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.

Amino Acid Chart

Geologic Time Scale

Geologic Time is the time scale of the history of the earth and its life.

Geologic Time Scale

Time Span	Geologic Time Period	Major Biological Event(s)
5.7-4.5 BYA*		Origin of the Earth
	[Precambrian]	Origin of life on Earth
3.5-1.5 BYA	Archaean Era	“Ancient” Era
About 3 BYA		Origin of photosynthesis—oxygen in the atmosphere—followed by the first and possibly greatest extinction period as anaerobic life forms succumbed to the poisonous effects of molecular oxygen.
About 2 BYA		First eukaryotic organisms
1.5-.57 BYA	Proterozoic Era	“First Animal” Era
About 1 BYA		First multicellular organisms
700-570 MYA**		The Ediacaran Fauna
570-225 MYA	Paleozoic Era	“Ancient Animal” Era
570-500 MYA	Cambrian Period	Cambrian explosion; origin of many kinds of marine invertebrates, including Trilobites. All modern phyla of invertebrates appeared, along with a number of phyla which are no longer found on Earth.
500-425 MYA	Ordovician Period	First vertebrates (all aquatic); First life on land (plants).
425-405 MYA	Silurian Period	Rise of fish; Agnatha (jawless fish) and Placodermi (armored fish)
405-345 MYA	Devonian Period	Often called the Age of Fishes.  Modern classes of fish appear (Osteichthes and Chondrichthes), First movement of animals onto land (Arthropods). Insects appear by 400 MYA. First Amphibia appear late in the Devonian.
345-280 MYA	Carboniferous Period	Often called the Age of Amphibia. Amphibia diversify on land; first reptiles appear. Also often called the Age of Ferns. The dominant plant forms were the Lycopods, members of the Fern Allies. These plants formed the Earth’s first forests, and their remains produced major deposits of fossil fuels.
280-225 MYA	Permian Period	Amphibia decline, reptiles increase. Mammal-like reptiles appear. Ancient continents coalesce to form the super-continent Pangaea.
225 MYA		Permian Extinction: During this period of time, 50% of all families of life on Earth became extinct. It is estimated that this meant the extinction of up to 96% of all species.
225-65 MYA	Mesozoic Era	“Middle Animal” Era; The Age of Dinosaurs
225-197 MYA	Triassic Period	First dinosaurs, protomammals give rise to first true mammals.
197-135 MYA	Jurassic Period	Dinosaurs at height. First placental mammals. First birds.
135-65 MYA	Cretaceous Period	Dinosaurs still predominant; mammals abundant, but tiny and nocturnal insectivores. Flowering plants appear, leading to great adaptive radiation among insects.
65 MYA		Cretaceous/Paleocene Discontinuity (K-T Boundary): 70% of all animal species become extinct, including most of the dinosaurs. All kinds of living things were affected by this mass extinction, including plants. A large percentage of the plant species on Earth became extinct, including the dominant group of phytoplankton.

Time Span	Geologic Time Period	Major Biological Event(s)
65-0 MYA	Cenozoic Era	“Recent Animal” Era; The Age of Mammals
65-2 MYA	Tertiary Period
65-54 MYA	Paleocene Epoch	Beginning of dominance of mammals; primitive primates appear. Grasses and early grazers appear
54-35 MYA	Eocene Epoch	All modern mammalian orders exist; early Cetaceans appear.
35-23 MYA	Oligocene Epoch	All modern mammalian families exist; first modern birds and apes appear.
23-6 MYA	Miocene Epoch	Whales appear.
6-2 MYA	Pliocene Epoch	Large extinction of early mammals; probable separation of hominid line from other hominoids.
2-0 MYA	Quaternary Period	Age of Hominids (Man and close ancestors)
2-.01 MYA	Pleistocene Epoch	Early human evolution; appearance of Homo sapiens.
10-0 TYA***	Holocene Epoch	Rise of human civilization/

*BYA = Billion Years Ago

**MYA = Million Years Ago

***TYA = Thousand Years Ago