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Chapter 13 Genetic Engineering
Lesson 1 Changing the living world Page 318 - 334
Selective Breeding
By Selective breeding, allowing only those animals with desired characteristics to produce the next generation, humans have produced many different breeds of dogs.
Key Point: Humans use Selective breeding, which takes advantage of Naturally occurring genetic variation in plants, animals, and other organisms, to pass desired traits on to the next generation of organisms.
As one of his tools, Burbank used hybridization, crossing dissimilar individuals to bring together the best of both organisms.
To maintain the desired characteristics of a line of organisms, breeders often use a technique known as inbreeding.
Inbreeding is the continued breeding of individuals with similar characteristics.
Increase Variation
Key Point: Breeders can increase the genetics variation in a population by inducing mutations, which are the ultimate source of genetic variability.
Lesson 2 Manipulating DNA
Key Point: Scientists use their knowledge of the structure of DNA and its chemical properties to study and change DNA molecules. Different techniques are used to extract DNA from cells, to cut DNA into similar pieces, to identify the sequence of base in a DNA molecule, and to make unlimited copies of DNA.
Genetic Engineering, making changes in the DNA code of living organisms, works almost the same way.
Hundreds of restriction enzymes are known, and each one cuts DNA at a specific sequence of Nucleotides.
gel electrophoresis, a mixture of DNA fragments is placed at one end of a porous gel, and an electric voltage is applied to the gel.
Such DNA molecules are sometimes called recombinant DNA because they are produced by combining DNA from different source.
Like a photocopy machine stuck on "Print" a technique known as polymerase chain reaction (PCR) allows biologists to do exactly that.
Lesson 3 Cell Transformation
Key Point: During transformation a cell takes in DNA from outside the cell. This external DNA becomes a component of the cell's DNA.
The foregin DNA is first joined to a small, circular DNA molecule known as a plasmid. Plasmids are found naturally in some bacteria and have been very useful for DNA transfer.
The plasmid has a genetic marker - gene that makes it possible to distinguish bacteria that carry the plasmid (and the foregin DNA) from those that don't.
Key Point: If transformation is successful, the recombinant DNA is integrated into one of the chromosomes of the cell.
Lesson 4 Applications of Genetic Engineering
The universal nature of genetic mechanisms makes it possible to contract organisms that are transgenic, meaning that they contain genes from other species.
Key Point: Genetic engineering has spurred the growth of biotechnology, which is a new industry that is changing the way we interact with the living world.
A clone is a member of a population of genetically identical cells produced from a single cell.
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