Genetic Engineering

Genetic EngineeringSelective 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

Hybridization

X

Inbreeding

Genetic EngineeringIncreasing genetic variation can be accomplished by inducing mutations 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

Manipulating DNAHow do scientists change/manipulate DNA? 1. DNA extraction – remove DNA from the cell 2. DNA cutting – restriction enzymes “cut” DNA at very specific nucleotide sequences

Fig. 13-5

Restriction Enzyme http://www.youtube.com/watch?v=yc-s-WojU5Y&feature=related

Manipulating DNAHow do scientists change/manipulate DNA? 3. DNA separating – gel electrophoresis uses an electrical current to separate fragments of DNA based on size – Fig. 13-6

Gel Electrophoresis http://www.sumanasinc.com/webcontent/animations/content/gelelectrophoresis.html

Using the DNA sequenceReading 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”

Using the DNA sequenceSanger Sequencing Videos

http://www.youtube.com/watch?v=aPN8LP4YxPo&feature=related

http://www.youtube.com/watch?v=6ldtdWjDwes&feature=related

PCR – Polymerase Chain Reaction

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

PCR

PCR

http://www.youtube.com/watch?v=JRAA4C2OPwg&feature=related PCR Animation

PCR Song http://www.youtube.com/watch?v=x5yPkxCLads

Cell Transformation – taking up foreign DNA

Some bacteria can take up naked DNA from the surroundings.1. Plasmid – a small, circular, self-

replicating DNA molecule separate from the bacterial chromosome

2. Assimilated foreign DNA is taken up by the plasmid

3. Offspring of the recipient bacterium will carry a new combination of genes

4. Genetic marker – a gene that produces a known protein that can be used to “mark” bacteria that have taken up foreign DNA

Cell Transformation

Cell TransformationPlant Transformation – Fig. 13-101. Plasmids that normally infect plant cells

can be used as carriers of foreign DNA2. Whatever gene is taken up is then

expressed by the plant cell3. What are some advantages and

disadvantages of this technology?

Cell TransformationThe 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.

Cell TransformationAnimal Transformation – Fig. 13-111. Eggs cells are large enough to take up

foreign DNA2. DNA is inserted manually and enzymes

normally present in the cell to repair DNA help to insert the foreign DNA

3. Technique can be sued to study specific functions of a gene

Applications of Genetic Engineering

Transgenic organisms contain genes from another species; possible because of the universal nature of the genetic code – Fig. 13-121. Microorganisms – easy to grow, divide

rapidly, can be used to produce human proteins

2. Animals can be used to improve food supply, or to study effect of human diseases

3. Plants – genes can be implanted that provide plants with natural insecticides, or resistance to various chemicals

Transgeneic OrganismsThis 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.

Applications of Genetic Engineering

Cloning – A clone is a lineage of genetically identical individuals or cells1. Basic cloning technique – Fig. 13-13

KNOW!!!

Transgenic OrganismsIn early 1997, Dolly made headlines as the first clone of an adult mammal.

Transgenic OrganismsWhy did Dolly not look like her foster mother?

Transgenic OrganismsThe 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?