Genetic Modification Flashcards
what is genetic engineering
involves transferring genes from one organism to another
what are transgenic organisms
organisms which have received genes from another species
what are vectors used for
carrying the DNA from one section to another
what is one example of when genetic engineering has been used to treat humans
type 1 diabetes - insulin
what do restriction enzymes do
cut DNA at specific sites
what do ligase enzymes do
join pieces of DNA together
how do restriction enzymes work
they isolate the required gene and leave it with sticky ends (a short section of unpaired bases)
eg the same enzyme then cut a bacterial plasmid and leave it with the same sticky ends
how do ligases work
if two pieces of DNA have matching sticky ends ligase will link them to form a single unbroken molecule of DNA
what two things can act as vectors for genetic engineering
- plasmids
- viruses
how do plasmids and viruses act as vectors for genetic engineering
they take up pieces of DNA then insert this recombinant DNA into other cells
what is recombinant DNA
DNA of two different organisms combined as a result of gene transfer
for what organisms would you use viruses as the vector for genetic engineering
humans or bacteria
for what organisms would you use plasmids as the vector for genetic engineering
for bacteria or yeast
what is used to join two separate pieces of DNA together
DNA ligase
how does genetic engineering quickly spread
for example insulin
how can insulin be produced
the gene for human insulin can be inserted into bacteria which then produce the human insulin, which can be collected and purified for medical use to treat diabetes
what are the steps of genetic modification of bacteria to produce human insulin
- the gene for insulin production is located within the chromosome
- restriction enzymes are used to isolate (cut out) the gene, leaving it with sticky ends (short sections of unpaired bases)
- a bacterial plasmid is cut by the same restriction enzyme to leave it with corresponding sticky ends
- the plasmid and human gene are joined together by DNA ligase enzyme
- the genetically engineered plasmid is inserted into the cell
- when the bacterial cell reproduces, the plasmids are copied as well so they can be quickly spread until they all contain the human insulin gene and make human insulin
what is a plasmid
a circle of dna inside bacterial cells
how can large quantities of insulin be made
put the bacterial cells into a fermenter to control conditions and make them reproduce quickly
why are bacteria useful for genetic engineering purposes
- they contain the same genetic code as the organisms we take the genes from so they can easily read it and produce the same proteins
- there are no ethical concerns over their manipulation and growth (unlike animals)
- the plasmids in the bacterial cell separate from the main bacterial chromosome making them easy to remove and manipulate and replace
what are genetically modified plants (GM crops - genetically modified crops)
plants that have had foreign DNA inserted into their genome
in what ways have some crops been genetically modified already
- to contain a gene from a bacterium that produces a poison that kills insects
- to make them resistant to herbicides
- to produce additional vitamins and improved nutritional value (eg golden rice which contains genes from another plant which make the grain produce a chemical that is turned into vitamin A in the human body)
- to be drought resistant (grow better in dry conditions)
advantages of GM crops
- reduced use of chemicals such as herbicides so therefore better for the environment, cheaper and less time consuming for the farmers
- increased yields from the crops as they are not competing with anything
what are the disadvantages of GM crops
- increased cost of seeds to cover the cost of developing them = poorer/smaller farms at a disadvantage
- increased dependency on the certain chemicals that the crops are resistant to
- risk of inserted gene being transferred to wild plants by pollination (they could gain the herbicide resistant gene)
- reduced biodiversity
- some researchers say that plants that have had genes inserted into them do not grow as well
what is rDNA
recombinant DNA
