Lecture 6 Thursday January 24 2008
- tumor
- food
- very similar to what humans do with insulin
- extract and use insulin
- kind of ingenius
tumefacians
- a natural tool for plant transformation
- cytokinins
- Humans independently discovered this phenomenon
- we use it for tissue cultures
tumors
- have a lot of cells
- protein
- bacteria lives in the tumor cell and eats the protein
Ti plasmid
- transfer DNA
- we can utilize the bacteria in tumors to insert DNA
- splice cut and insert
Recombinant DNA technology
- restriction enzyme can cut sequences of DNA at certain sports
- it can then be fused via a certain type of enzyme
- this key enzyme won the nobel prize and
- it can now be bought and sold at will
plasmids
- sticky end
- will form a double strand unless properly controlled
- complementary sequences
- recombinant DNA
modified Ti Plamid
- does not contain the genes for synthesis of particular proteins and plant hormones
- disarmed TDNA - it will not cause a tumor because when the introduced DNA was mixed its growth hormone gene was altered
- transformed plant cells - but this does not cause tumor formations
- a tumefacien transfer this modified T - DNA
- bacteria tries to insert DNA into nucleous
two types of modern bio-technology
- recombinant dna
- tissue culture
tissue culture
- whole plant is regenerated from this transformed cell using tissue culture techniques
- tissue hormone used to regenerate plant
- the origion of the plant is the cell that has been modified - transgenic or GM plant
- it expresses the gene of interest
- modified Ti Plasmid
selection marker gene
- antibiotic resistance genes are used as a selection marker
- this can not grow in the medium that contains antibiotics - e coli
- who ever if this bacteria gets a antibiotic resistance gene and the gene of interest than both can be insert via a plasmid
other genes cn be used as markers
- though antibiotic genes are common there are other methods
selection markers can be removed
- recombinant DNA is used
- gametes
- as long as the selection marker is resessive it will be breed out of existence but the gene of interest will be dominant and persist
- who wants to eat an antibiotic resistant gene?
- some researchers remove the DNA
two major ways of creating GM plants
- Using Agrobacterium tumefaciens
- particle bombardment
particle bombardment
- tiny metal particles coated with genes with desired characteristics are put into a particle gun and fired directly into the plant cells
- these genes are incorporated into the plant cell's DNA, and the cells are then grown into the full plants
- DNA is not fragile or mysterious it is simple, well understood and durable
- is dried it will become a powder - if water is added it will reform
- gene gun
- shoot the leaves
- by chance the inserted gene will combine with the rest of the DNA
- each event is different and independent
- plant was regenerated
- three individuals transgentic offspring are different
- this is because we cannot control where the gene was inserted
- the transgene's location in the genome is unknown and veries
- the amount of copies of the transgene varies
- expression of the gene may be double
Microinjection
- usually used for making transgenic mice
- mice with new genes added to their cells
- to make transgenic mice, special embryonic stem cells are grown in culture
- and then indiividual cells are injected wih DNA through microscopic glass needles
- remove egg nucleous, replace it with the one you want to propogate
- make a clone
- cannot be used in plants because of their thick cell wall
stem cells
Transgeneic mouse
- very useful to study mammalian gene function and regulation becasue analysis is carried out in a whole organism
- transgenic mice are lo used to model human diseases
- the transgenic mice (with the jelly fish protein) can be reinserted inutero
cloning is not transgeneic
- completely different
- cloning doesn't need recombinant DNA
- removed the entire dna set from the host nucleous
- then the donor's DNA was injected into the host
- the host gave birth to a clone of the donor
- a copy not a recombination
page revision: 0, last edited: 25 Jan 2008 14:35