gene technologies 3.8 Flashcards
(20 cards)
what is meant by recombinant DNA technology
the transfer of DNA fragments from one organism to another
why does recombinant DNA technology work
genetic code is universal
transcription and translation occur by the same mechanism
result in the same amino acid sequence across organisms
summarise the process of using reverse transcriptase to produce DNA fragments
mRNA complementary to the target gene used as a template
free nucleotides added
match up to their complementary base pairs
reverse transcriptase forms sugar phosphate backbone
produces complementary DNA
summarise the process of using enzymes to produce DNA fragments
restriction endonucleases cut DNA at specific sequences
different REs cut at different points
same RE will always cut at the same sequence
using specific REs allows you to cut out a certain gene of interest
2 ways to amplify DNA fragments
in vitro - PCR
in vivo - host cells
describe the reaction mixture in the first stage of PCR
DNA fragment
complimentary primers
free nucleotides
DNA polymerase
summarise process of amplifying DNA fragments using PCR
heated to separate the DNA strands
cooled to allow primers to bind
heated to activate DNA polymerase and allow free nucleotides to join
new DNA acts as a template for next cycle
summarise the process of inserting a DNA fragment into a vector
a plasmid used as vector
cut using same restriction enzymes as the DNA
so that ends are complimentary
DNA ligase joins the fragment and plasmid together
summarise the process of inserting a vector into a host cell
cell transformation
host cells mixed with vectors in ice-cold solution
heat shocked to encourage cells to take up vectors
cells grown
DNA fragment cloned
summarise the process of identifying transformed cells
marker genes inserted into vectors along with DNA
UV light used to identify which cells have taken up the vector and which haven’t
how can DNA probes be used to locate specific alleles
probe sequence complementary to target allele
probe is labelled
amplified using PCR
added to sample of single stranded DNA
probe will bind if allele is present
3 applications of DNA probes
screen for heritable health condition
identify a gene for use in genetic engineering
predict how someone will respond to a drug
what is the purpose of DNA hybridisation
measure the degree of difference between two strands of DNA
compare someones DNA to a certain gene to see if they have it
summarise the process of DNA hybridisation
one DNA strand labelled
mixed with unlabelled comparison strand
the more similar the strand the more strongly they will bind
more energy will be required to break strands apart
what are the benefits of genetic profiling
can identify heritable diseases very early
treat before symptoms develop
reduces impact on individual
treatment can be personalised to make it more effective
what is genetic fingerprinting
a technique used to compare two DNA samples and determine whether they came from the same individual
how does genetic fingerprinting work
every organisms genome contains non-coding regions
called variable number tandem repeats
probability of 2 individuals having same VNTRs is very low
we can compare these areas to see if 2 DNA samples came from the same person
summarise the process of genetic fingerprinting analysis
DNA sample obtained
VNTRs cut out using restriction enzymes
labelled
cloned using PCR
fragments separated using gel electrophoresis
banding patterns of each sample compared
how does gel electrophoresis work
DNA fragments are placed at one end of gel
electric current applied
causes DNA fragments to move towards other end of gel (negatively charged phosphate)
shorter fragments travel further
pattern of bands created is unique to each individual
3 applications of genetic fingerprinting
forensics
medical diagnosis
animal and plant breeding
