13-1 Changing the Living World
Takes advantage of naturally occurring
genetic variation in organisms & passes them on to next generation
Most domestic animals & crops have been produced this way (horses, cats, Burbank, potato)
Humans use this to pass desired traits on to the next generation of organisms
Hybridization = crossing dissimilar
individuals to bring together the best traits of both organisms
Produces hybrids - which are often hardier than parents
Hybrids have combined/desired traits of both parents
Inbreeding = continued breeding of
individuals with similar characteristics to maintain the desired characteristics
of a line (ex. pure breed golden retriever)
Has risks increases breed's susceptibility to disease & deformities
Breeders can increase variation in a population by inducing mutations
Mutation = any change in DNA
Mutations occur spontaneously, but rate can be increased through radiation & chemicals
Mutations produce new kinds of bacteria
ex. oil-eating bacteria (fig.13-3 p.320)
Mutations produce new kinds of plants Ex. day lilies, bananas, citrus fruits (fig. 13-4 p.321)
Genetic Engineering - manipulating DNA
Scientists use their knowledge of the structure of DNA & its chemical properties to study & change DNA molecules
Techniques are used to:
1. DNA Extraction
Removing the DNA from a cell so that it can be analyzed, sequenced, or combined with other DNA
In this photo, DNA from a strawberry is seen as bubbly white material at the top of the testtube.
2. DNA Sequencing
Once the DNA is extracted, it can be sequences and used to solve crimes, establish paternity, or test for genetic disorders
In gel electrophoresis, fragments of DNA are separated according to size.
The fragments are then compared to other data, to see if it matches. This image is sometimes called a "DNA FINGERPRINT"
3. Genetic Recombination - DNA can be combined from different organisms. The resulting organisms is called "genetically modified"
4. Cloning - DNA is extracted from one organism and is used to grow new cells (or a whole new organism)
Which raises the question: Should we clone human cells?