1. Genetic Engineering

2. Selective Breeding
Choosing animals/organisms with desired characteristics to breed and produce offspring
Goal: to pass desired traits to next generation of organisms
Examples: Dogs, Cats, Farm animals and Crop plants

3. Selective Breeding
Hybridization- Crossing dissimilar individuals to bring together the BEST traits of BOTH organisms
HOPEFULLY, offspring of cross are HARDIER than either parent
Example: in Crop plants combine disease resistant of one with food-producing capacity of another

4. Selective Breeding
Inbreeding- Continued breeding of individuals with similar characteristics
Seeking to maintain desired characteristics of organism are maintained over many generations
Risk- Since members of breed genetically similar; may increase chances of recessive disease being expressed
First Cousins NOT ALLOWED to marry!

6. Selective Breeding
Increasing variation- breeders do so by DELIBERATELY inducing mutations (ultimate source of genetic variability)
Using mutagens to increase variability!
Examples: new bacterial strains (clean up oil-WOW) or new kinds of flowers
Polyploidy- accepted in plants; more than two chromosomal sets

7. DNA Manipulation
Until very recently, plant and animal breeders were unable to modify the genetic code of organisms
Forced to work with inherent variation in nature
Even with addition of variation via mutations, changes in DNA produced were random and unpredictable

8. DNA Manipulation
TODAY, scientists can use their knowledge of DNA structure and its chemical properties to alter the sequence of DNA
Techniques include: DNA extraction, cut DNA into smaller pieces, identify DNA sequence one base at a time as well as make unlimited copies of DNA

9. Genetic Engineering
Genetic Engineering- making changes in the DNA code of a living organism
1. DNA extraction- cells are opened and DNA is separated from other cell parts
2. Restriction enzymes- proteins that preferentially cut DNA at a specific nucleotide sequence
3. Gel electrophoresis- Load DNA onto an end of a porous gel and apply an electric charge, separating DNA fragments based on size

16. Recombinant DNA
Combining DNA from different organisms/different sources
Using SAME restriction enzyme (cut and paste), take a gene from one organism and attach it to the DNA of another organism

19. Cell Transformation
Transformation- A cell takes in DNA from outside the cell. This external DNA becomes part of the cell’s DNA
Plasmid- Foreign/transforming DNA added to a small, circular DNA molecule

20. Cell Transformation 2 essential features:
1. Plasmid has DNA sequence serving as an origin of replication; if plasmid gets inside bacterial cell, sequence ensures plasmid that it will be replicated
2. Contains genetic marker- allows one to distinguish bacteria containing/transformed by plasmid vs. those that have not-Antibiotic resistence gene

25. Transforming Plant cells

26. Gel electrophoresis
After restriction digestion, a mixture of DNA fragments (different sizes) is loaded onto one end of a gelatin material
An electric voltage is applied to the gel
DNA molecules (negatively charged-WHY?) move toward the positive end of gel

27. Gel electrophoresis
The smaller the DNA fragment, the faster (and further on the gel) it moves
Gel electrophoresis used to:
compare DNA sequences of different organisms or different individuals within species
Locate and identify one particular gene out of millions of genes in individual’s genome

32. Using DNA sequence
Knowing organism’s DNA sequence, one can do the following:
1. Study specific genes
2. Compare genes to other organisms genes
3. Identify functions of different genes and gene combinations

33. Reading DNA sequence
Small, single stranded DNA pieces placed in test tube with DNA polymerase
A supply of all four “free” nucleotide bases is then added, along with one “labeled” base (label with fluorescent dye)
When DNA polymerase adds labeled base, replication is terminated

34. Reading DNA sequence
When using all 4 “labeled” bases-each with different fluorescent color-a series of tiny DNA fragments is created
Separate fragments via gel electrophoresis
Pattern of colored bands tells exact sequence of bases in the DNA

38. Polymerase Chain Reaction
PCR- Making multiple copies of a specific gene of interest; a photocopy machine stuck on “print.”
1. At each end of DNA “gene of interest” is placed a COMPLEMENTARY DNA sequence (known as a “primer” priming DNA replication; Start point of DNA polymerase!
2. DNA heated to high temperature to separate two template strands

39. Polymerase Chain Reaction
3. Next, DNA solution is cooled, allowing primers to ANNEAL to template strands (single stranded DNA)
4. DNA polymerase starts making copies of region between primers
5. NOW, primers themselves can then serve as templates to AMPLIFY “gene of interest” that lies between primer sequences