1. Chapter 13 – Genetic Engineering
Has Bonnie been bred by selective breeding?

2. Selective Breeding
Choose organisms with the desired traits and breed them, so the next generation also has those traits
Nearly all domesticated animals and crops
Luther Burbank ( ) developed >800 diff varieties of plants in his lifetime

3. Hybridization Breed two dissimilar organisms
In plants – often results in better lines – hybrids are larger, stronger, etc
In animals – hybrids produced may be weaker and sterile
Ex – wolf x dog ---- weak wolf-dog
Ex – horse x donkey ---- mule (sterile)

4. Lion x Tiger
= Liger
Horse x Donkey = Mule

5. Inbreeding
Breeding two organisms that are
very similar to produce offspring
with the desired traits.
Ex – dog breeds
Risks – might bring together two individuals that carry bad recessive genes – many purebred dogs have genetic disorders that mutts don’t get.

6. Increasing Variation
Induce mutations – the ultimate source of genetic variations among a group of organisms
Mutagens used – radiation and chemicals
Some organisms are formed that have more desirable variations.

10. Producing new kinds of bacteria
Can expose millions of bacteria at one time to radiation – increases chances of producing a successful mutant.
Ex – bacteria that can digest oil have been produced this way
                                                                                                                                 

11. Producing new kinds of plants:
Drugs that prevent chromosomal separation in meiosis have been used to create plants that have more than two sets of chromosomes (2n). These are called polyploid plants.
Ex – bananas, citrus fruit, strawberries, many ornamental flowers
                                             
Diploid corn
Tetraploid corn

13. Page 64-66

14. Manipulating DNA – tools of the molecular biologist
DNA extraction – open the cells and separate DNA from all the other cell parts.
Remember the onion lab?

15. Cutting DNA
Use restriction enzymes
– each one cuts DNA at a
specific sequence of nucleotides.
This will make different
lengths of DNA

16. Separating DNA – Gel Electrophoresis
Place fragments at one end of a porous gel – we use agarose gel
Apply an electric current – The DNA is negatively charged and will travel toward the positive end of the gel.
The larger pieces of DNA move slower, the smaller ones faster.
Used to compare genomes of different organisms or different individuals.
Also used to locate and identify one particular gene out of an individual’s genome.

18. Click here for animation about gel electrophoresis

19. Using the DNA Sequence Sequence can be read, studied, and changed.
Techniques used to study DNA sequences:
Use DNA polymerase and the 4 DNA bases to produce a new DNA strand complementary to unknown strand – some of the bases are dyed.
Dye-labeled strands are then separated using gel electrophoresis and the order of the bands tells the DNA sequence of the unknown strand.

20. Cutting and Pasting – make recombinant DNA (DNA from two different organisms).
Cut out the gene to be inserted, use same restriction enzyme to cut the receiving DNA strand, attach the two DNA strands

21. Making Copies
Polymerase Chain Reaction (PCR) is used to make many copies of the same piece of DNA like a photocopy machine makes copies of papers.
This is useful if there is only a very small sample of DNA available (as that found in a small blood drop at a crime scene)

22. Cell Transformation p. 64-66
A cell takes in DNA from outside the cell and that DNA then becomes part of the cell’s DNA.
Bacteria – place DNA in the solution that bacteria live in, and some of that DNA will be taken in by the bacteria cells.

23. Bacteria Transformation using Recombinant DNA
Cut a gene with a restriction enzyme out of a human cell (ex – gene for insulin or growth hormone work well)
Cut a bacterial plasmid using the same restriction enzyme (DNA ends will be complementary)
Insert Human gene into bacterial plasmid
Insert plasmid back into bacterial cell
Bacteria will multiply, and all offspring will have that gene – these bacteria will then follow the directions of the human gene and make the protein coded for (insulin or human growth hormone)

24. Transforming Plant Cells
Use bacterial plasmid to insert desired gene into DNA of a plant

26. Transforming Animal Cells
Directly inject DNA into the nucleus of an egg – it will become part of the chromosomes.
Has been used to replace specific genes.
Glowing mouse cells in embryos that were made from sperm given the gene for bioluminescence from jellyfish – now all the cells glow!

27. Applications of Genetic Engineering
Gene for luciferase was isolated from fireflies and inserted into tobacco plants – they glowed!
Transgenic organisms – contain genes from other species
A transgenic mouse, which carries a jellyfish gene, glows green under fluorescent light.  

28. Transgenic Organisms Bacteria - Make human proteins like insulin
Plants – 52% of soybeans, 25% of corn in US in year Some produce natural insecticide, some resist weed-killers, may soon be used to produce human antibodies; rice with vitamin A.

29. Animals – mice with immune systems like humans; farm animals that grow faster and larger with extra copies of growth hormone genes; animals with leaner meat; chickens resistant to bacterial infections.

30. Cloning Clone – member of a population of genetically identical cells
produced from a single cell.
1996 – Dolly cloned –
1st mammal (sheep) cloned.
She got arthritis several years
earlier than most sheep
Died in 2003

31. The End