Manipulating Genomes : Genetic Engineering Flashcards
Genetic engineering and what makes this possible?
Manipulation of the DNA sequences of an organism
- genetic code is UNIVERSAL - nearly all use same 4 bases + same codon code for same amino acids in all living things
What is recombinant DNA , transgenic organism, and genetically modified organisms?
RECOMBINANT DNA: altered DNA, with the introduced nucleotides
TRANSGENIC ORGANISM: organism that contains nucleotide sequences from different species
GENETICALLY MODIFIED ORGANISM (GMO): any organism that has introduced genetic material
Uses of genetic engineering?
Genetic modification of crops - increase YIELDS
- resistance to drought,disease,pesticide and herbicides /provide increased nutritional value
Genetic modification of livestock - disease/pest resistance and increased productivity
Genetic modification of bacteria - produce medicines (insulin ), decompose toxic pollutants, carry out large scale chemical production
Method of genetic engineering?
- Identify DNA fragment/gene
- Isolation of the desired DNA fragment (either using restriction enzymes, a gene machine or reverse transcriptase)
- Multiplication of the DNA fragment (using PCR)
- Transfer into the organism using a vector (e.g. plasmids, viruses, liposomes). Electroporation is used to encourage uptake of plasmid vectors.
- Identification of the cells with the new DNA fragment (by using a marker), which is then cloned
Enzymes used in genetic engineering techniques?
RESTRICTION ENDONUCLEASES: cut genes at specific base sequences (restriction sites). Different restriction enzymes cut at different restriction site
LIGASE - joins together the cut ends of DNA by forming phosphodiester bonds
REVERSE TRANSCRIPTASE - Used to build double stranded DNA from single stranded RNA
What are vectors and the 3 types/
Vectors - used to deliver DNA fragments into a cell
PLASMIDS: transfer DNA into bacteria/yeast
VIRUSES : transfer DNA into human cells/bacteria
LIPOSOMES : fuse will cell membranes to transfer DNA into cells
What are markers and the 3 types?
Markers - genes that code for identifiable substances that can be tracked
Fluorescent markers e.g. green fluorescent protein (GFP) which fluoresces under UV light
Enzyme markers e.g. β-glucuronidase (GUS) enzyme which transforms colourless or non-fluorescent substrates into products that are coloured or fluorescent
Antibiotic resistance marker genes - required gene sequence is inserted into gene for antibiotic resistance - inactivates the antibiotic resistance gene and therefore means that successfully transformed bacteria will be wiped out if exposed to the antibiotic.
A replica plating method is then used to isolate the successfully transformed bacteria
Uses of genetic engineering?
GM microorganisms: make recombinant proteins - research/treatment (cancer,diabetes)
GM plants/animals - meet global food demands/produce protein for meds
GM Crops - resistance to herbicides/pests/enriched in vitamins
- reduce impact of farming on environment due to less need for pesticides
GM livestock
GM salmon
GM pathogens
Advantages of genetic engineering microorganisms to produce recombinant human proteins ?
- cost effective to produce large volumes
- simpler
- faster to produce many proteins
- reliable supply
- proteins are engineered to be identical to human proteins or have beneficial modifications
- can solve the issue for people who have moral or ethical or religious concerns against using cow or pork produced proteins
Why are recombinant human proteins produced using eurkaryotic cells?
These cells carry out POST TRANSLATIONAL MODIFICATION (due to presence of Golgi apparatus/enzymes) - needed to produce suitable human protein
benefits of using genetic engineering rather than selective breeding techniques to solve the global demand for food?
Organisms with the desired characteristics are produced more quickly
All organisms will contain the desired characteristic (there is no chance that recessive allele may arise in the population)
The desired characteristic may come from a different species/kingdom
How is livestock modified?
- Pharming - produce pharmaceutical drugs
- biopharm sheep/goats genetically modified to produce many useful human proteins imm their milk
How are GM salmon (AquaAdventure salmon) genetically modified ?
- genetically modified to GROW RAPIDLY due to growth hormone being produced throughout year, instead of just spring/summer
- has a product to sell in half the time —> INCREASED YIELD
- combined growth hormone gene from chinook salmon with promoter gene from ocean pout —> ensures gene is continually expressed
- alls salmon are female/sterile - prevent reproducing in wild
How are pathogens genetically modified ?
- modified to shed light on their metabolism, drug resistance / how it causes damage to its host
- development of effective vaccines and drugs can be aided by this research
Adenoviruses can be genetically altered to act as vectors in gene therapy - ideal vectors as they are not cell-specific or species-specific - infect cells of many mammals
Specific genes are removed from the virus so that it can not replicate inside host cells, creating space for the insertion of other desired genes
How is human insulin produced?
- Bacteria plasmids modified to include HUMAN INSULIN GENE
- Restriction endonucleases used to cut open plasmids/ DNA ligase is used to splice the plasmid and human DNA together
- recombinant plasmids are then inserted into Escherichia coli by transformation (bath of calcium ions and then heat or electric shock)
- the transgenic bacteria are identified (by the markers), they are isolated, purified and placed into fermenters that provide optimal conditions
- The transgenic bacteria multiply by binary fission, and express the human protein - insulin, which is eventually extracted and purified
