Chapter 13 Genetic Engineering

13-1 Changing the Living World

Selective Breeding

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

Increasing Variation
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)

13-2 -13-4 - Manipulating DNA

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?