Highlight any four areas where genetic modification of plants has been useful.
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.
What is a recombinant DNA vaccine? Give two examples.
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.
Why is it that the line of treatment for a genetic disease is different from infectious diseases?
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.
$$ \text { Discuss briefly how a probe is used in molecular diagnostics. } $$
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.
Who was the first patient to be treated with gene therapy? Why was the given treatment recurrent in nature?
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.