DNA Techonogy

DNA Technology refers to a wide range of techniques used to study, improve, create or manipulate the genetic material. Genetic engineers can now employ DNA technology to identify genes that control a desired trait, extract them, copy them, and insert into organism.

Recombinant DNA Technology
   - It refers to the process of creating a DNA molecule by joining together DNA or segments of DNA    
   obtained from 2 different species.

  - Restriction enzyme is very specific in cutting at the same sequence no matter where the DNA came from.

  - The bacterial cells are allowed to reproduce; as a result, several copies of the inserted eukaryotic gene  
    are made. The process by which multiple copies of the desired gene are produced is called gene cloning.

-Gentically modified organisms (GMOs) also known transgenics, are produced through recombinant DNA techonology. The glow-in-the-dark tobacco has a firefly gene. The flourescent pigs and mice have a jellyfish gene. Bt corn has insect-resistant gene from the soil bacterium thuringiensis.

SOME APPLICATIONS OF DNA TECHNOLOGY

a. Medicine

- DNA technology has been used for diagnosis and treatment of diseases, correction of genetic disorders and manufacture of hormones and other pharmaceutical products.

- Detectible gentic disorders may be corrected through a procedure called gene therapy. It involves:
1. extraction of few cells from the patients;
2. additional of functional genes in cells of the patient that carries defective ones; and
3. reintroduction of the corrected cells into the patients.

- Nonpathogenic viruses can be engineered to contain genes that manufacture the protein-carbohydrate coat of herpes and hepatitis viruses. The nonpathogenic virus can be used as vaccine for immunization against herpes and hepatitis, allowing the human body to produce antibodies against coat, without the disease-causing ability of the real herpes and hepatitis viruses.

b. Agriculture

- Bacteria were successfully transformed using the cow gene that controls production of the growth  hormone. The transgenic bacteria can produce the growth hormone in commercial quantities. The hormones are then injected into cows to increase body weight and milk production.

- Tomatoes were transformed with gene that prevents the production of ethylene which is a fruit-ripening plant hormone. Without ethylene, ripening of fruit is delayed, preventing spoilage during transport.

- Bt corn, potato, and cotton are genetically modified plants that received a gene from the soil bacterium Bacillus thuringiensis.This gene codes for the production of a protein that is converted into toxin in stomach of a specific group of insects. The toxin causes paralysis and death in caterpillars. With Bt crops, huge losses in agriculture due to insect pests may be prevented while reducing the use of chemical pesticides.

- Super salmon engineered with growth hormone gene from a large fish species grows so fast that it's 11 times heavier than the salmon caught in the wild or grown by conventional means.

c. Forensics

- In February of 1987, a woman was raped by unknown assailant. Tommie Lee Andrews was the major suspect but the case against him was weak. The victim could not identify the assailant who covered her head with a sleeping bag during the rape. There was a witness who never saw the rapist but can tell him apart even from a billion other men. The witness was DNA. The chromosomes of every human cell contain repeated fifteen-nucleotide segments called "minisatellites". These "minisatellites" are unique for each individual that the probability of 2 individuals being alike is 1 out of 10 billion. The DNA of the rapist's semen obtained from he victim after the rape was compared against the suspects's blood DNA. It was a perfect match. In November 1987, Tommie Lee Andrews became the first man convicted of crime using DNA technology.

SAFETY AND ETHICAL CONSIDERATIONS

- Pioneer Hi-bred International inserted genes from Brazil nuts into soybeans to increase their protein content. Some people allergic to Brazil nuts who ate the genetically engineered soybeans suffered allergic reactions.

- Designer crops, like Bt cotton, that manufactured pesticides or herbicides killed not only the insect pest pest and weeds, but also some beneficial insects. In Thailand, Bt cotton did show resistance to insect pests but beneficial insects like bees also died in the test fields.

- Some experimental animals became unstable and unwholesome. A few pigs engineered with human growth hormone developed arthritis, ulcer, blindness, and impotence. Some of the super salmon ended up with huge monstrous heads and died from poor eyesight and labored breathing. Dolly, the first mammalian clone, had to be put to sleep (killed) at the age of six in february 2003. She suffered from serious respiratory disease known only to occur more often in older sheep.