Genetic Engineering. Selective breeding – controlled breeding for desired characteristics; takes advantage of naturally occurring genetic variation – Fig. 13 – 1 What are some organisms that are good examples of selective breeding?
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Selective breeding – controlled breeding for desired characteristics; takes advantage of naturally occurring genetic variation – Fig. 13 – 1
What are some organisms that are good examples of selective breeding?
1. hybridization – breeding technique that involves crossing dissimilar individuals to bring together the best traits of both organisms
2. inbreeding – mating between organisms that are genetically similar: promotes preservation of desired characteristics; decreases genetic variation
1. Bacteria – radiation or chemicals can cause “beneficial mutations” – Fig. 13-3
2. Plants – chemicals that prevent chromosomal separation lead to polyploidy (What advantages do these plants have?)
3. Induced mutations can also be used to study the function of proteins
Reading the sequence allows the study of specific genes – Fig. 13 -7 (Sanger Sequence)
1. Start with a single strand of DNA with unknown sequence
2. Mix this strand with DNA polymerase and a lot of nucleotides; some of the nucleotides are “tagged” with dye
3. each time a “tagged” nucleotide is added replication stops
4. Using gel electrophoresis complementary DNA strand is “read”
A technique by which any segment of DNA can be quickly amplified (copied many times) – Fig. 13-8
1. DNA is separated and added to a mixture of nucleotides and enzymes
2. New complementary strands are made
3. Cycle is repeated many times
http://www.youtube.com/watch?v=JRAA4C2OPwg&feature=related PCR Animation
PCR Song http://www.youtube.com/watch?v=x5yPkxCLads
Some bacteria can take up naked DNA from the surroundings.
Plasmid – a small, circular, self-replicating DNA molecule separate from the bacterial chromosome
Assimilated foreign DNA is taken up by the plasmid
Offspring of the recipient bacterium will carry a new combination of genes
Genetic marker – a gene that produces a known protein that can be used to “mark” bacteria that have taken up foreign DNA
Plant Transformation – Fig. 13-10
Plasmids that normally infect plant cells can be used as carriers of foreign DNA
Whatever gene is taken up is then expressed by the plant cell
What are some advantages and disadvantages of this technology?
The bacterium can be used to introduce foreign DNA into plant cells. If the transformation is successful, the DNA will be integrated into one of the cell’s chromosomes.
Animal Transformation – Fig. 13-11
Eggs cells are large enough to take up foreign DNA
DNA is inserted manually and enzymes normally present in the cell to repair DNA help to insert the foreign DNA
Technique can be sued to study specific functions of a gene
Transgenic organisms contain genes from another species; possible because of the universal nature of the genetic code – Fig. 13-12
Microorganisms – easy to grow, divide rapidly, can be used to produce human proteins
Animals can be used to improve food supply, or to study effect of human diseases
Plants – genes can be implanted that provide plants with natural insecticides, or resistance to various chemicals
This transgenic tobacco plant, which glows in the dark, was grown from a tobacco cell transformed with the firefly luciferase gene. The plant illustrates how DNA from one organism contains information that can specify traits in another organism.
Cloning – A clone is a lineage of genetically identical individuals or cells
Basic cloning technique – Fig. 13-13 KNOW!!!
The adult sheep is Dolly. The lamb is Dolly’s first offspring., called Bonnie. The fact that dolly was cloned did ot affect her ability to produce a live offspring. Why might it be important for cloned animals to be able to reproduce?