B6.2 Feeding the Human Race 2 Flashcards
Genetic engineering
When scientists alter an organism’s genome to produce an organism with desired characteristics
- v. Accurate as single genes can be targeted, occurs in 1 generation
How have scientists genetically engineered cotton?
Increase crop yield from same area of land
How have scientists genetically engineered corn?
To produce toxins that kill insects, making plant resistant to pests so smaller amounts of pesticides needed
How have scientists genetically engineered bacteria?
To produce medical drugs like insulin/drugs to treat diseases domesticated in animals
Risks of genetic engineering
- eating genetically engineered organisms may lead to health problems (eg. new allergen)
- genetically engineered crops may cross pollinate with wild plants, introducing new gene to wild plants, disrupting balance of ecosystem
- unethical? Science interfering with nature
- new and no one is sure of long term effects
Basic steps to genetic engineering
- Identify genes coding for the desired characteristic
- Remove gene from donor host
- Insert gene into host organism (often bacterium)
Restriction enzymes
They cut donor DNA at specific base sequences, either side of desired gene
Same restriction enzymes used to cut open bacterial plasmid
Sticky ends
restriction enzymes make staggered cut, leaving a few exposed, unpaired bases on ends of DNA attached
Ligase enzymes
Used to rejoin DNA at the sticky ends as both host + donor have the same sticky ends = new gene joined to plasmid DNA
Differences between cloning and genetic engineering
Cloning - produces exact copier
Genetic engineering - produces a unique set of genes
Cloning- genes copied within the same species
Genetic engineering- genes transferred between species
First steps to genetically engineering bacteria to produce insulin
- insulin gene is removed from human DNA. Gene is cut from rest of DNA by restriction enzymes
- loop of bacterial DNA called plasmid is removed from the bacterial cell
Second steps to genetically engineering bacteria to produce insulin
-the loop of DNA is cut ope using the same restriction enzymes that were used to cut the insulin gene from the human DNA
Third steps to genetically engineering bacteria to produce insulin
-human insulin gene and loop of DNA are mixed, the human gene becomes inserted between the cut ends of the loop of DNA. Cut surfaces are repaired using the enzyme DNA ligase
Fourth steps to genetically engineering bacteria to produce insulin
Repaired loop of DNA now carrying the human gene is then inserted into a new bacterium. The plasmid is called a vector- it carried the human gene
Fifth steps to genetically engineering bacteria to produce insulin
The bacteria are now called transgenic bacteria because they have DNA from another organism. They are grown in large numbers to produce the insulin for us
How to check that the gene had successfully transferred into the host’s genome
- insert an antibiotic resistance gene into the plasmid at the same time as inserting the gene coding for the desired characteristic
- transfer bacteria to an agar plate containing the selected antibiotic. Incubate and allow time for bacteria to grow
- any bacterial colonies present will survive because they now contain the antibiotic resistance marker gene as well as the desired gene
What happens to transgenic bacteria?
They are then placed into fermenter units which provide optimum conditions for bacterial growth. Bacteria replicate and are killed by the heat, leaving behind insulin
Biotechnology
The use of biological processes or living organisms to manufacture products
(Eg. Genetically modified organisms)
Genetically modified
(gam) = genetically engineered but in reference to plants c animals
Golden rice
(GM) created when a gene is taken from a daffodil and placed into rice —> rice produced beta-carotene which body uses to make vitamin A
Bt corn
(g
GM) produced by inserting a gene into maize from the bacterium ‘Bacillus thuringiensis’ —> gene codes for a protein that is poisonous to insect pests, corn produces poison, kills pets trying to eat it
Extra step in genetically modifying plants/animals
INSERTION = Useful gene is spliced into carrier DNA, combined DNA is placed in a virus, virus injected into plant cell
(Plasmids, bacteria and viruses can all be used as vectors to transfer foreign DNA into an organism)
