Unit 7- Using DNA Flashcards
What is a vector?
A length of DNA that carries the gene we want in a host cell
Why can’t we just insert a strand of DNA into a cell?
As its not incorporated into the cells genome the DNA will just get broken down
Shape and size of a plasmid
About 5 genes long and circular
What functions do vectors have?
- small but big enough to hold another gene
- closed loop so less likely to be broken down
- contains promoters so the gene gets replicated and expressed
- it contains marker genes so cells containing the vector can be seen
How is a gene inserted into a plasmid?
1- cut the desired gene from donor DNA using restriction endonucleases (sticky ends are needed)
2- use the same RE to cut the plasmid in the middle of a marker gene
3- mix the gene and plasmids in a test tube, as they were cut by the same RE they should have the same sticky ends and anneal by complementary base pairing
4- DNA ligase reforms the phosphodiester bonds to complete the hybrid vector
How can we insert modified DNA into bacteria?
Heat shock
Electroporation
How can we insert modified DNA into plant cells?
Gene gun
Plant infection
How can we insert modified DNA into humans and animals?
- micro injection
- liposomes
- viruses
What is heat shock?
Making the cell membrane permeable enough to insert the modified DNA by suddenly heating the cell
What is electroporation?
Temporarily disrupting the cell membrane using a high voltage pulse, so the membrane is permeable enough to let the plasmid in
How is DNA inserted via gene gun?
Firing a tiny gold particles coated in the modified DNA, using an air gun, plant cell walls are tough so this penetrates them
How is modified DNA inserted into a plant cell via plant infection?
Inserting a new gene into the plasmid of the bacteria that infects most species
Then exposing the pathogen to the plant
How is modified DNA inserted into animal cells via micro injection?
DNA is inserted directly into nucleus using a fine micro pipette
How is modified DNA inserted into an animal cell via liposomes?
Cells in vivo can fuse with liposomes which encase the DNA, hence inserting the DNA by endocytosis
How is modified DNA inserted into a human cell via a virus?
Viruses can be genetically modified to deliver the DNA instead of harmful virus DNA