Genetic engineering Flashcards
What is genetic engineering?
manipulation of an organism’s genome to achieve a desired outcome
What is recombinant DNA?
DNA formed from joining together DNA from different sources
What is the role of restriction endonucleases?
cut the required gene from the DNA of an organism
What are sticky ends?
small regions where the restriction endonuclease has cut the DNA leaving exposed bases
Apart from cutting the gene from the DNA, how else can you obtain the required gene?
isolating the mRNA for the desired gene, then using reverse transcriptase to produce a single stranded complementary DNA strand.
What is the advantage of using mRNA to get the gene over cutting DNA?
it’s easier to identify the desired gene as a particular cell will make very specific types of mRNA
What is a recognition sequence?
sequence of bases recognised by restriction endonucleases causing it to cut the DNA at that point
What is a vector and what is the most commonly used vector?
a vector transfers the DNA into a cell, usually a plasmid
How is the desired gene bonded to the vector’s DNA?
Desired gene is inserted into vector, and same restriction endonuclease is used to cut vector DNA at same recognition sequence creating complementary sticky ends to the gene. DNA ligase is added which forms phosphodiester bonds joining the desired gene to the vector DNA
Why are vectors beneficial to this process?
they can be genetically engineered to contain a marker gene giving the bacteria antibiotic resistance so you can tell if the bacteria have taken up the vector containing the desired gene
What can the role of a second marker gene in the plasmid be for?
second marker gene can be where the restriction endonuclease cuts the vector’s DNA so if the DNA fragment is inserted successfully, this marker gene will not function, allowing scientists to identify plasmids successfully containing the gene
How is the plasmid with the desired gene transferred into the host cell?
culture bacterial cells and plasmids in calcium rich solution and raise temperature, bacterial membrane is more permeable and plasmid enters.
What is electroporation?
a small electrical current is applied to the bacteria, this makes membranes very porous and so plasmids move into the cell
