Cbse Class 12 Biology Revision Notes Chapter 12

Class 12 Biology Chapter 12 Notes: Biotechnology And Its Applications

 

The word Biology is derived from the Greek word ‘bio’, meaning life and ‘logos’, meaning study. Biology is defined as the science of life and consists of bacteria, animals, plants and fungi.

Biotechnology is a field of Biology that fundamentally deals with the large-scale production of biopharmaceuticals using genetically modified organisms. Biotechnology applications include diagnostics, genetically modified plants for agriculture, waste treatment, and energy production. 

Extramarks is one of the leading  platforms known and trusted for providing high-quality study materials for Class 11 to Class 12. Our team of academic subject experts have created study materials based on the latest CBSE syllabus and NCERT guidelines. Students can confidently rely on our comprehensive study solutions.

Extramarks Class 12 Biology Chapter 12 Notes covers topics of Genetically Modified Organisms developed from techniques such as  recombinant DNA technology. Also, students aspiring for careers in biotechnology or paramedical sciences can refer to Class 12 Biology Chapter 12 Notes to get an in-depth understanding of this subject.

 

Key Topics Covered in Class 12 Biology Chapter 12 Notes

 

Introduction:

Biotechnology deals with the industrial-scale production of biopharmaceuticals and genetically modified organisms. There are three critical research areas in biotechnology mentioned in Chapter 12 Biology Class 12 Notes.

  1. Provision of the best catalyst in the form of an enhanced organism, usually a pure enzyme or microbe.
  2. Creating optimal conditions through engineering for the action of a catalyst.
  3. Downstream processing technology to purify the organic compound

 

Applications of Biotechnology in Agriculture:

Few applications of biotechnology in the farming industry as covered in our Class 12 Biology Chapter 12 Notes are given below:

  • To enhance food production, we can look at three options; agrochemical based agriculture, organic agriculture and genetically engineered crop-based agriculture.
  • Despite the green revolution, increased yields are insufficient to feed the growing human population.
  • Moreover, better management practices and agrochemicals are often expensive to the farmers.
  • Hence the use of genetically modified crops was the only possible solution.
  • Genetically modified organisms are plants, animals, bacteria and fungi whose genes have been altered by manipulation.

 

Here are some benefits of genetic modification in plants:

 

  1. It has made crops more tolerant of abiotic stresses.
  2. It has reduced dependence on chemical pesticides.
  3. It has led to the reduction of post-harvest losses.
  4. It has helped to increase the efficiency of plants in using minerals.
  5. It has improved the nutritional quality of food such as vitamin A enriched rice.
  6. Genetically modified plants also help supply various resources to industries in the form of fuels and pharmaceuticals.

 

The benefits of genetically modified plants are covered in more detail in our Class 12 Biology Chapter 12 Notes. These notes are prepared by experienced faculty and have proven beneficial to lakhs of students who have already registered with Extramarks learning platform. Students can bank on these solutions not only for last-minute revision tests and exams, but also for clearing NEET, and other medical exams.

 

The use of Bacillus thuringiensis:

The bacteria Bacillus thuringiensis produces Bt toxin.  This  gene has been cloned from bacteria where it is expressed in plants to provide resistance to pests and insects. Due to the creation of biopesticides, the need for insecticides is prevented. Examples are Bt cotton, Bt tomato, soybean, potato, etc.

 

Bt Cotton:

 

  • Few strains of Bacillus thuringiensis produce proteins that kill certain insects such as tobacco budworm, beetles, mosquitoes and flies.
  • The inactive proteins, once ingested by the insect, are activated.
  • Due to the alkaline pH in the insect’s gut, the activated toxin binds to the epithelial cells and creates pores.
  • This causes cell swelling and lysis that kills the insect.
  • The selection of genes depends upon the crop and targeted pest. 
  • The toxin is coded by a gene named cry; for example, cryIAc and cryIIAb control Cotton bollworms and cryIAb control corn borers.

 

 

 

Pest Resistant plants:

 

  • Meloidogyne incognita, a nematode parasite, infects the roots of tobacco plants and decreases their yield.
  • A strategy called RNA interference was adopted to prevent this infestation.
  • RNAi is a method that involves the silencing of a specific mRNA. 
  • dsRNA molecule binds and prevents the translation of mRNA.
  • Agrobacterium vectors introduced DNA that produces both sense and antisense RNA in host cells.
  • The two RNAs being complementary to each other formed a double standard DNA that began the RNA interference and silenced the specific mRNA of the nematode.
  • The parasite could not survive in a transgenic host expressing interfering RNA. Hence the plant was protected from the parasite.

 

Biotechnological Applications In Medicine:

Recombinant DNA technology enables the mass production of effective therapeutic drugs. Recombinant therapeutics prevent unwanted immunological responses. Today, there are about 30 recombinant therapeutics globally, while 12 of these are being marketed in India. The fast pace advancement happening in medicine due to various Biotechnology applications will change the overall pharmaceutical industry. All students pursuing science, medical, biotech and similar streams are recommended to pay special attention to this development. They can refer to Extramarks Class 12 Biology Chapter 12 Notes where our experts have covered this topic at length. 

 

Genetically Engineered Insulin:

 

  • Earlier insulin used in the management of adult-onset diabetes was extracted from the pancreas of slaughtered cattle and pigs. However, this caused a few patients to develop allergies and other reactions.
  • Insulin consists of two short polypeptide chains: chains A and B, linked by disulphide bridges.
  • In mammals, insulin is synthesised by a prohormone which contains an extra stretch called the C peptide.
  • C peptide is absent in mature insulin and separated during maturation into insulin.
  • In 1983, Eli Lilly, an American scientist, formed two DNA sequences corresponding to human insulin’s A and b chains. This was introduced in the plasmids of E.coli to produce insulin chains.
  • The chains A and B were then extracted and combined to form human insulin.

 

Gene therapy:

 

  • Gene therapy is a corrective therapy applied to people with a hereditary disease where there is a correction of a gene defect that has been diagnosed in a child.
  • The correction involves the delivery of a normal gene into the individual to compensate for the non-functional gene.
  • Adenosine deaminase(ADA) deficiency was the first clinical gene therapy for a four-year-old girl in 1990. This enzyme is vital for the function of the immune system.
  • In some cases, ADA deficiency can be cured by bone marrow transplantation. While in others, enzyme replacement therapy is performed on the patient by injecting the functional area.
  • The first step toward gene therapy involves the extraction of Lymphocytes from the patient’s blood and growing in a culture outside the body.
  • A functional ADA cDNA is introduced into these lymphocytes and returned to the patient. Regardless, the cells require a periodic infusion of genetically engineered lymphocytes.
  • In an embryo, when the ADA was introduced to isolated genes from the bone marrow cells, it could be a permanent cure.

 

Apart from Class 12 Biology Chapter 12 Notes, students can also visit the Extramarks website for more study resources such as NCERT Solutions, CBSE Sample Papers, CBSE Revision Notes, etc. to step up their preparation.

 

Molecular Diagnosis:

  • For effective treatment, early diagnosis is crucial. Techniques like recombinant DNA technology, Polymerase Chain Reaction(PCR) and Enzyme-Linked Immuno-Sorbent Assay(ELISA) are used for early diagnosis. In any disease, the presence of a pathogen is usually suspected when a disease produces symptoms. One can only detect the symptom when the concentration of the pathogen is very high.

 

  • PCR is a method used:
  1. To detect a low concentration of a bacteria or virus by amplifying the nucleic acid.
  2. To detect HIV in patients.
  3. To check mutations in genes of Cancer patients.
  4. To identify genetic disorders.

 

  • A single-stranded DNA or RNA is tagged with a radioactive molecule which is then allowed to hybridise with its complementary DNA. The clone cells are detected with the help of autoradiography, where the clone with the mutated gene will not appear on the photographic film. The foundation for the technique of ELISA is antigen-antibody interaction.

 

Transgenic Animals:

 

Transgenic animals are animals whose DNA is altered by manipulation to express a foreign gene. Class 12 Biology Chapter 12 Notes highlight some common reasons for introducing transgenic animals.

 

  • Normal physiology and development:

Transgenic animals are specifically designed to study the regulation of genes and how it affects normal function. For instance, the study of insulin-like growth factors. The introduction of genes from other species alters the formation of this factor. The insulin-like growth factor helps study the biological role of the factor   in  the body.

 

  • Study of Disease:

Transgenic animals help us understand the contribution of genes to the development of diseases. These are made to serve as models for human diseases to investigate new treatments as seen in cancer, cystic fibrosis, rheumatoid arthritis and Alzheimer’s. .

 

  • Biological products:

Transgenic animals are used to create biological products by introducing a portion of Genes coding for a particular product. For instance, human proteins treat diseases such as emphysema, phenylketonuria and cystic fibrosis. The first transgenic cow, named Rosy, was introduced in 1997. The cow produced protein-enriched milk that contained Alpha-lactalbumin and served as a more balanced product for human babies.

 

  • Safety of vaccines:

Before humans use vaccines, they are tested on transgenic mice for safety. They are being used to test the safety of the polio vaccine. 

 

  • Chemical safety testing:

Chemical safety testing is also termed toxicity testing or safety testing. Transgenic animals carry genes that are more sensitive to toxins than non-transgenic animals.  Toxicity tests in  animals are used to obtain results in less time.

 

Ethical Issues:

  • Ethical standards are required to evaluate all human activities.
  • GEAC(Genetic Engineering Approval Committee), introduced by the Indian government, makes decisions regarding the validity of GM research and the safety of the introduction of GM organisms for public services.
  • There are 2 lakh varieties of rice in India. Twenty-seven types of basmati are grown in the country.
  • In 1997, patent rights were granted to an American company on basmati rice.
  • This permitted the company to sell a new variety of basmati in the US and abroad. Indian farmers’ varieties developed a new variety. However, the Indian basmati was crossed with semi-dwarf varieties and was claimed as an invention.
  • If these patent applications are not counted immediately, other countries will encash on our legacy.

 

What is biopiracy?

 

As explained in our Class 12 Biology Chapter 12 Notes, the use of bioresources by multinational companies and other organisations without authorisation from countries and compensatory payment from the people concerned is termed biopiracy. 

Most industrial Nations tend to exploit traditional knowledge to develop modern applications and the same time, effort and expenditure for commercial purposes. Some nations are now developing loss to prevent unauthorised exploitation of bioresources and traditional knowledge. The parliament of India has recently cleared the second amendment of the Indian patent bill. It takes into consideration the patent terms, emergency provision and development initiative.

Students get detailed and authentic study material   in our Class 12 Biology Chapter 12 Notes. These study notes are prepared by subject matter experts at Extramarks,  after  thorough research and analysis to help students achieve their study goals without much hassle and even get to clarify their doubts to master the topic. . 

 

Class 12 Biology Chapter 12 Exercise Questions and Answer Solutions

 

Extramarks is one of the leading websites for board exam preparation. Our subject experts have included a lot of exercise questions and answers in our Class 12 Biology Chapter 12 Notes. To get good grades in Biology, one needs to get the hang of the chapter and even practise answer writing skills to stay ahead in the competition.  The answers should briefly cover all essential points. This regular habit of solving questions will definitely enhance the confidence in achieving high marks in the final exams.

 

Students can click on the links provided below to access the solutions for various Exercises they will need to prepare for the examination.

 

  • Chapter 12: Exercise 12.1 – Question and Answers 

 

Extramarks website provides excellent solutions for every exercise question. The solutions include a detailed explanation of topics covered in biotechnology and its applications, pointwise in a systematic and organised manner. You can click on the respective links to view Class 12 Biology Exercise and Answer Solutions.

 

Apart from Biology Chapter 12 Class 12 Notes, Students can visit the Extramarks website for more information by clicking on the links given below:

 

NCERT Exemplar for Class 12 Biology Chapter 12 Notes

NCERT Exemplar books are available along with the NCERT Textbooks. The role of Exemplar is to be the extended Q&A study guide along with the textbook. The Exemplar book is a collection of a variety of questions for students to practice and to develop a strong conceptual clarity.    . . Students will get to practise a variety of questions covered in Exemplars – MCQs, short answer questions, long format questions, etc. 

While solving the questions from Exemplar, students will also get to revise key topics. . They will  get to know their grey areas and begin to work on them at an early stage to avoid any last minute hassle. Students can  clarify  their doubts and be more confident ahead of the exams.

Students can first study the chapter from the NCERT textbook and then refer to our Class 12 Biology Chapter 12 Notes. Then they can solve questions given in NCERT Exemplar. This way students will have a comprehensive understanding of the Biotechnology chapter. Our study notes also contain solutions for all the questions covered in NCERT Textbook and NCERT Exemplar books.

 

Key Features of Class 12 Biology Chapter 12 Notes

Let’s look at some essential features of Class 12 Biology Chapter 12 Notes:

  • Extramarks is one of the leading websites that provides students with authentic and reliable study materials.
  • The Notes are prepared based on the latest CBSE syllabus and follows the NCERT guidelines.
  • These are prepared by Extramarks professionals in the field of Biology and Biotechnology.
  • Class 12 Biology Chapter 12 Notes are designed for students to understand the information in a more simple language with the use of visual diagrams and real-life applications.
  • All lengthy concepts and complicated definitions are prepared in a pointwise manner for the students.
  • Extramarks website provides a platform for students to revise and prepare for their board examination and NEET through their comprehensive Notes and solutions.

Q.1 Give three advantages of using genetically engineered human insulin?

Ans

Advantages of using genetically engineered human insulin are:

1. It causes very less or no allergic reactions.

2. It is produced in larger quantity.

3. Strict vegetarians can use it because no animals are involved in its production.

Q.2 Why is Bt-toxin considered more ecofriendly than the conventional chemical pesticides?

Ans

Unlike chemical insecticides which are generalised and nonspecific in their effects, Bt-toxin is very selective in nature and kills only the target pest species. Non-target species remain unharmed, thus the environmental balance is maintained.

Q.3 In Gujarat some strains of pink bollworm have shown resistance against Bt-cotton. What is the reason behind this resistance development?

Ans

The resistance was developed due to mutation in a gene encoding a Cadherin receptor which binds “Cry” protein.

Q.4 What is ‘Dicer’?

Ans

Dicer is an endoribonuclease that cleaves double-stranded RNA (dsRNA) into short double-stranded RNA fragments called small interfering RNA (siRNA) which are 20-25 nucleotides long.

Q.5 What is ‘Transposon’?

Ans

Transposons are sequences of DNA that can move around to different positions within the genome of a single cell, by the process called transposition. Transposons were also once called jumping genes.

Q.6 Why RNAi is considered as an important technique of Biotechnology?

Ans

RNAi is considered as an important technique of Biotechnology because:

1. This technique can be used to trace the function of a gene.

2. It can be used to discover new drugs which can suppress or enhance the expression of a gene or set of genes.

Q.7 During the process of downstream processing, how are the two chains (A and B) linked together to form activated enzyme.

Ans

Downstream processing of biosynthetic insulin includes the extraction and combination of its two separate chains through disulphide linkage. Disulphide bonds are generated through thiol-disulphide exchange reactions between the “cystein” moieties of the two peptides.

Q.8 Write a short note on genetically engineered insulin and its production by Eli Lilly.

Ans

– Insulin is an important life saving drug for diabetic patients.
– Insulin consists of two short polypeptide chains: chain A and chain B, that are linked together by disulphide bridges.
– In mammals, including humans, insulin is synthesised as a prohormone which contains an extra stretch called the C peptide.
– This C peptide is not present in the mature insulin and is removed during its maturation.

– The main challenge for production of insulin using rDNA techniques was getting insulin assembled into a mature form.

– In 1983, Eli Lilly, an American company prepared two DNA sequences corresponding to A and B, chains of human insulin and introduced them in plasmids of E. coli to produce insulin chains.

– Chains A and B were produced separately, extracted and combined by creating disulfide bonds to form human insulin.

Q.9 Why does insecticidal “Cry proteins” not affect mammals?

Ans

Cry proteins are absorbed into epithelial cells of insect midgut through Cadherin receptors expressed on their surface. Mammals do not have such receptors hence they are not affected by “Cry proteins”.

Q.10 What are the critical research areas in biotechnology?

Ans

Three critical research areas of biotechnology are:
(i) Providing the best catalyst in the form of improved organism usually a microbe or pure enzyme.
(ii) Creating optimal conditions through engineering for a catalyst to act.
(iii) Downstream processing technologies to purify the protein/organic compound.

Q.11 What are the key applications of biotechnology?

Ans

The key applications of biotechnology include therapeutics, diagnostics, genetically modified crops for agriculture, processed food, bioremediation, waste treatment, and energy production.

Q.12 How can biotechnology benefit agriculture?

Ans

Biotechnology increases the food production by

(i) organic agriculture; and

(ii) genetically engineered crop-based agriculture.

Q.13 Expand and explain GMO.

Ans

Plants, bacteria, fungi and animals whose genes have been altered deliberately for human welfare and development are called Genetically Modified Organisms (GMO).

Q.14 How are genetic modifications beneficial in plants?

Ans

Genetic modifications in plants are beneficial in many ways:
(i) make crops more tolerant to biotic stresses (cold, drought, salt, heat).
(ii) reduced reliance on chemical pesticides (pest-resistant crops).
(iii) help to reduce post harvest losses.
(iv) increase 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.

Q.15 What is Bt toxin?

Ans

Bt toxin is produced by a bacterium called Bacillus thuringiensis. Bt toxin gene has been cloned from the bacteria and has been incorporated in crop plants to provide resistance to their parasitic insects without the need of insecticides.

Q.16 Write a short note on Bt Cotton.

Ans

Bt Cotton is considered as a genetically modified strains of cotton plant which produces proteins that kill certain insects such as lepidopterans (tobacco budworm, armyworm), coleopterans (beetles) and dipterans (flies, mosquitoes).

Q.17 Explain the mode of action of the Bt toxin. Why does it not kill the Bacillus?

Ans

B. thuringiensis forms protein crystals during the spore forming phase of their growth. This crystal contains toxic insecticidal protein.These protein molecules exist as inactive protoxins but when an insect ingest the inactive toxin, it is converted into an active form of toxin due to the alkaline pH of the insect gut through solubilisation of the crystals. The activated toxin binds to the surface of midgut epithelial cells and create pores that cause cell swelling and lysis, eventually causing insect death.

Q.18 What does the gene named ‘cry’ code for?

Ans

The gene ‘cry’ code for the crystalline proteinaceous toxin called Bt-toxin in Bacillus thuringiensis.

Q.19 What does RNAi stands for? Explain RNAi technology using an example.

Ans

RNAi stands for RNA interference.
RNAi takes place in all eukaryotic organisms as a method of cellular defense. This method involves silencing of a specific mRNA due to a complementary dsRNA molecule that binds to and prevents translation of the mRNA (silencing). The source of this complementary RNA could be from an infection by viruses having RNA genomes or mobile genetic elements (transposons) that replicate via an RNA intermediate.
Example : Using Agrobacterium vectors, nematode-specific genes were introduced into the host plant. The introduction of DNA was such that it produced both senseand anti-sense RNA in the host cells. These two RNA’s being complementary toeach other formed a double stranded (dsRNA) that initiated RNAi and thus, silenced the specific mRNAof the nematode. The consequence was that the parasitecould not survive in a transgenic host expressing specific interfering RNA. Thetransgenic plant, therefore, got itself protected from the parasite.

Q.20 What are the various applications of biotechnology in medicine?

Ans

Biotechnology has widespread applications in the field of medicine:
Many pharmaceutical products have been produced by using recombinant DNA technology. Monoclonal antibodies, vaccines, antibiotics, genetically engineered insulin, steroids are produced with the help of biotechnology.

Q.21 A person is born with a genetic disease. Can he be cured? Explain how?

Ans

Person can be cured with the help of Gene Therapy.
– In Gene therapy, genes are inserted into a person’s cells and tissues to treat a disease.
– Correction of a genetic defect involves delivery of a normal gene into the individual or embryo to take over the function of and compensate for the non- functional gene.

Q.22 What is Gene Therapy?

Ans

Gene therapy is a collection of methods which allows correction of a genetic defect through various techniques of recombinant DNA technology.

Q.23 Expand ADA. What are the therapies available for it? What role can gene therapy play in curing ADA?

Ans

– ADA stands for Adenosine deaminase deficiency.
– The therapies available for curing ADA is Gene therapy, Enzyme replacement therapy and Bone marrow transplantation.

Role of gene therapy in curing ADA:

– The first clinical gene therapy was given in 1990 to a 4-year old girl with Adenosine deaminase (ADA) deficiency.
– The lymphocytes from the blood of the patient are grown in a culture outside the body.
– A functional ADA cDNA (using a retroviral vector) is then introduced into these lymphocytes, which are subsequently returned to the patient.

– As these cells are not immortal, the patient requires periodic infusion of such genetically engineered lymphocytes.

– If the gene isolate from marrow cells producing ADA is introduced into cells at early embryonic stages, it could be a permanent cure.

Q.24 How does biotechnology serve the purpose of early detection of diseases?

Ans

Recombinant DNA technology, Polymerase Chain Reaction (PCR) and Enzyme Linked Immuno-Sorbent Assay (ELISA) are some of the techniques of biotechnology that serve the purpose of early disease detection.

Q.25 Expand and describe ELISA.

Ans

-ELISA stands for Enzyme-Linked Immuno Sorbent Assay.
– ELISA, is a biochemical technique used mainly in immunology to detect the presence of an antibody or an antigen in a sample. The ELISA has been used as a diagnostic tool in medicine and plant pathology, as well as a quality control check in various industries.

Q.26 How does PCR help in diagnosis of diseases?

Ans

– PCR stands for Polymerase Chain Reaction. It is used for amplification of DNA.
– It is a powerful techqnique to identify many genetic disorders like gene mutation in cancer etc.
– A very low concentration of a bacteria or virus ( before the development of symptoms ) can be detected by amplification of their nucleic acid by PCR.

Q.27 What are transgenic animals? What are their applications?

Ans

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

Applications of transgenic animals:

  • Transgenic animals can be specifically designed to allow the study of genes regulation, and their affect on the normal functions of the body and its development, e.g., study of complex factors involved in growth such as insulin-like growth factor.
  • Many transgenic animals are designed to show genes contribution in the development of disease.
  • Transgenic animals also produce useful biological products that can be created by the introduction of the portion of DNA (or genes) which codes for a particular product such as human protein (α-1-antitrypsin) used to treat emphysema.
  • Transgenic mice are being developed for use in testing the safety of vaccines before they are used on humans.
  • Transgenic animals are made that carry genes which make them more sensitive to toxic substances than non-transgenic animals which help in testing the toxicity of drugs in shorter period of time.

Q.28 Expand GEAC. What does it do?

Ans

– GEAC stands for Genetic Engineering Approval Committee.
– It is an Indian government organization which will make decisions regarding the validity of GM research and the safety of introducing GM-organisms for public services.

Q.29 Write a short note on the conflict over patent of Basmati rice.

Ans

In 1997, an American company 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 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.

Q.30 What is Biopiracy?

Ans

The use of bio-resources by multinational companies and other organisations with no proper authorisation from the countries and people concerned without compensatory payment, is termed as Biopiracy.

Q.31 Which living system is popularly used for the production of recombinant or modified proteins?

Ans

Bacterial cells are popularly used for the expression of recombinant or modified proteins.

Q.32 Why are bacterial based systems used for producing genetically engineered insulin?

Ans

Bacterial based systems are used for producing genetically engineered insulin because:

1. They have small Generation time.

2. Recombinant protein (i.e., insulin) can be easily extracted.

3. Human body shows very less or no resistance against recombinant proteins produced in bacterial systems.

Q.33 Write a short note on patent issues related to Basmati rice.

Ans

Basmati rice, sought-after for its fragrant taste, was developed by Indian farmers over hundreds of years, but the Texan company RiceTec obtained a patent on September 2, 1997 for a cross-breed with American long-grain rice. This patent was granted by US Patent and Trademarks Office (USPTO). June 2000, Indian government has filed 50,000 pages of scientific evidence to the US Patents and Trademarks Office, insisting that most high quality basmati varieties already possess these characteristics. Claims filed by Ricetec numbered 1 to 3; 5 to 7; 10, 12 to 14 and 18 to 20 of the Basmati Patent have been rejected by the USPTO.

Q.34 Observe the flow chart of a clinical therapy given to a four year old patient for an enzyme.

Try to answer the following questions:

  1. Which clinical therapy is being outlined in the given flowchart?
  2. Identify the disease which can be cured by this treatment.
  3. Does the given treatment completely cure the disease?

Ans

  1. Gene therapy is being outlined in the given flowchart.
  2. Adenosine deaminase (ADA) deficiency disease can be cured by the given therapeutic treatment.
  3. No, the given treatment does not cure the disease completely as genetically engineered lymphocytes are not eternal. So, the patient requires periodic infusion of cells.

The disease can be cured permanently cured if the gene isolated from bone marrow cells producing ADA is introduced into cells at early embryonic stages.

Q.35 Bt crops are genetically modified crops, which are produced by the insertion of bacterial genes into plant cell.

  1. Is it possible to insert bacterial gene into a plant DNA?
  2. Suggest an appropriate answer how is it possible?

Ans

  1. Yes, it is possible to insert bacterial gene into a plant cell by a technique known as genetic engineering.
  2. Genetic engineering makes it possible to transfer cry gene of Bacillus thuringiensis into plant DNA by Agrobacterium mediated transformation. The steps involved are:
  1. Isolation of bacterial DNA
  2. Generation of rDNA by incorporating the target DNA from bacteria
  3. Transfer of rDNA into the host cell
  4. Selection of transformed host cell to produce a large amount of insert

Q.36 A technique ‘X’ has been used in producing transgenic plants resistant to nematodes.

In this technique, nematode specific genes are introduced into the host plant in such a manner that it produces both sense and antisense RNA.

Based on the given information, answer the following questions:

  1. Name the vector used in the above mentioned technique.
  2. How is RNAi initiated?
  3. How does RNAi strategy work?

Ans

  1. Agrobacterium is a vector through which nematode specific genes are introduced into a host plant.
  2. Sense and antisense RNA, being complementary to each other, form double stranded RNA (dsRNA) that initiates RNAi and thus; silences a specific mRNA of a nematode.
  3. RNAi prevents translation of a specific mRNA (silencing) due to a complementary dsRNA molecule.

Q.37 Read the statements from ‘A’ to ‘F’ and fill the correct word to complete them.

  1. The technique by which genetic material of an organism is manipulated for yielding useful products is ______.
  2. Production of insulin includes a technique in which human DNA is inserted into ____ which then grows and produces a synthetic version of human insulin.
  3. The technology which uses biological processes to produced desired product for human welfare is known as ______.
  4. The ____ genes code for Bt cotton.
  5. The _____ is a technique in which multiple copies of nucleotide sequence are synthesised under in-vitro conditions using complementary primers and DNA polymerase enzyme.

Ans

  1. Genetic engineering
  2. E.coli
  3. Biotechnology
  4. Cry
  5. Polymerase chain reaction (PCR)

Q.38 Read the statement given below and answer the following questions:

‘X’ is used to cut DNA at specific loci.

  1. What is ‘X’ in the given statement?
  2. How can we use ‘X’ to detect differences in DNA of different people?

Ans

  1. ‘X’ is a restriction enzyme in the given statement. Restriction enzymes are used to cut DNA at specific loci.
  2. We can use restriction enzymes to detect differences in DNA of different people as given below:
  1. Restriction enzymes are sensitive to changes in DNA sequences.
  2. They recognise only a particular site.
  3. Change of a single base at a restriction site can cause it to be “lost”, i.e., no longer recognised by the enzyme.
  4. It results in varying lengths of DNA fragments in different people having differences in DNA.

Q.39 The given below steps (a to e) are involved in a technique that helps to produce genetically modified products. Fill up the blanks with appropriate and correct answer.

Ans

a) Plasmid

b) Desired gene of interest from source organism

c) Plasmid + gene of interest (modified plasmid)

d) Insertion of modified plasmid into bacterial cell for multiplication and division

e) Bacterial cell

Q.40 The following is a Southern blot of EcoRI-digested DNA of wheat plants from two different inbred lineages, K and Z.

Autoradiogram (I) shows the bands that was developed after probing the blot with 32P-labelled cDNA 1, while autoradiogram (II) shows the same blot after it was exposed to probe and re-probed with 32P-labelled cDNA 2.

  1. Which bands are expected to be visible in the autoradiogram of a similarly probed Southern blot prepared by using EcoRI-digested DNA from F1 hybrid plants yielded by crossing the two inbred lineages?
  2. What can be inferred about the genes depicted by band b1 on blot I of two inbred lineages, K and Z?
  3. Suppose F1 progeny were crossed with plants possessing bands b1, b4, and m3. DDNA was isolated from several individual progenies and digested with EcoRI. Then, the resulting DNA fragments were separated by gel electrophoresis, transferred to a nylon membrane and hybridised with radioactive cDNA 1 and cDNA 2 probes.

The following table summarises the bands present in autoradiograms obtained by using DNA from individual progeny:

Does this data provide evidence for RFLPs?

Ans

  1. b1, b2, b3, b4, m1, m2 and m3 bands are expected to be visible in the autoradiogram of a similarly probed Southern blot prepared by using EcoRI-digested DNA from F1 hybrid plants yielded by crossing the two inbred lineages
  2. Band b1 represents a locus whose DNA is homologous to cDNA 1. Since the marker is not polymorphic in the parents, it cannot be mapped in this cross.
  3. cDNA 1 probe detects one RFLP locus with alleles that are visualised as band b4 and b2/b3. cDNA 2 detects another RFLP locus with alleles that are visualised as band m3 and m1/m2. The two loci are linked with a recombination frequency of 20%.

Q.41 If you have to clone an unidentified human gene, which procedure of biotechnology can help you to place this gene on the cytological map of human genome without carrying out pedigree analysis? Also, design the steps that can be followed for this purpose.

Ans

If a clone of gene is available, fluorescent in situ hybridisation (FISH) can be opted to determine the human chromosome that carries the gene and localise the gene on the chromosome.

Steps involved in this method are:

  1. Couple the single-stranded copies of the clone to a fluorescent probe.
  2. Hybridise it to a denatured DNA in chromosomes.
  3. Remove the free probe by washing.
  4. Locate the fluorescent probe by using a fluorescence microscope

Q.42 As per the recent discovery, CF gene and its product can help in the treatment of cystic fibrosis by the method of somatic-cell gene therapy.

Being a biology student, try to enlist the possible obstacles that scientists may face while carrying out somatic-cell gene therapy to treat this genetic disorder?

Ans

The possible obstacles that scientists may face while carrying out somatic-cell gene therapy to treat this genetic disorder are:

  1. Size of CF gene: Size of CF gene is approximately 250 kb, which can be a matter of concern as it is extremely large to fit in the standard gene transfer vectors.
  2. Insertion of transgene into enough cells: Another major obstacle can be insertion of transgene into enough of the target cells of the patient in order to reduce the symptoms.
  3. Development of expression vector: One more challenge can be the development of an expression vector containing the gene that can result in long-term expression of the introduced gene into the transgenic cells.

Q.43 Currently, a strategy of anti-sense RNA has been used to block the expression of certain genes in both prokaryotic and eukaryotic organisms.

  1. Is this strategy applicable for complete blockage of expression of a gene? Elaborate.
  2. Apply this strategy on vine ripened tomatoes and explicate how can it be helpful to increase their shelf life?
  3. Can this strategy prevent fatal genetic disorders? Apply your knowledge of this strategy to justify your answer.

Ans

  1. Yes, this strategy is applicable for complete blockage of expression of a gene. It can be achieved:
  1. either by reintroducing multiple copies of ‘anti-sense gene’ into host cells or,
  2. by using a very strong promoter to allow the transcription of the inverted coding sequence.
  1. Strategy of ‘anti-sense RNA’ reduces the expression of polygalacturonase gene in tomatoes by 10% of its normal level due to which, the firmness of vine ripened tomatoes enhances and shelf life increases.
  2. Yes, this strategy can prevent fatal genetic disorders.

When the genetic sequence of a particular gene is known to be a cause of a particular disease, it is possible to synthesise a strand of nucleic acid that can bind to the mRNA produced by that gene and inactivate it. This is because mRNA has to be single stranded in order to carry out translation.

Q.44 Scientists have used specially designed DNA chips to find the SNPs in 73 protein coding genes in 70 organisms.

They scanned approximately 185 kb of genomic sequence comprising comprising 82 kb of coding, 31 kb of non-coding and 72 kb of untranslated sequences. They identified 858 possible SNPs, out of which 350 were within the coding sequences; which are demarcated as cSNPs.

Out of the total cSNPs, 200 would change the sequence of amino acid in one of the proteins.

Analyse the data and answer the following questions:

  1. Calculate the frequency of SNPs in the sample.
  2. Is there equal distribution of SNPs in coding and non-coding sequences? Carry out the required calculations to support your answer.
  3. In humans, approximately 40,000 ESTs (expressed Sequence Tags) have been identified and the estimated number has to reach 75,000. Based on the given statistical data, predict the number of SNPs in:
  1. human genes,
  2. non-coding regions and
  3. coding regions that do not affect the structure of proteins.

Ans

  1. In 185,000 bp, there are 858 possible SNPs.

So, average number DNA sequence per SNP = 185,000/858 ≈215 bp of DNA sequence between two SNPs

  1. In coding sequences, percentage of SNPs= (350/ 858) X 100 ≈ 41%

In non-coding sequences, percentage of SNPs= [(858 -350)/ 858] X 100 ≈ 59%

From the calculations, it can be observed that smaller percentage of SNPs lie in the coding sequences, which signifies that there is lesser variation in these sequences.

  1. If there are 75,000 genes, we can expect about 8.58 X 105 SNPs in a human genome.

So, (858 SNPs/ 73 genes) X 75,0000 genes ≈ 881506. 84

  1. No. of SNPs in non-coding regions = [(858 -350)/ 858] X 100 ≈ 59%
  2. No. of SNPs in coding regions = (350/ 858) X 100 ≈ 41%.

Approx. [(350-200)/ 858] X 100 ≈ 17% would not affect the structure of protein because they do not change the sequence of amino acid in a protein.

Q.45 Read the case study on patent of an anti-cancer drug carefully.

A British pharmaceutical manufacturer is leading the production of an anti-cancer drug, which is exported to major developed countries for the last 20 years, and recently to developing countries, particularly in Southeast Asia.

The active ingredient of the drug was patented by him, however the original patent expired 3 years ago.

A new improved process for making the drug was patented 10 years ago, and this patent is still effective in various countries like Singapore, Malaysia and Indonesia.

Two years ago, the manufacturer observed that a generic manufacturer based in Vietnam was making and exporting the anti-cancer drug to Malaysia, which are being sold for half the price of his own drug. This posed a serious adverse effect on the sales.

  1. Apply your knowledge of intellectual property rights and advice the British manufacturer so that he can take possible actions against a generic manufacturer based in Vietnam.
  2. What could be the learning outcome for the British manufacturer from this experience?

Ans

  1. The possible advices are as follows:
  1. We can inform the British manufacturer that patents are the national rights, and therefore possible action can be taken only in the countries where the patent existed. In the given case, the manufacturer had not registered any patent in Southeast Asia.
  2. We can tell him that a patent for a product and process is infringed if a third party makes, imports, sells, offers to sell, stores or uses the product without the permission of the patent owner.
  3. We can advise him to contact a local expert to determine the exact process being used by the generic manufacturer before engaging in litigation.
  1. The learning outcome for the British manufacturer from this experience are:
  1. Now, he will submit his patent applications in potential future markets in Southeast Asia.
  2. He would have realised that the cost of litigation can be high and may be even more than the cost of lost business, so making a settlement is comparatively more cost-effective.

Q.46 A linear double stranded DNA has three restriction sites, which can either be BamHI or HaeIII site.

The DNA strand is digested completely with the help of both the ezymes. The products are purified and allowed to undergo an end-filling reaction using the Klenow fragment and [Ɑ-32P]-dCTP.

Then, the product of end filling reaction are purified and seperated by electrophoresis, stained with EtBr and subjected to autoradiography.

In the sample lane, the number below each band represent their main signal intensity in arbitary units.

Based on the information given, design an appropriate restriction map of the DNA, which is 8 kbp long?

Ans

Q.47 Identify the correct statements in each of the following:

  1. In the development of insect-resistant plant,
  1. It is easy to grow and maintain multiple copy integration events rather than maintaining single copy events of insect resistant plants.
  2. The level of expression of transgene does not influence the efficiency of the transgenic plant developed.
  3. A transgenic plant developed using multiple genes may be more effective in developing and maintaining resistance.
  4. The targeted insects cannot develop resistance against transgenic plants using a single gene.
  1. In naturally occurring Agrobacterium strains,
  1. all the virulent genes are constitutively expressed.
  2. Agrobacterium-induced galls do not require bacterial perseverance for their growth.
  3. The T-DNA region of Agrobacterium does not contain functional genes.
  4. Agrobacterium-induced galls require the application of plant hormones for their growth.
  1. In a binary plasmid vector, containing the expression cassette of a selectable marker gene, orientation of a cloned passenger gene cassette can be checked by PCR by using
  1. selectable marker gene-specific primers.
  2. vector-specific primers.
  3. passenger gene-specific primers.
  4. combination of passenger gene-specific and vector-specific primers.

Ans

  1. (iii) A transgenic plant developed using multiple genes may be more effective in developing and maintaining resistance.
  2. (ii) Agrobacterium-induced galls do not require bacterial perseverance for their growth.
  3. (iv) a combination of passenger gene-specific and vector-specific primers

Q.48 RNA transcripts are synthesised in the nucleus of eukaryotes and are then transported to the cytoplasm. Being a student of biotechnology, frame an experiment to demonstrate the same.

Ans

We can perform a simple pulse-and pulse/chase-labeling experiment which can demonstrate that RNA is synthesised in the nucleus and is then transported to the cytoplasm.

This experiment involves:

  1. pulse labelling eukaryotic culture cells by growing them in 3H-uridine for a few minutes and localising the incorporated radioactivity by autoradiography,
  2. repeating the experiment by adding huge amount of non-radioactive uridine to the medium in which the cells are growing after the labelling period and allowing the cells to grow in the non-radioactive medium for about an hour and,
  3. localising the incorporated radioactivity by the method of autoradiography.

Q.49 A scientist isolated an entire RNA from the nuclei of human cells growing in culture. He mixed this RNA with a purified denatured DNA fragment, that possessed a large intron of a house-keeping gene, and incubated the mixture for half day under renaturation conditions.

Read the experimental summary carefully and answer the following questions:

  1. During incubation period, is there any probability of formation of DNA-RNA duplex? Support your answer with a reason.
  2. If you have to perform the same experiment by taking total cytoplasmic RNA from the same cells. Is there any probability of formation of RNA–DNA duplex in this experiment? Support your answer with a reason

Ans

  1. In an experiment performed by a scientist, there is probability of formation of DNA-RNA duplex. Some RNAs will hybridise because all of them have not been completely processed and hence; will still contain the intron sequence.
  2. If cytoplasmic RNA is used in the same experiment, there is no probability of formation of DNA-RNA duplex because all of the mRNA in the preparation have been processed as processing occurs in the nucleus of a cell.

Q.50 A biotechnologist has designed a synthetic gene which codes for an enzyme that degrades the herbicide glyphosate. If another biotechnologist wishes to introduce this gene into Arabidopsis plant and test for the resistance to glyphosate, how would he produce a transgenic plant extracting the synthetic gene by Agrobacterium tumefaciens mediated transformation?

Ans

The possible steps involved would be:

  1. First of all, he would construct a chimeric gene containing a synthetic gene fused to a plant promoter and a plant transcription termination and poly-adenylation signal.
  2. The, he would insert this chimeric gene into the T-DNA of a Ti plasmid containing a dominant selectable marker gene, which provides resistance to kanamycin and introduce into the cells of Agrobacterium tumefaciens by the method of transformation.
  3. After that he would co-cultivate tissue explants from Arabidopsis plant and cells of Agrobacterium tumefaciens, and extract the recombinant Ti plasmid.
  4. Then, he would select the plant cells carrying T-DNAs inserted into their chromosomes on medium containing kanamycin.
  5. Ultimately, he would regenerate the transgenic plants from the transformed cells and test them for their resistance to glyphosate.

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