210 likes | 561 Views
Medically important substances produced by genetic engineering. Human Insulin- used to treat diabetesPast: extracted insulin from pancreas of cattle and pigsToday: Human insulin produced from bacteria. Medically important substances produced by genetic engineering. Vaccines: genetically engineered microorganisms used to make vaccinesHepatitis B vaccine: gene coding for viral protein in Hepatitis B cloned into bacteriaBacteria make viral proteinProtein used to make vaccine .
E N D
1. Lecture 8Genetic Engineering
2. Medically important substances produced by genetic engineering Human Insulin- used to treat diabetes
Past: extracted insulin from pancreas of cattle and pigs
Today: Human insulin produced from bacteria
3. Medically important substances produced by genetic engineering Vaccines: genetically engineered microorganisms used to make vaccines
Hepatitis B vaccine: gene coding for viral protein in Hepatitis B cloned into bacteria
Bacteria make viral protein
Protein used to make vaccine
4. Importance of Genetic Engineering Genetic traits transferred to plants
Pest resistant plants: engineered to resist natural pests
Examples: corn, cotton, potatoes
Bt-toxin: made in B. thuringiensis
Toxic to insects- dissolves their gut
Insert gene that makes Bt-toxin into plants’
Plants now make Bt-toxin
Transgenic: plants and animals into which new DNA has been introduced
5. Figure 9.5
6. Table 9.2
8. Genetic Engineering Transferring genes from one organism to another organism
Can be prokaryote to prokaryote
Prokaryote to eukaryote
Or eukaryote to prokaryote
Requires several things:
DNA of interest (must be isolated)
Various enzymes (restriction enzymes)
Suitable vector
Method for introducing DNA into new host
9. Isolating DNA of interest Cells are lysed (burst open)
As cells burst DNA is sheared into many pieces of varying lengths
Cut purified DNA into smaller fragments using restriction enzymes
10. Restriction Enzymes When DNA is cut with restriction enzymes the DNA pieces generated either have sticky (cohesive ends) or blunt ends
The cohesive ends will adhere to any piece of DNA with complementary sequence
11. Table 9.3
12. Vectors After isolating DNA, need to insert into vector
Vector- modified plasmid
Contains:
Origin of replication
Selectable marker, example: antibiotic resistance
At least one restriction enzyme recognition site
13. Figure 9.15
14. Generation of Recombinant Vector Recombinant vector: vector containing the piece of DNA you isolated
Put piece of DNA you isolated with sticky ends together with vector that is cut with same restriction enzyme
Sticky ends of isolated DNA will join to sticky ends of vector
Add ligase to glue isolated DNA to vector
16. Introducing recombinant vector into new organism Three steps:
Select a suitable host
Insert DNA into cells
Select for transformants
17. Select a suitable host Usually use E.coli
E.coli is easy to grow and much is known about it’s biochemistry and genetics
Also have known phenotypes such as sensitivity to certain antibiotics
18. Inserting the recombinant vector into bacterial cells Two methods:
DNA-mediated transformation
In this process competent cells take up DNA from surrounding environment
Electroporation
- Process involves treating cells with electric current that puts pores in the membrane so that plasmid can enter
19. Selecting for bacteria that contain vector First, grow bacteria on selective media- one that contains antibiotic
Remember, vectors contain genes for certain antibiotic resistance
20. Introducing vectors into eukaryotic cells If introducing to plant cells, can use the Ti plasmid
Advantage of this is that T-DNA and any genes you have inserted is naturally transferred from Agrobacterium to host cell
Other methods:
Electroporation: same as with bacterial cells
Gene gun: device that uses a gas pulse or other mechanism to propel DNA-coated gold particles into cell