Gene Technology Flashcards
what is the name of the enzyme that is used to cut sections of DNA?
-restriction endonuclease
how does restriction endonuclease cut sections of DNA?
-through a hydrolysis reaction at specific sequences of bases called recognition sequences
what are the two cuts that restriction enzymes can make?
-blunt cut where it is cut straight across two bases
-sticky ends where the cut is staggered
what are sticky ends?
-short sections of DNA where a small number of bases are exposed and unpaired
what is the job of reverse transcriptase?
-used to make a desired section of DNA from the genes mRNA
what are the steps of reverse transcriptase changing mRNA into DNA?
-mRNA is isolated and extracted in a cell in which the desired gene is very active
-reverse transcriptase uses the mRNA as a template strand to form a strand of cDNA
-DNA polymerase then is used to make the cDNA double stranded
what is the job of DNA probes?
-used to identify sections of DNA that contain a specific sequence of bases
what are DNA probes made up of ?
-a probe is a short section of DNA
-and they are labelled with either a radioactive or a fluorescent tag
how do probes attach to a strand of DNA?
-because they are a short section of DNA, this will be complementary to a specific sequence of bases
-so the strand will hybridise with the DNA strand
what are the two types of tags on a probe and how are they detected?
-radioactive = x-ray
-fluorescent = UV light
how is the DNA prepared before attaching a probe? what happens after the probe is attached?
-DNA that is expected to contain the sequence is hydrolysed by adding restriction endonuclease
-the DNA fragments are then separated by gel electrophoresis
-the DNA is then transferred to a nylon membrane
-probe is added and if the sequence us present the probe will hybridise and if not the probe will be washed off
