define genetic engineering/modification
the insertion of genes from one organism into the genetic material of another organism or changing of the genetic material of an organism
what is recombinant DNA
new DNA produced by genetic engineering technology that combines genes from the DNA of one organism with the DNA of another
what is reverse transcriptase
the enzyme used to make artificial copies of a desired gene by taking an mRNA molecule transcribed from the gene and using it to produce the correct DNA sequence
what are the steps in genetic engineering/modification
- isolate required gene using restriction endonuclease enzyme
- cut plasmid (which acts as a vector) with the same restriction endonuclease to make complementary sticky ends
- join plasmid and gene with DNA ligase to produce recombinant DNA
- insert the recombinant DNA back into the host cell
- the modified bacteria will now produce the protein coded for by the new gene
what is complementary DNA (cDNA)
DNA which can act as an artificial gene, made in reverse transcription
what are ‘sticky ends’
the area of base pairs left longer on one strand of DNA by specific restriction endonuclease making it easier to attach new pieces of DNA
what are plasmids
circular strands of DNA found in bacteria
what is replica plating
the process used to identify recombinant cells that involves growing identical patterns of bacteria colonies on plates with different media
what makes a good vector for replica plating
vector targets the right cell
ensures the desired gene is incorporated into the host genetic material so it can be activated
doesn’t have any adverse side effects
what are the steps in replica plating that help identify successful recombinant cells
- the bacteria containing desired gene also contain a marker gene (requires a specific amino acid to grow)
- colonies of bacteria are grown on a master plate on a complete medium
- master plate is inverted and pressed on sterile velvet surface leaving an imprint of the colonies
- this is repeated to create the replica plate however the medium of the replica plate does not contain the specific amino acid needed for growth
- replica plate is incubated and colonies which have not been genetically modified grow
- replica plate is compared to the master plate so genetically modified colonies can be identified and grown
what are gene guns
DNA is shot into the cell at high speed carried on minute gold pellets
some cells survive and accept the DNA
how can viruses be used to genetically modify cells
harmless viruses are engineered to carry desired gene and infect the cell with the DNA
what is liposome wrapping
gene to be inserted are wrapped in lipsosomes which fuse with the cell membrane and deliver the DNA into the cytoplasm
what is microinjection
DNA is injected into cell through micropipette but many cells must be injected before they successfully take up the DNA
what are the advantages and disadvantages of using viruses to genetically modify cells
+/ they are very good at getting the DNA into the nuclei as this is how they work naturally
-/ they can cause an immune response in some people
risky side effects
what is a knockout organism
an organism in which one or more genes are silenced so they no longer function
why are knockout organisms helpful
can be used to identify the function of a gene
can be used to investigate disease and potential treatments
what is a limitation of genetically modified bacteria
prokaryotic cells do not possess the biochemistry to produce more complex human proteins
what bacteria is used for the making of transgenic plants
bacterium Agrobacterium tumefaciens
(causes tumors in plants)
explain the steps in making transgenic plants
- Ti plasmid extracted from A.tumefaciens
- the gene which will be transferred to the plant is inserted and the Ti plasmid is returned to the bacteria
- the plant is infected with the modified bacterium and the engineered gene becomes part of the plant chromosome
- A.tumefaciens causes tumor to develop on the plant, these tumor cells can be taken and cultured to grow new transgenic plants
what are tumors in plants called
crown galls
how can genetic modification be used in farming to increase yield
disease resistant genes can be added to high-yield crops to maximize yield
are plant cells toti, multi or pluripotent
totipotent
explain flood-resistant rice
complete immersion in water usually destroys rice crops and with global warming increasing floods many crops were been destroyed so GM rice which can withstand total immersion in water for up to 3 weeks and still give 80% of yield
