21.4 Genetic engineering Flashcards
what is genetic engineering?
the manipulation of the genome
basic outline of genetic engineering
desirable gene is isolated and then placed in another organism using a suitanle vector
what is an organism which carries a gene from another organism called?
transgenic
a genetically modified organism
what enzymes are used for isolating the desired gene?
restriction endonucleases
what is a sticky end?
a few bases left behind when the restriction endonucleases cuts the desired gene out
why are sticky ends useful?
makes it easier to insert a desired gene into the DNA of another organism
what are the two techniques for isolating a gene?
use of restriction endonucleases
use of reverse transcriptase
how is reverse transcriptase used to remove a desired gene?
used to produce a single strand of complimentary DNA from mRNA
why is the use of reverse transcriptase an advantage?
it makes it easier to identify the desired gene as the mRNA produced will be very different to the desired gene isolated by reverse transcriptase
what is the isolated DNA inserted into to be able to reach a host cell?
a vector
what is the most common vector used in genetic engineering?
bacterial plasmids
why are bacterial plasmids the preffered vector?
they are small
they can replicate independently
what is recombiant DNA?
when the plasmid goes into a new host cell and combines with the host’s DNA
what do plasmids used for vectors contain?
marker genes
what is an example of a marker gene?
one which gives antibiotic resistance
the bacteria is grown in a media containing antibiotic
checks that the bacteria has taken up the plasmid
what is used to cut open the plasmid?
the same restriction endonuclease used to isolate the desired gene
why is it important that the plasmid is cut using the same restriction endonuclease?
it ensures that the sticky ends formed in the plasmid are complimentary to the bases in the desired gene
how is the desired gene connected to the rest of the DNA in a plasmid?
DNA ligase forms phosphodiester bonds between the sugar and phosphate groups which joins the strands together
what is the second gene marker in a plasmid used for?
to show whether a plasmid contains the recombinant gene
how does the second gene marker activated?
if the DNA marker is inserted then the marker gene does not function
what is transformation?
the process of transferring the plasmid containing the recombinant DNA into the host cell
what are the methods of transformation?
- permeable membranes
- electroporation
how are permeable membranes used for transformation?
the plasmid is placed in a calcium rich medium and high temperature in which the bacterial membrane to become more permeable to allow plasmids to enter
what is electroporation?
when a small electric current is applied to the bacteria and the membrane becomes more porous to allow the plasmid to enter the cell
why is electroporation less useful in whole organisms?
the electric current can cause the membrane to become damaged and destroys the cell
what is electrofusion?
when a tiny electric is applied to the membranes of two cells which causes the cells to fuse and form a hybrid cell
what does the hybrid cell formed from electrofusion contain?
the DNA from both fused cells
why is electrofusion difficult in animal cells?
they are more difficult to fuse
how is electrofusion used to produce monoclonal antibodies?
when a tumour cell is fused with an antibody
forms a hybridoma
allows it to rapidly divide
what is a transformed cell?
a cell which has taken up a vector containing the desired gene
what are prokaryotes used in genetic engineering for?
bacteria have been genetically modified to produce:
- insulin
- clotting factors
- antibiotics
- vaccines
how are plants genetically modified?
a desired gene is placed in a plasmid with a marker gene
then carried to the plant cell DNA
callus forms which can each grow into a new plant
diagram for genetic engineering in plasmid
diagram for genetic engineering with a plant
