toxin gene.
• (b) Bt cotton is insect resistant because it produces the Bt toxin, which is effective against certain insects.
• (c) Bt cotton is a bacterial gene expressing system because it expresses the Bt toxin gene derived from the bacterium Bacillus thuringiensis.

Thinking Process

Mature functional insulin is obtained by the processing of pro-hormone, which contains extra peptide called C-peptide.

Answer

(c) The connecting peptide or C-peptide is a short protein containing 31 amino acids. It connects the $A$ and $B$ chain of proinsulin molecule. After the processing of proinsulin molecule, $C$-peptide is removed leaving behind $A$ and $B$ chains which bound together by disulphide bonds to constitute a insulin molecule.

• (a) A part of mature insulin molecule: This is incorrect because the C-peptide is not part of the mature insulin molecule. It is removed during the maturation process, leaving only the A and B chains in the mature insulin.

• (b) Responsible for the formation of disulphide bridges: This is incorrect because the formation of disulphide bridges occurs between the A and B chains of insulin, not involving the C-peptide. The C-peptide’s role is to connect the A and B chains in the proinsulin molecule before it is removed.

• (d) Responsible for its biological activity: This is incorrect because the biological activity of insulin is due to the A and B chains. The C-peptide does not contribute to the biological activity of insulin; it is simply a byproduct of the maturation process.

Answer

(c) GEAC stands for Genetic Engineering Approval Committee. The Indian government has set up this organisation to make decisions regarding the validity of GM research and the safety of introducing GM-organisms for public services.

• (a) Genome Engineering Action Committee: This option is incorrect because there is no such committee named Genome Engineering Action Committee. The correct term is Genetic Engineering Approval Committee, which specifically deals with the approval and regulation of genetic engineering activities in India.

• (b) Ground Environment Action Committee: This option is incorrect because it does not relate to genetic engineering. The Ground Environment Action Committee would imply a focus on environmental issues related to the ground or soil, which is not the mandate of the GEAC.

• (d) Genetic and Environment Approval Committee: This option is incorrect because it inaccurately combines genetic and environmental aspects. The GEAC specifically focuses on genetic engineering and its approval, not on environmental issues broadly.

Answer

(d) $\alpha$-antitrypsin is a protease inhibitor that is produced by the introduction of specific sequence of DNA (or genes) which codes for a particular product in the transgenic animals. It is used to treat emphysema as it inhibits the enzymes of inflammatory cells that contributes to the respiratory complications.

• (a) Antitrypsin is not an antacid. Antacids are substances that neutralize stomach acidity and are used to relieve heartburn, indigestion, or an upset stomach.
• (b) Antitrypsin is not an enzyme. It is a protease inhibitor, which means it inhibits the activity of certain enzymes, specifically proteases.
• (c) Antitrypsin is not used to treat arthritis. Arthritis treatments typically involve anti-inflammatory medications, pain relievers, and other therapies that target joint inflammation and pain.

Answer

(c) A probe is a single stranded DNA or RNA tagged with a radioactive molecule. It is used to detect the complementary sequences by hybridisation techniques.

• Option (a) is incorrect because while a single stranded RNA can be used as a probe, the option does not account for the possibility of using single stranded DNA, which is also a valid probe.

• Option (b) is incorrect because while a single stranded DNA can be used as a probe, the option does not account for the possibility of using single stranded RNA, which is also a valid probe.

• Option (d) is incorrect because it incorrectly states that a probe can be single stranded DNA but not single stranded RNA, whereas in reality, both single stranded DNA and RNA can be used as probes.

Thinking Process

HIV is the most common example of retrovirus.

Answer

(a) A retrovirus is a single-stranded RNA virus that stores its nucleic acid in the form of mRNA genome (5’cap and 3’poly A tail).

In most viruses, DNA is transcribed into RNA, and then RNA is translated into protein However, in retroviruses their RNA is reverse-transcribed into DNA, which is integrated into the host cell’s genome (when it becomes a provirus) and then undergoes the usual transcription and translational process to express the genes carried by the virus, i.e.

RNA $\rightarrow$ DNA $\rightarrow$ RNA $\rightarrow$ Polypeptide.

• (b) A DNA virus that can synthesize RNA during infection: This option is incorrect because retroviruses are RNA viruses, not DNA viruses. Retroviruses have RNA as their genetic material, which is reverse-transcribed into DNA after infection.

• (c) A ssDNA virus: This option is incorrect because retroviruses have single-stranded RNA (ssRNA) as their genetic material, not single-stranded DNA (ssDNA).

• (d) A dsRNA virus: This option is incorrect because retroviruses have single-stranded RNA (ssRNA) as their genetic material, not double-stranded RNA (dsRNA).

Answer

(b) ADA gene is responsible for producing the enzyme adenosine deaminase. Which is primarily involved in the development and maintenance of immune system.

It is produced in all cells, but the highest level of adenosine deaminase occurs in the cells of immune system called lymphocytes, which develop in lymphoid tissues. ADA converts deoxyadenosine (toxic to lymphocytes ) to deoxyinosine (non-toxic form).

• (a) erythrocytes: Erythrocytes, or red blood cells, primarily function to transport oxygen and carbon dioxide in the blood. They do not play a significant role in the production of adenosine deaminase (ADA), which is more crucial for the immune system.

• (c) blood plasma: Blood plasma is the liquid component of blood that carries cells and proteins throughout the body. While it contains various enzymes and proteins, it is not a primary site for the production of adenosine deaminase (ADA), which is produced within cells, particularly lymphocytes.

• (d) osteocytes: Osteocytes are bone cells that are involved in the maintenance and turnover of bone tissue. They are not involved in the production of adenosine deaminase (ADA), which is primarily associated with the immune system and produced in higher levels in lymphocytes.

Answer

(d) A protoxin is an inactive toxin. The word ‘pro’ in protoxin signifies ‘inactive form’ B. thuringiensis forms protein crystal is which contain a toxic insecticidal protein (Bt toxin).

Bt toxins are initially inactive protoxins but once ingested by insect, the inactive toxin gets converted into an active form due to the alkaline $\mathrm{pH}$ of the gut which solubilises the crystals.

• (a) A primitive toxin: The term “primitive” refers to something ancient or early in the evolutionary scale, which does not align with the definition of a protoxin. A protoxin specifically refers to an inactive form of a toxin, not an ancient or primitive one.

• (b) A denatured toxin: Denatured toxins are toxins that have lost their functional shape due to external factors such as heat or chemicals. This is different from a protoxin, which is an inactive precursor that can become active under certain conditions, rather than being a damaged or altered toxin.

• (c) Toxin produced by Protozoa: Protoxins are not specifically related to protozoa. The term “protoxin” refers to the inactive form of a toxin, regardless of the organism that produces it. Protozoa can produce toxins, but the term protoxin is not exclusive to them.

Answer

(c) Pathophysiology is the study of functional changes in the body of the host that occur in response to any disease or injury.

e.g., if someone ingests a toxin, it may result into a variety of physical changes, such as inflammation in the stomach lining.

• (a) The study of physiology of pathogens is known as “pathogen physiology,” not pathophysiology. Pathophysiology specifically refers to the changes in the host’s body due to disease or injury.

• (b) The study of normal physiology of the host is simply called “physiology,” which focuses on the normal functioning of the body systems, not the altered states caused by disease or injury.

• (d) “None of these” is incorrect because option (c) correctly defines pathophysiology as the study of altered physiology of the host due to disease or injury.

Answer

(c) Bt toxins are initially inactive protoxins but after ingestion by the insect these inactive toxin becomes active due to the alkaline $\mathrm{pH}$ of the gut which solublise the crystals. Hence, high $\mathrm{pH}$ value is required to make $B t$ toxins active. Under high temperature and acidic $\mathrm{pH}, \mathrm{Bt}$ toxins remain insoluble and inactive.

• (a) acidic $\mathrm{pH}$ of stomach: Bt toxins remain insoluble and inactive under acidic conditions, so an acidic $\mathrm{pH}$ of the stomach does not trigger the activation of the toxin.

• (b) high temperature: High temperature does not solubilize the Bt toxin crystals or activate the protoxins. The activation is specifically due to the alkaline $\mathrm{pH}$ of the insect gut.

• (d) mechanical action in the insect gut: Mechanical action alone in the insect gut does not activate the Bt toxins. The activation is primarily due to the alkaline $\mathrm{pH}$ which solubilizes the crystals and activates the protoxins.

Answer

(c) Golden rice is a genetically modified crop with enhanced nutritional value. It is rich in vitamin-A, $\beta$-carotene and was developed at Swiss Federal Institute of Technology. It contains ’ $\beta$ carotene’ gene from daffodil plant and also genes from some bacteria. Golden rice prevents child blindness which is caused due to the deficiency of vitamin-A.

• (a) Golden rice is not a variety of rice grown along the yellow river in China. It is a genetically modified crop developed to address vitamin-A deficiency.
• (b) Golden rice is not long stored rice having a yellow color tint. Its yellow color comes from the presence of $\beta$-carotene, not from storage.
• (d) Golden rice is not a wild variety of rice with yellow-colored grains. It is a transgenic rice specifically engineered to contain $\beta$-carotene.

Thinking Process

RNA interference (RNAi) process is used to produce pest resistant plants.

Answer

(c) A nematode Meloidegyne incognitia infects the roots of tobacco plants which reduces the production of tobacco. It can be prevented by using RNA interference process, which is checked by silencing of specific mRNA due to a complementary dsRNA. dsRNA binds and prevents the translation of $m$ RNA (silencing).

• (a) SS DNA: Single-stranded DNA (SS DNA) does not participate in the RNA interference (RNAi) process. RNAi specifically involves RNA molecules, not DNA.

• (b) $d s$ DNA: Double-stranded DNA (ds DNA) is not involved in RNA interference. RNAi mechanisms rely on RNA molecules, particularly double-stranded RNA (dsRNA), to silence genes.

• (d) SS RNA: Single-stranded RNA (SS RNA) is not sufficient for RNA interference. RNAi requires double-stranded RNA (dsRNA) to effectively bind to and silence the target mRNA.

Answer

(d) The first clinical gene therapy was done for the treatment of SCID (Severe Combined Immuno Deficiency) resulting from the deficiency of ADA.

The SCID patient has a defective gene for the enzyme Adenosine Deaminase (ADA) due to which he/she lacks functional T-lymphocytes and therefore, fails to fight the infecting pathogen.

• (a) AIDS: Gene therapy has not been primarily used for the treatment of AIDS. Instead, treatments for AIDS have focused on antiretroviral therapy (ART) to manage the virus and prevent its progression to AIDS.

• (b) Cancer: While gene therapy is being researched and used in some experimental treatments for cancer, it was not the first condition to be treated with clinical gene therapy. Traditional treatments like surgery, chemotherapy, and radiation therapy have been more commonly used.

• (c) Cystic fibrosis: Although gene therapy is a promising area of research for cystic fibrosis, it was not the first condition to be treated with clinical gene therapy. Treatments for cystic fibrosis have typically included medications, physical therapy, and other supportive measures to manage symptoms and improve quality of life.

Answer

(b) ADA is an enzyme which is deficient in a genetic disorder SCID. ADA stands for adenosine deaminase. This enzyme is crucial for the immune system to function.

• (a) Adenosine Deoxy Aminase: This is incorrect because the correct enzyme name is “adenosine deaminase,” not “adenosine deoxy aminase.” The term “deoxy” is not relevant to the enzyme’s function or structure.

• (c) Aspartate Deaminase: This is incorrect because aspartate deaminase is a different enzyme that acts on aspartate, not adenosine. ADA specifically refers to the enzyme that deaminates adenosine.

• (d) Arginine Deaminase: This is incorrect because arginine deaminase is an enzyme that acts on arginine, not adenosine. ADA specifically refers to the enzyme that deaminates adenosine.

Thinking Process

Gene silencing is a molecular process involved in the down regulation of specific genes and is used as a genetic defense system against viruses and other, organisms

Answer

(c) Gene silencing could be achieved through various routes including the use of RNAi, antisense RNA, ribozymes, etc. All these mechanisms interrupts or suppresses the expression of genes at transcriptional or translational level.

• (a) short interfering RNA (RNAi) only: This option is incorrect because while RNAi is indeed a method for gene silencing, it is not the only method. Other methods such as antisense RNA and ribozymes can also achieve gene silencing.

• (b) antisense RNA only: This option is incorrect because antisense RNA is just one of the methods for gene silencing. RNAi and other mechanisms like ribozymes can also be used to silence genes.

• (d) None of these: This option is incorrect because both RNAi and antisense RNA are valid methods for gene silencing. Therefore, the statement that none of the options can achieve gene silencing is false.

Answer

Major limitations of the earlier green revolution are as follows

(i) Generally undesired characters also breed along with desired ones

(ii) Regular use of fertilisers affected both soil fertility and quality.

(iii) Extensive use of pesticides/insecticides/weedicides resulted in harmful effects on the natural components of the ecosystem.

So, another green revolution that can curb these problems and enhance the quality food production in limited land resources is certainly required.

Answer

GMO stands for Genetically Modified Organism that contains one or more genes from an entirely different species and is genetically altered during molecular genetics such as gene cloning, protein engineering etc.

On the other hand, hybrids contains the recombinant genome of different alleles present in the population of the same species,

Answer

A diagnostic technique helps us to identify a disease. e.g., ELISA for HIV. A therapeutic agent on the other hand helps in the treatment of a disease. e.g., antibiotics for bacterial infections

Answer

ELISA stands for Enzyme Linked Immuno Sorbent Assay. It is used for the detection of (HIV) AIDS disease.

ELISA is based on the principle of antigen-antibody interaction. Infection by pathogen can be detected by the presence of antigens (proteins, glycoprotieins, etc.) or by detecting the antibodies synthesised by the host against the pathogen.

Answer

When the symptoms of the disease are not yet visible,the pathogen concentration is very low so, the detection by conventional diagnostic tests is very difficult.

However, detection of a disease before the appearance of symptoms is possible by the amplification of victim’s nucleic acid by PCR.

The principle involved here is that a single DNA molecule can be copied endlessly in a test tube using primers, DNA polymerase enzyme and free nucleotides. The desired DNA of the pathogen is amplified by PCR from a limited amount of DNA template.

Answer

Biopiracy is the term used to refer the use of bio-resources by the multinational companies and other organisations without proper authorisation from the countries and from the people concerned without compensatory payment.

Most of the industrialised nations are rich financially but poor in biodiversity and traditional knowledge. In contrast, the developing and the underdeveloped world is rich in biodiversity and traditional knowledge related to bio-resources.

So, sometimes industrialised nations tend to exploit the resources or biodiversity of developing nations, for their own advantages.

Answer

Many proteins including certain toxins are secreted in their inactive form. They get activated only when exposed to a specific trigger ( $\mathrm{pH}$, temperature etc.). This mechanism is advantageous to the organism (e.g., bacteria) producing the toxins, as the bacteria does not get killed by the action of proteins present in the toxin.

Answer

Genetic modification of organisms can have unpredictable results when such organisms are introduced into the ecosystem. Because the real effects of gene manipulation are visible only when such organisms interact with other components and organisms of the ecosystem.

Answer

Amendments to the patent bill has empowered India to prevent unauthorised exploitation of our bio-resources and traditional knowledge by other countries. This bill also considers patent terms and initiated research development in this field.

Answer

The patent on Basmati should not have gone to an American Company, because of the following reasons

(i) The Basmati rice variety has been grown in India since time immemorial. Traditionally, it belongs to India.

(ii) The new variety of Basmati that got patent rights to an American Company is actually derived from ‘Indian farmers variety’.

Answer

Insulin is used for diabetes treatment and it was earlier extracted from the pancreas of slaughtered cattle and pigs.

This insulin caused some patients to develop allergy or other types of reactions to the foreign protein.

Answer

Transgenic animals are important in the following fields

(i) They are being used in basic science research to elucidate, the role of genes in the development of diseases like cancer, cystic fibrosis, rheumatoid arthritis and alzheimer’s.

(ii) They are valuable tools in the drug development process itself.

(iii) They can produce medicines or human proteins (insulin, growth hormone, etc.) in large quantities.

(iv) Transgenics can be a source of transplant organs as well.

Answer

Rosie was the name of first transgenic cow. Gene for human alpha lactalbumin was introduced in its genes, which made the milk nutritionally more balanced than normal cow milk.

Answer

PCR is a very sensitive technique which enables the amplification of desired DNA from a limited amount of DNA template.

Hence, it can detect the presence of an infectious organism in the infected patient at an early stage of infection (even before the infectious organism has multiplied to large number).

Answer

GEAC (Genetic Engineering Approval Committee) is an Indian Government Organisation. Its objectives include

(i) Examine the validity of Genetic Modification (GM) of organism research.

(ii) Inspect the safety of introducing GMO for public services.

Answer

Indian Basmati rice was crossed with semi-dwarf variety and was claimed as a new variety for which the patent was field by a USA company.

Answer

Advantages of GMO are

(i) GMO food crops have shorter growing cycles, greater resistance to both insects and diseases, higher yields and higher nutritional value.

(ii) GMO animals have increased production and nutritive values, e.g., GM, cows may produce more milk.

(iii) The World Health Organisation or WHO, claims that GMO plants and animals may allow food prices to drop as food sources become more abundant.

Answer

RNAi technology is used to block the expression of certain genes and also referred to as gene silencing. During this process, a complementary RNA to the mRNA being produced by the gene is introduced into the cell. This RNA binds to the mRNA making it double stranded and therefore, stops the process of translation.

e.g., a nematode Meloidegyne incognitia infects the roots of tobacco plants which reduces the production of tobacco.

It can be prevented by using RNA interference (RNAi) process which is checked by silencing of specific $m R N A$ due to a complementary dsRNA.

dsRNA binds and prevents the translation of mRNA (silencing). By using Agrobacterium vectors, Nematode-specific genes were introduced into the host plants which produces both sense and anti-sense RNA in the host cells.

These two RNAs are complementary to each other and form a double-stranded RNA (dsRNA) that initiates RNAi and hence, silence the specific mRNA of the nematode. The parasite cannot survive in transgenic host and so prevents the plants from pests.

Answer

Human communities have always generated, refined and passed on the knowledge from generation to generation. Such knowledge is called traditional knowledge and is often an important part of the cultural identities. A number of cases relating to traditional knowledge have attracted international attention.

As a result, the issue of traditional knowledge has been brought to the general debate surrounding intellectual property. These cases involve, what is often referred to as ‘biopiracy’.

The examples of turmeric and neem (Indian traditional herbal medicine) illustrates the issues that can arise when patent protection is granted to inventions relating to traditiona knowledge which is already in the public domain. In these cases, invalid patents were issued because the patent examiners were not aware or the relevant traditional knowledge.

e.g., India is one of the country possessing the richest diversity of rice (2000 varieties) Basmati rice is distinct for its unique aroma and flavour and 27 documented varieties of Basmati are grown in India. There is reference to Basmati in ancient texts, folklore and poetry, as it has been grown for centuries.

In 1997, an American company Rice teen. Got patent rights on Basmati rice through the US patent and Trademark Office. This allowed the company to sell a ’new’ variety of Basmati, in the US and abroad.

This ’new’ variety of Basmati had actually been derived from Indian farmer’s varieties. Indian Basmati was crossed with semi-dwarf varieties and claimed as an invention or a novelty. The patent extends to functional equivalents, implying that other people selling Basmati rice could be restricted by the patent.

If we are not vigilant and we do not immediately counter these patent applications, other countries/individuals may encash on our rich legacy and we may not be able to do anything about it.

However, India achieved success in contesting patent for Basmati, rice as on September 2000 Rice teen withdraw the claims contested by India. Therefore, ignoring our traditional knowledge, can be proved costly in the area of biological patenting.

Answer

Genetically Modified Plants (GMOs) are the plants, whose genes have been altered by manipulation.

Genetic modification of plants is useful in different areas. Because of following reasons

(a) It increases tolerance against abiotic stresses (cold, drought, salt, heat).

(b) It reduces reliance on chemical pesticides (pest-resistant crops).

(c) It reduces post-harvest losses.

(d) It increases the efficiency of minerals used by plants (this prevents early exhaustion of fertility of soil).

(e) It enhances nutritional value of food, e.g., vitamin-A enriched rice (golden rice).

(f) It creates tailor-made plants to supply alternative resources such as starch fuels and pharmaceuticals to industries.

Answer

Recombinant DNA vaccines are produced by using genetically engineered plasmids that have gene inserts possessing the surface proteins of a pathogen. After the binding of pathogens to these surface proteins, a weak immune response is elicited but it do not results in infection.

These plasmids are inserted in bacteria or yeast cells that expresses the viral proteins, which are then injected into the human host as vaccine, where they are recognised as foreign and an immune response is elicited.

Recombinant hepatitis-B vaccine and polio vaccine are the examples.

Answer

The line of treatment for a genetic disease is different from infectious diseases because genetic diseases cannot be treated with any medication, only the signs and symptoms can be taken care of. The only way to treat them is by the manipulation of genes to correct or replace the faulty genes.

On the other hand, infectious diseases are caused by pathogens and therefore, can be treated by substances that kill the pathogen or hamper its growth.

Thinking Process

A single stranded DNA or RNA tagged with a radioactive molecule is called probe.

Answer

Early detection of a disease is not possible by conventional diagnostic methods. So, some techniques have been implanted for early diagnosis like PCR, recombinant DNA technology and ELISA.

In recombinant DNA technology, a probe is used. It is allowed to hybridise to its complementary DNA in the clone of cells. The cells are then detected by autoradiography.

The cell with mutated gene will not be observed on the photographic film because, the probe will not have complementarity with the mutated gene.

Answer

Gene therapy is a collection of methods that allows the correction of gene defects diagnosed in a child or embryo. Correction of a genetic defect involves the delivery of a normal gene into the individual or embryo to take over the function of and compensate for the non-functional gene.

The first clinical gene therapy was given in 1990 to a 4 yrs old girl with Adenosine Deaminase (ADA) deficiency.

ADA deficiency is caused due to the deletion of gene for Adenosine Deaminase. It can be cured by bone marrow transplantation or by enzyme replacement therapy. In both the approaches, it is not completley curable.

It may recurrent in nature because in the process of gene therapy, lymphocytes used are found to be mortal in nature and the patient requires periodic infusion of such genetically engineered lymphocytes.

For permanent cure, gene isolated from the bone marrow cells producing ADA is introduced into the cells at early embryonic stages.

Answer

The fermentation process is the basis of many industries in order to produce diverse products. Fermentation means a process in which microorganisms that are cultured on a large scale, convert a substrate into a product which is useful to human.

The fermentation process is divided into two stages namely

Upstream and downstream processing both of these processes can be discussed taking an example of citric acid production.

The upstream processing in biotechnology involves identifying a material. This forms the initial process of fermentation. It deals with inoculum preparation, preparation of culture media, scale up of the entire process and inoculation.

When the products are subjected to a series of processes including separation and purification of the product, it is collectively known as downstream processing. It deals with the post-harvest product, i.e., recovery-clarification, purification, polishing and formulation till the packaging of the desired product.

Answer

An antigen is a foreign substance that elicits the immune response and results in the formation of an antibody.

Antibody is a protein that is synthesised by the body in response to an antigen.

Antigen and antibody shows high degree of specificity in binding to each other.

Two diagnostic kits based on antigen-antibody interaction are

(a) ELISA for HIV.

(b) Pregnancy test kits.

Thinking Process

ELISA is based on the principle of antigen - antibody interaction. Any infection coused by a pathogen can be detected by the presence of antigens (proteins, glycoproteins, etc.) or by detecting the antibodies synthesised against the pathogen.

Answer

Yes, one can use antibody against the enzyme (that is responsible for the metabolism of phenylanaline) to develop ELISA based diagnostic technique. The patient, in which the enzyme-protein complex is absent would give a negative result in ELISA when compared to the normal individual.

Answer

Mature functional insulin is obtained by the processing of pro-hormone which contains an extra peptide called C-peptide or connecting peptide.

It connects the $\mathrm{A}$ and $\mathrm{B}$ chains in proinsulin. This $\mathrm{C}$-peptide is removed during the maturation of pro-insulin to insulin and A and B chains gets linked by disulphide linkage.

Free C-peptide

Maturation of proinsulin to insulin

Answer

Gene therapy would be a better option because it has the potential to completely cure the patient. It is because the correct gene once introduced in the patient, can continue to produce the correct protein enzyme. Enzyme therapy does not offer permanent cure as it needs to be given to the patient on regular basis. It is also more expensive.

Answer

Transgenic animals are the animals in which a foreign genes are expressed. Such animals can be used to study the fundamental biological process/phenomenon, e.g., by using model organisms like mouse we can determine how genes are regulated (gene regulation), how they affect the normal functions of the body and its development, etc.

Transgenic animals are also used for producing products useful for mankind, e.g., Transgenic cow (rosie). Which produced human protein enriched milk $(2.4 \mathrm{~g} / \mathrm{L})$. The milk contained the human alpha-lactalbumin and was nutritionally a more balanced product for human babies than natural cow-milk.

Answer

Foreign gene is usually ligated to a plasmid vector and introduced in the host. As plasmid replicates, and makes multiple copies of itself, so does the foreign gene gets replicated and its several copies are made. When the host organism divides, its progeny also receives the plasmid. DNA containing the foreign gene

The whole process can be visualised in the figure given below

Answer

Bt cotton is made resistant to certain specific taxa of pests (lepidopteran, dipterans and coleopterans). It is quite likely that in future, some other pests may infest these Bt-cotton plants. It is similar to immunisation against smallpox which does not provide immunity against other pathogens like those, that causes cholera, typhoid etc.

Thinking Process

A patient suffering from ADA deficiency can be cured by using ‘gene therapy’. Gene therapy is a collection of methods that allows the correction of a gene defect that has been diagnosed in a child/embryo.

Answer

ADA enzyme is crucial for the immune system to function. Deletion of the gene for adenosine deaminase results into ADA deficiency.

In some children, ADA deficiency can be cured by bone-marrow transplantation, while in others it can be treated by enzyme replacement therapy, in which functional ADA is given to the patient by injection. But the problem with both of these approaches is that they are not completely curative.

It may recurrent in nature as in the process of gene therapy, lymphocytes used are found not to be immortal in nature and the patient requires a periodic infusion of such genetically engineered lymphocytes.

For permanent cure, gene isolated from the bone-marrow cells producing ADA is introduced into cells at early embryonic stages.

Answer

Animals that have had their DNA manipulated to possess and express an extra (foreign) gene are known as transgenic animals.

Following are the four main areas where they can be utilised

(i) To Study Normal Physiology and Development

These animals can be used to study that which factor/gene products are needed at what time of development. By the expression of certain genes, they help scientists to understand the normal gene expression at various stages of growth and development.

(ii) Study of Diseases

Transgenic animals can be created to serve as models for various human diseases. They also help us to understand the involvement of various genes in diseases like cancer, Parkinson’ disease etc.

(iii) Vaccine Safety

Transgenic animals can be used to test vaccines like polio vaccine. Transgenic mice have shown promising results in this area and would replace the vaccine testing on monkeys in the years to come.

(iv) Chemical Safety Testing

Transgenic animals are created which are more sensitive to certain chemicals/drugs. These are used to study the toxicity or side effects of that chemical/drug. The advantage is that we get results faster.

Answer

After identifying a useful gene in bacteria, following steps should be followed

(i) Isolation of useful gene using restriction endonucleases

$\downarrow$

(ii) Transferring the gene to a suitable vector to create a recombinant DNA molecule

$\downarrow$

(iii) Transfer of these recombinant DNA molecules to the target cells.

$\downarrow$

(iv) Screening of cells for transformation

$\downarrow$

(v) Selection of transformed cells

$\downarrow$

(vi) Regeneration of plants from the transformed cells to get transgenic plants.

Answer

Biotechnology has influenced our lives in the following ways

(i) It has provided us with genetically modified crops of better quality and high nutritive value.

(ii) It has made better and safer recombinant vaccines available to the human.

(iii) It has helped to develop transgenic animals that can produce human proteins.

(iv) It has enabled the cure of genetic diseases using gene therapy.

(v) Environment pollution has also been taken care of with the help of genetically engineered microbes.

Answer

Genetically modified plants have been useful in many ways as follows

(i) These plants are more tolerant to abiotic stresses (cold, drought, salt, heat).

(ii) They have reduced the reliance on chemical pesticides (pest-resistant crops).

(iii) They helped to reduce post harvest losses.

(iv) They increases the efficiency of mineral usage by plants (this prevents early exhaustion of fertility of soil).

(v) Enhanced nutritional value of food, e.g., vitamin-A enriched rice.

In addition to these uses, GM plants have been used to create tailor-made plants to supply alternative resources to industries, in the form of starches, fuels and pharmaceuticals.

Answer

(a) Genetically modified plants can reduce the usage of chemical pesticides by introducing pest resistant plants.

e.g., There are several nematodes that parasitie, a wide variety of plants and animals including human beings. A nematode Meloidogyne incognita infects the roots of tobacco plants and causes a great reduction in yield. A novel strategy was adopted to prevent this infestation which was based on the process of RNA interference (RNAi).

Using Agrobacterium vectors, nematode-specific genes were introduced into the host plant. The introduction of DNA was such that it produced both sense and antisense RNA in the host cells.

These two RNA’s being complementary to each other formed a double stranded RNA that initiated RNAi and thus, silenced the specific mRNA of the nematode. The consequence was that the parasite could not survive in a transgenic host expressing specific interfering RNA.

(b) Genetically modified plants can enhance nutritional value of food crops.

e.g., ‘Golden rice’ developed at Swiss Federal Institute of technology is an example of nutritionally modified crop. It is rich in vitamin-A ( $\beta$-carotene). The rice grains are golden-yellow in colour. It contains ‘beta-carotene’ gene from daffodil plant and also from some bacteria. Golden rice can prevent child blindness which is caused due to the deficiency of vitamin-A.

Answer

The disadvantages of insulin obtained from the pancreas of slaughtered cows and pigs are

(i) Insulin being a hormone is produced in very little amounts in the body. Hence, a large number of animals need to be sacrificed for obtaining small quantities of insulin. This makes the cost of insulin very high (Demand being many fold higher than supply).

(ii) Slaughtering of animals is not ethical.

(iii) There is a potential of immune response in humans against the administered insulin which is derived from animals.

(iv) There is possibility of slaughtered animals being infested with some infectious microorganism which may contaminate insulin.

Answer

The advantages of recombinant insulin are

(i) There is no need of animals to be sacrificed for the production of recombinant insulin.

(ii) Recombinant insulin was not found allergic to patients, while the insulin from an animal source caused some patients to develop allergy or other types of reactions to the foreign protein.

(iii) The cost of recombinant insulin is not very high. (Supply being many fold higher than demand).

Answer

Biopesticide is a pesticide which is

(i) Not chemical in nature.

(ii) More specific in action against the pest.

(iii) Safer for environment than chemical pesticides.

A popularly known bio-pesticide is $B t$ toxin, which is produced by a bacterium called Bacillus thuringiensis. Bt toxin gene has been cloned from this bacterium and expressed in plants. $B t$ toxin protein when ingested by the insect, gets converted to its active form due to the alkaline $\mathrm{pH}$ of the gut.

The activated toxin binds to the surface of midgut epithelial cells and create pores that causes swelling and lysis of the cell and eventually kills the insect.

Answer

The key tools for accomplishing the tasks of recombinant DNA technology with their functions are mentioned below

(i) Restriction endonucleases for cutting the desired DNA at desired places.

(ii)** Gel electrophoresis** for separating the desired DNA fragments.

(iii) Ligase enzyme for creating recombinant DNA molecule.

(iv) DNA delivery system like electroporation, microinjection, gene gun method, etc.

(v) Competant host (usually bacteria/yeast) to take up the recombinant DNA.