Biotechnology and its Applications Test - 40

The human insulin gene is inserted into the bacterium Escherichia coli with the help of vector DNA to produce synthetic insulin. It was developed by Herbert Boyer at the University of California.

Complete destruction of the potato crop by late blight (Phytophthora infestans) caused the 'Irish potato famine' in the middle of the 19th century, led to the search for resistant plants. Single genes for resistance to late blight (R genes) were discovered nearly 100 years ago in S. demissum, a wild potato species indigenous to Mexico.

Biotechnology is being used to address problems in all areas of agricultural production and processing. This includes plant breeding to raise and stabilize yields; to improve resistance to pests, diseases and abiotic stresses such as drought and cold; and to enhance the nutritional content of foods. 

• SCID or severe combined immunodeficiency is a primary immune deficiency. It is a genetic disorder characterized by the inhibition of the development of functional B cells and T cells, caused by numerous genetic mutations. 
• The gene coding for adenosine deaminase (ADA) which is necessary for the breakdown of purines gets mutated and this defective gene is now not able to encode ADA. 
• Lack of ADA causes accumulation of dATP that reduces ribonucleotides to generate deoxyribonucleotides. Without functional ribonucleotide reductase, lymphocyte proliferation is inhibited and such disorder is called SCID. 

A transgenic crop plant contains a gene or genes which have been artificially inserted instead of the plant acquiring them through pollination. The inserted gene sequence (known as the transgene) may come from another unrelated plant or from a completely different species. In many cases, the inserted DNA has to be modified slightly in order to correctly and efficiently express in the host organism. The pomato is a chimera produced by grafting a tomato plant and a potato plant, both of which are members of the Solanaceae family. Pomato plants make food production more efficient, as they maximize the amount of crops that can be produced on a piece of land. In addition, grafting can improve resistance to bacteria, viruses and fungi, attract a more diverse group of pollinators and provide a sturdy trunk for delicate ornamental plants.

Severe Combined Immunodeficiency is a primary immune deficiency characterized by the severe defects in both the T- and B-lymphocyte systems. This usually results in the onset of one or more serious infections within the first few months of life. These infections are usually serious and may even be life-threatening, they may include pneumonia, meningitis or bloodstream infections. There are several forms of SCID. The most common type is linked to the X-chromosome, making this form affect only males. Other forms of SCID usually follow an autosomal recessive inheritance pattern or are the result of spontaneous mutations. One of these other forms is linked to a deficiency of the enzyme adenosine deaminase (ADA) while other cases of SCID are caused by a variety of other defects.

A Ti or tumour inducing plasmid is a circular plasmid that is a part of the genetic equipment that Agrobacterium tumefaciens and Agrobacterium rhizogenes use to transduce its genetic material to plants. The Ti plasmid is lost when Agrobacterium is grown above 28$$^o$$C. Such, cured bacteria do not induce crown galls, i.e., they become avirulent.

Genetic engineering, also called as genetic modification, is the direct manipulation of an organism's genome using biotechnology. Human insulin is the name which describes synthetic insulin which is laboratory grown to mimic the insulin in humans. Human insulin is laboratory created by growing insulin proteins within E. coli bacteria (Escherichia coli). In the production of human insulin by bacteria, the human insulin gene is incorporated into the genetic material of these microorganisms. The mutant bacteria multiply forming lineages of insulin-producing bacteria. 

A transgenic mouse can be defined as a mouse whose chromosomes have been altered so that its genes contain foreign DNA. These genes are found in the nucleus of every cell of the body, so all of the mouse's cells contain the new DNA. The foreign DNA can come from any source and may be human, from another animal or from another mouse. The change in DNA usually means the cells gain a function, such as producing a new protein. For example, some transgenic mice produce contain proteins recognised by human immune cells, and these can be used to model particular aspects of disease. The mouse makes an excellent model for human disease because the organisation of their DNA and way their genes are expressed is very similar to humans. Their reproductive and nervous systems are like those of humans, and they suffer from many of the same diseases such as cancer, diabetes and even anxiety. Manipulating their genes can lead them to develop other diseases that do not naturally affect them and as a result, research on mice has helped understanding of both human physiology and the causes of disease.