Q. 1. What are the three critical research areas of biotechnology?
Ans. The critical research areas of biotechnology are:
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Research areas of bio-technology
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1. Providing best catalyst:
To provide best catalyst in the form of a microbe or pure enzyme, e.g. insulin.
2. Creating optimal conditions:
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To create optimal conditions through engineering for a catalyst to act.
3. Down stream processing:
To provide down stream processing technologies to purify the protein or organic compound produced by the microbe.
Q. 2. Compare and contrast the advantages and disadvantages of production of genetically modified crops.
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Ans. The production of the crops for high food production by traditional methods has its own problems.
It needs the inputs of agrochemicals such as synthetic chemical fertilizers and pesticides to ensure the productivity.
It has its limitations as well. It cannot depend on the agrochemicals throughout. It needs better varieties, which is possible by GM crops.
Advantages of these GM crops are:
1. They are tolerant to abiotic stresses.
2. They are less dependant on chemical pesticides.
3. They have increased efficiency of mineral usage.
4. They have enhanced nutrition value of food.
5. They have reduced post harvest losses.
Disadvantage being that they are not readily acceptable by farmers and people by large as they pose an ecological insecurity of biodiversity.
Q.3. What are cry proteins? Name an organism that produce it. How has man exploited this protein to his benefit?
Ans. Cry—proteins are toxins produced by the gene by same name in bacteria — Bacillus thuringiensis.
On introducing this gene into the plant cry protein is produced by the plant, e.g. Bt cotton. These proteins have been exploited by human to develop biopesticide.
There by controlling the pestillance and increase in crop productivity and reduction on dependance of chemical pesticides.
Q. 4. What are transgenic bacteria? Illustrate using any one example.
Ans. Bacteria that have been manipulated plasmid are called transgenic bacteria. Such bacteria have a forcing gene linked to the plasmid and they are used as vectors to introduce it to the host plant.
For example-Agrobacterium. It was manipulated and nematode specific genes were introduced through it to the host plant.
The host plant cells produced both sense and antisense RNA. These two RNA’s being complementry to each other formed a double stranded (ds RNA) that initiated RNAi.
Resulting in RNA interference in silencing the specific mRNA of the nematode. As a consequence of it the nematode could not survive in the transgenic host expressing the specific RNAi. The plant is thus protected from the parasite.
Q. 5. (i) What is RNAi?
(ii) How does the process work in the cells?
(iii) Mention its application in plants?
Ans.
(i) RNAi:
RNA interference (RNAi) is the process of cellular defense in all eukaryotic organisms.
(ii) The RNA produced by the cell involves the silencing of the specific mRNA due to complementry dsRNA molecule. This molecule binds to the mRNA and prevents the translation (silencing).
(iii) This method has been used to develop transgenetic plants that are pest resistant, to a nematode Meloidegyne incognita. This pest infects tobacco plant and reduces the yield.
Q. 6. What are the shortcomings of insulin obtained from slaughtered animals? How it has been overcome?
Ans. The insulin obtained from the slaughted animals pancreas were earlier given to diabetic patients.
As it was sourced from other animals such as cattle, pigs. The foreign protein’ caused allergy to the patients. Now insulin produced by genetic engineering of E. coli is used.
Q. 7. Briefly mention the structure of normal insulin. Which technique was used by Eli lilly an American Co. to prepare a mature insulin?
Ans. Mammalian insulin (Human) has three polypetides in the insulin. The insulin is produced in preform as prohormone and it is made functional/Nature by deleting the C peptide chain.
rDNA technique was used by the company. The company prepared two DNA sequences that coded for A and B chains of human insulin.
Then it was introduced into the plasmids of E. coli to produce these insulin chains. These chains were produced separately, extracted and combined by creating disulphide bonds to give human insulin.
Q. 8. What is gene therapy? Illustrate using the example of adenosine deaminase (ADA) deficiency?
Ans. It is the collection of a genetic defect identified/diagnosed in the child/embryo.
During this process a normal gene into the individual/embryo so that this gene takes over the function of the non-functional gene e.g. deficiency. Gene therapy in ADA deficiency follows these steps:
1. Culture of Lymphocytes:
Lymphocytes from the blood of patieht are cultured outside the body.
2. Introduction of ADAeDNA:
The next step involves the introduction ofADAeDNA (using a retroviral vectors into the lymphocytes.
3. Lymphocytes return:
The lymphocytes genetically transformed by this method are returned to the patient’s body.
As the lymphocytes live for certain period, patient needs such genetically engineered lymphocytes after some time again.
Q. 9. What is ADA deficiency? How is it cured? It is completely cured? Which method can provide a complete permanent cure?
Ans. Adenosine deaminase enzyme is required for functioning of the immune system in body. It is due to deletion of the gene for adenosine deaminase. In some children it is cured by:
(a) Bone marrow transplantation or
(b) Enzyme replacement therapy—in which functional ADA is given to the patient by injection. Both are not completely curative. If the gene isolated from marrow cells that produce ADA when introduced into early embryo then it could provide a permanent cure to this.
Q. 10. Mention a few molecular diagnosis techniques. Which one is considered to be very powerful?
Ans. Molecular diagnosis techniques
1. Recombinant DNA technology.
2. Polymerase chain reaction (PCR)
3. Enzyme linked immunosorbent Assay (ELISA)
PCR has been considered to be very powerful technique because of its amplication of DNA/RNA step. It has been used to early detection of —HIV, gene mutations even in cancer patients.
