breeding of organisms to produce certain desired traits in their offspring. http://www.youtube.com/watch?v =_ZbnfjLoDSY
The differences among breeds of dogs are great. Where did these differences come from? Humans use selective breeding to produce animals with certain desired traits. Selective breeding allows only those animals with wanted characteristics to produce the next generation.
American botanist Luther Burbank developed more than 800 varieties of plants using selective breeding methods. One method Burbank used was hybridization, crossing dissimilar individuals to bring together the best of both organisms. Hybrids—the individuals produced by such crosses—are often hardier than either of the parents.
To maintain desirable characteristics in a line of organisms, breeders often use inbreeding, the continued breeding of individuals with similar characteristics. The many breeds of dogs are maintained using inbreeding, ensuring that the characteristics that make each breed unique are preserved.
Application of a technological process, invention, or method to living organisms.
It is relatively easy to extract DNA from cells and tissues. The extracted DNA can be cut into fragments of manageable size using restriction enzymes. These restriction fragments can then be separated according to size, using gel electrophoresis or another similar technique.
Once biologists find a gene, a technique known as polymerase chain reaction (PCR) allows them to make many copies of it. 1. A piece of DNA is heated, which separates its two strands.
2. At each end of the original piece of DNA, a biologist adds a short piece of DNA that complements a portion of the sequence. These short pieces are known as primers because they prepare, or prime, a place for DNA polymerase to start working.
3. DNA polymerase copies the region between the primers. These copies then serve as templates to make more copies. 4. In this way, just a few dozen cycles of replication can produce billions of copies of the DNA between the primers.
Genetic Engineering- any technique used to identify or change genes. Examples: Corn, Tomato, Cows Gel Electrophoresis- using electric currents to separate fragments or bases of DNA. Gene Cloning- making an exact copy of a living organism. Example- Dolly- first cloned mammal from a body cell.
Stem Cells- primitive cells that can be cultured into tissues or organs. Examples: Adult- umbilical cord Embryonic- developing embryos Human Genome Project- project to map every human chromosome.