Principal of genetic engineering & its applications

Principal of genetic engineering & its applications

1. Principal of genetic engineering & its applications in medicines BY Dr. Laraib Jamil Rph department of pharmaceutics University Of Balochistan

2. Genetic Engineering Genetic engineering is a process that alters the genetic make-up of an organism by either removing or introducing  DNA. DNA can be introduced directly into the host organism or into a cell that is then  fused  or  hybridized  with the host. (Hybridize: cross-breed (individuals of two different species or varieties).

3. Genetic engineering, sometimes called genetic modification, is the process of altering the  DNA in an organism’s  genome. This may mean changing one base pair  (A-T or C-G), deleting a whole region of DNA, or introducing an additional copy of a  gene. It may also mean extracting DNA from another organism’s genome and combining it with the DNA of that individual.

4. Plants, animals or micro organisms that have been changed through genetic engineering are termed genetically modified organisms or GMOs .  If genetic material from another species is added to the host, the resulting organism is called transgenic . If genetic material from the same species or a species that can naturally breed with the host is used the resulting organism is called  cisgenic. If genetic engineering is used to remove genetic material from the target organism the resulting organism is termed a knockout organism.

5. E xample

6. History  Genetic engineering as the direct manipulation of DNA by humans outside breeding and mutations has only existed since the 1970s. The term "genetic engineering" was first coined by Jack Williamson in his science fiction novel  Dragon's Island , published in 1951.

7. The first genetically modified organism to be created was a bacterium, in 1973. In 1974, the same techniques were applied to mice. In 1994 the first genetically modified foods were made available.

8. Genetic engineering has a number of useful applications, including scientific research, agriculture and technology. In plants, genetic engineering has been applied to improve the resilience(illness), nutritional value and growth rate of crops such as potatoes, tomatoes and rice. In animals it has been used to develop sheep that produce a therapeutic protein in their milk that can be used to treat cystic fibrosis, or worms that glow in the dark to allow scientists to learn more about diseases such as  Alzheimer’s.

9. Host organism : The organism that is modified in a genetic engineering experiment is referred to as the  host . Depending on the goal of the genetic engineering experiment, the host could range from a bacterial cell to a plant or animal cell or even a human cell.  Vector : The vehicle used to transfer genetic material into a host organism is called a  vector . Scientists typically use plasmids, viruses, cosmids(cos+plasmids), or artificial chromosomes in genetic engineering experiments.

10. How Does Genetic Engineering Works? To help explain the process of genetic engineering lets take the example of insulin, a  protein  that helps regulate the sugar levels in our blood . Normally  insulin  is produced in the  pancreas, but in people with type 1  diabetes  there is a problem with insulin production. People with diabetes therefore have to inject insulin to control their blood sugar levels.  Genetic engineering has been used to produce a type of insulin, very similar to our own, from yeast and  bacteria  like  E. coli .   This genetically modified insulin, ‘Humulin’ was licensed for human use in 1982. 

11. The Genetic Engineering Process A small piece of circular DNA called a  plasmid  is extracted from the bacteria or yeast cell. A small section is then cut out of the circular plasmid by restriction enzymes, ‘molecular scissors’. The gene for human insulin is inserted into the gap in the plasmid. This plasmid is now genetically modified. The genetically modified plasmid is introduced into a new bacteria or yeast cell.

12. 5. This cell then divides rapidly and starts making insulin. 6. To create large amounts of the cells, the genetically modified bacteria or yeast are grown in large fermentation vessels that contain all the nutrients they need. The more the cells divide, the more insulin is produced. 7. When fermentation is complete, the mixture is filtered to release the insulin. 8. The insulin is then purified and packaged into bottles and insulin pens for distribution to patients with diabetes.

13. Application of genetic engineering in medicines : Genetic engineering has many applications to medicine that include the manufacturing of drugs, creation of  model animals   that mimic human conditions and  gene therapy . One of the earliest uses of genetic engineering was to mass-produce human insulin in bacteria .  This application has now been applied to, human growth hormones,  follistim  (for treating infertility),  human albumin,   monoclonal antibody,   antihemophilic factors,   vaccines  and many other drugs.

14.  Mouse  hybridomas, cells fused together to create  monoclonal antibodies, have been humanised through genetic engineering to create human monoclonal antibodies .  Genetically engineered viruses are being developed that can still confer immunity, but lack the  infectious sequences.

15. Genetic engineering is used to create animal models of human diseases.  They have been used to study and model cancer (oncomouse), obesity, heart disease, diabetes, arthritis, substance abuse, anxiety, aging and Parkinson disease.

16. Potential cures can be tested against these mouse models. Also genetically modified pigs have been bred with the aim of increasing the success of  pig to human organ transplantation. Gene therapy is the genetic engineering of humans, generally by replacing defective genes with effective ones.  Clinical researchers  using  somatic  gene therapy has been conducted with several diseases, including X-linked SCID ,  chronic lymphocytic leukemia (CLL ),  and Parkinson's disease.

17. There are also concerns that the technology could be used not just for treatment, but for enhancement, modification or alteration of a human beings' appearance, adaptability, intelligence, character or behavior. Right now, scientists are working on designing foods that contain vaccines.  Vaccines  create immunity, where our body recognizes a virus and is able to fight it off without us getting sick. Instead of getting injections, which can be tough to transport and administer to remote countries where disease is most prevalent, scientists want to put it into their food.

18. One vaccine being studied is for hepatitis B. Hepatitis B is a virus that affects the liver. Tobacco plants have been engineered to make part of the virus, which when consumed by mice, causes immunity to the virus, just like a vaccine.

19. Research being done on potatoes, show that genes can be put successfully into potato plants that will make vaccines against cholera, diarrhea and hepatitis B. Scientists hope to be  able to genetically engineer bananas to have vaccines in them. The bananas would then be grown in developing countries, where disease such as cholera and diarrhea are very prevalent . This would be a much cheaper alternative to the wasteful process of a series of shots, throwing away costly syringes after every injection. About 300 million people are carriers of hepatitis B, which can cause liver failure and liver cancer. Diarrhea is a common cause of death in young children.

20. Alzheimer disease Scientists are using a special type of cell, called a stem cell, to grow new organs and replace damaged tissue.  Stem cells  are cells that are basically a blank slate and can become any other type of cell. They can be found in both embryos and adults. Scientists take the stem cells, put in healthy, normal DNA, and then put them into patients to replace their cells that have defective DNA. Manipulating stem cells is probably one of the most  recognizable form of genetic engineering in medicines.

21. In Alzheimer’s disease nerve cells or neurons start to be die off due to defective DNA. If doctors grow new neurons from patient’s stem cells, they could replace the dying cells in the brain with cell engineered to have normal DNA curing the disease.

22. Anemia The children with ADA (adenosine deaminase) deficiency die before they are two years old. Bone marrow cells of the child after removal from the body were invaded by a harmless virus into which ADA has been inserted. Erythropoetin, a genetically engineered hormone is used to stimulate the production of red blood cells in people suffering from severe anaemia.

23. Production of blood clotting factor Normally heart attack is caused when coronary arteries are blocked by cholesterol or blood clot. plasminogen is a substance found in blood clots. Genetically engineered tissue plasminogen activator (tPA) enzyme dissolves blood clots in people who have suffered heart attacks. The plasminogen activator protein is produced by genetech company which is so potent and specific that it may even arrest a heart attack underway.

24. Cancer Cancer is a dreaded disease. Antibodies cloned from a single source and targetted for a specific antigen (monoclonal antibodies) have proved very useful in cancer treatment. Monoclonal antibodies have been target with radioactive elements or cytotoxins like Ricin (Ricin is a highly toxic, naturally occurring lectin produced in the seeds of the castor oil plant, Ricinus communis. A dose of purified ricin powder the size of a few grains of table salt can kill an adult human). Such antibodies seek cancer cells and specifically kill them with their radioactivity or toxin.