DNA fragments Flashcards
(30 cards)
what is meant by recombinant DNA technology ?
- the combining of different organisms DNA
what does recombinant DNA technology allow scientists to do ?
- allows scientists to manipulate and alter genes to improve industrial processes and medical treatment
what is the first step of recombinant DNA technology ?
- to produce or isolate the fragments of DNA to be recombined with another piece of DNA
what are the 3 methods to create DNA fragments ?
- using enzyme reverse tanscriptase to peform reverse transcription
- using restriction endonucleases to cut up DNA
- using a gene machine
function of reverse transcriptase ?
- ## reverse transcriptase can make DNA copied from mRNA
where is reverse transcriptase found ?
- it naturally occurs in viruses such as HIV
process of reverse transcription?
- a cell that naturally produces the protein of interest is selected
- these cells should have large amounts of mRNA for that protein
- extract the mRNA
- reverse transcriptase enzymes will join the DNA nucleotides with complimentary bases to the mRNA sequence
- single stranded DNA is made
what is the single stranded DNA made by reverse transcriptase called ?
- cDNA
- complimentary DNA
how do you make the DNA fragment produced by reverse transcriptase double stranded ?
- you would use DNA polymerase to join together nucleotides to make a second chain
what is the main advantage of reverse transcription ?
- the cDNA produced contain only the coding regions of DNA
- only exons, no introns
- because it is based on a mature mRNA template
why is cDNA not containing introns an advantage ?
- because of scientists work with prokaryotes
- they dont have the ability to remove introns from the pre mature mRNA
what are restriction endonucleases ?
- enzymes which cut up DNA
where are restriction endonucleases found ?
- these naturally occur in bacteria as a defence mechanism
what do the many restriction enzymes have in terms of shape ?
- they have an active site complementary in shape to a range of different DNA base sequences
what is the base sequence called that the restriction enzymes are complimentary to ?
recognition sequences
therefore what do the restriction enzymes specifically do ?
- each enzyme cuts the DNA at specific locations
what are the specific locations that restriction enzymes cut called ?
recognition sites
what are the 2 ways that restriction endonucleases cut the DNA
- some enzymes cut the DNA at the same location in the double strand
- and create a blunt end
- other enzymes cut at palindromic sequences to create staggered ends and and exposed DNA bases
what are the staggered ends called ?
- palindromic ends
- sticky ends
why are the staggered ends called sticky ends ?
- because they have the ability to join to DNA with complimentary base pairs
what is meant by palindromic sequences ?
bases that are antiparallel to eachother
what is meant by a gene machine?
- DNA fragments can be created in a lab using a computerised machine
what would the scientists have to do before the gene machine process ?
- they would examine the protein of interest to identify the amino acid sequence
- and from that work out hat the mRNA and DNA sequence would be
what occurs after the scientists identify the mRNA and DNA sequence ?
- the DNA sequence is entered into the computer
