presentasi kloning (091109)
DESCRIPTION
tugasTRANSCRIPT
CLONING
Etty Widayanti, SSi. MBiotech.Bagian Anatomi Sub Bagian Biologi
Fak. Kedokteran Univ. YARSI
Genetic Engineering
- gene splicing, gene cloning, molecular cloning- process cutting a gene out of a DNA strand and inserting the gene into another DNA strand.Clones Genetically identical organisms or molecules
derived from a common ancestor
Cloning Plants from Single Cells
Cloning Animals
Animals were cloned more than 20 years ago
Two techniquesEmbryo splittingNuclear transfer
www.biotechnologyonline.gov.au
Cloning by nuclear transfer
don’t live as long
not carbon copies/identical
develop diseases early
very low success rate - 0.1 - 3%
Dedifferentiation/reprogramming may not be complete or accurate
Problems
Gene Cloning
All identical to starting gene - CLONES
Gene
Host
Cloning vector Recombinant DNA
Started with: few copies
GOAL: To get enough copies of the gene to manipulate
Multiply
Ended with: Many copies.
Steps in cloning a single piece of DNA
1. Appropriate restriction sites
2. Cut vector and foreign DNA with RE
3. Run on gel to separate fragments
4. Isolate specific fragment
5. Ligate with cut vector
6. Transform host bacteria Selection
7. Grow up colonies
8. Isolate plasmid DNA
9. Cut with RE to confirm presence of foreign DNA
10. Run on gel to identify recombinant plasmids
Gene Cloning
Vector cloning Restriction Endonuclease
(restriction enzymes) and ligase
Host cell Transformation
Cloning Vectors- carrier for DNA during the recombinant
DNA process.
- plasmid-piece of free-floating DNA in thecytoplasm of bacteria.
- double-stranded, circular molecules thatreplicate independently of the chromosome.
Vector: molecule of DNA which is used to carry a foreign gene into a host cell
Promoter gene - A sequence of bases in a nucleic acid
strand, that serves as a signal to start transcription.
Chromosomal DNA construct – The gene of interest.
Antibiotic resistant gene - Are used as a marker system for
transformed cells.
Marker gene – A gene that identifies which organisms have been successfully transformed.
Cloning Vectors
Endonucleases type of enzyme in DNA strand.
produced nucleic acid strand breaks interior of nucleic acid strand.
restriction endonucleases-enzyme produced by bacteria that is used in recombinant DNA.
cuts open bacterial plasmid.
ex: EcoRI, BamHI, HindIII, HindII, PstI
Gene construct engineered to plasmid with ligasees.Plasmids back to bacterium.
EcoR1 : E. coliPstI : Providencia stuartiiHindIII : Haemophilus influenzaNotI : Norcardia otitidis-
caviarum
Common Restriction Enzymes
G
CCTAG
GATCC
G
GATCC
G
G
CCTAG
Inserting foreign DNA using restriction enzymes
GATCC
G
G
CCTAG
BamHI BamHI
Ligase
Forming recombinant DNA:
ligation
Competent cell (host cell)
Definition- a cell that is capable of taking up
DNA
Transformed cell- cell with new DNA
Definition- process of introducing free DNA into bacteria.
Transformation
Methods of Transformation
Electroporation- Electrical shock makes cell membranes
permeable to DNA- The use of an electric shock to
momentarily open or disrupt cell walls
Calcium Chloride/Heat-ShockChemically-competent cells uptake DNA
after heat shock
Conjugation the contact of bacteria that involves the
exchange of DNA with a mating tube.
Other Processes
Agrobacterium Transformation
• Agrobacterium tumefacians is a bacterium that causes a
disease known as crown gall in plants.• Infects plants by transferring its genetic material into
plant cell.• Agrobacterium transformation is the most common
technique for genetically engineered plantsBallistic gene transfer
Ballistic Gene Transfer - the use of tiny DNAcoatedprojectiles as carriers. It is important to transport DNA through the walls of intended recipient
cells.Projectiles are often known as micro projectiles Ballaistic transformation is done by using a ‘gene gun’ the gene gun has been useful in creating agricultural crops.
Host cells
Why use bacteria?
Size: Bacteria are unicellular, making them easy to work with. Multicellularorganisms are more complex and every cell would need to contain the desired genetic alteration.
Reproduction: The faster a model organism reproduces, the more generations of offspring can be quickly produced.
Safety: E.coli strain HB101; K-12 does not make people sick.
Gel electrophoresis
-ve
+ve
Size separation4.0 kb
3.0 kb
2.0 kb
5.0
3.5
2.8
2.4
1.5
2.1
Log
(kb
)
Distance migrated
Gel electrophoresis system or “gel box”
UV illumination of stained DNA fragments
separated in an agarose gel by electrophoresis
Separating and purifying DNA fragments: gel electrophoresis
DNA is negatively charged, moves to the (+) pole in electric field
Ethidium bromide intercalates DNA,
fluoresces in UV light
We can insert the gene into cells – Now what?
Selecting for transformed cells and amplifying the
product
Basic Steps
Identify the transformants Isolate transformed colonies Amplify the product
Identifying transformants
Vectors containing antibiotic resistance genes can be used
Those that took up the vector will now express antibiotic resistance
Ability to metabolize substances included in media
Multiplication of the host cells by cloning
Large scale fermenters by cloning
All genetically identical because of asexual reproduction
References
Brown, T.A. 1990. Gene cloning: An introduction. Chapman & Hall, London.
Campbell, N.A., Reece, J.B. and Mitchell, L.G. 2004. Biologi. Jilid ke-3. Ed ke-5. Penerbit Erlangga, Jakarta.
Old, R.W. And Primrose, S.B. 2003. Prinsip-prinsip manipulasi gen: Pengantar rekayasa genetik. Penerbit Universitas Indonesia, Jakarta.
Watson, J.D., Tooze, J. And Kurtz, D.T. 1988. DNA rekombinan: Suatu pelajaran singkat. Terj dari Recombinant DNA, oleh Gunarso, W. Penerbit Erlangga, Jakarta.