Unit8 Flashcards
What are DNA probes
Short single-stranded pieces of DNA that can be marked as fluorescent or radioactive
that can identify alleles of genes and screen patients-
this can be used finding out hereditary diseases.
probes are created to have complimentary base sequence to the allele to screen for
How do you DNA probes work
The patient the DNA sample is treated to make single-stranded
and them is mixed with the DNA probes
if the patient has the allele then the DNA probe will hybridise
and the label indicate the presence
DNA hybridisation Denaturation
the Patients DNA is heated to create a single strand
This is done by heated the Patients DNA - denatured as it breaks apart the hydrogen bonds
DNA hybridisation -annealing
The patient single-stranded DNA sample is mixed with the DNA probe and cooled to any complimentary sequences can align and form hydrogen bonds anneal
Some of the patient DNA samples will anneal back together but some will anneal to the DNA probe
Locating specific alleles of a gene
1 )
to locate the specific allele the DNA base sequence must be known to create the DNA probe
for example this can be used by determining DNA sequencing techniques
2) The fragment of DNA company produced using a gene machine
3)This fragment can be amplified using a PCR
4)The label has been added either radioactive or a fluorescent label which emits light under a UV light
What happens after hybridisation
DNA is washed so that any unbound DNA probes are washed away
Genetic screening
This method can be used to screen for potential genetic disorders or the presence of cancer-causing oncogenes
It is possible to scream for multiple diseases simultaneously using an array where multiple different DNA probes are attached
Personalised medicine
Is one key reason that having a DNA screen can be advantageous certain
drugs such as painkillers are more or less effective depending on your genotype it can also help determine the best dose which increases the effectiveness
Genetic councillung
Type of social work
People can have their family history researched to consider the likelihood of them carrying any alleles linked to disease
before started a family or for their general health patients are informed of any potential risks to them levels or future offspring if they are to carry this alleles
Three types of recombinant DNA tech
1) creating DNA fragments
2) genetic fingerprinting
3) genetic screening
How to amplify fragments
PCR
Amplifying dna fragments
Once the dna fragments have been isolated they need to be cloned to create large quantities this can be done vivo or vitro
IN vitro
Fragments of DNA can be amplified in vitro
via the plymerorase chain reaction DONR by an automated machines
PCR equipment list
Thermocyler
DNA fragments to be amplified
DNA polymerase
Taq pol.
Primers
DNA nucleotides 
PCR denaturing
Temperature is 95°
Breaks
Hydrogen bonds and split the DNA into single strand
PCR annealing
The temperature is then decrease to 55° so that the primers can attach
synthesis during PCR
The enzyme DNA polymerase then attaches complimentary free nucleotides and makes a new strand
align next to each template -synthesis
the temperature is increased to 72° for this stage the optimum for taq DNA polymerase
Advantages of
PCR
-Automated more efficient
-Rapid 100 billion copies of the union can be made within hours
-Doesn’t require living cells- Quicker and less complex Techniques needed
VNTR’s
95% of human DNA is made up from entrance which consist of many variable number tandem repeats
What is the probability of two individuals having the same VNTR
Very low however the more closely related you are the most similar VNTRs 
Genetic fingerprinting
Genetic fingerprinting is the analysis of the VNTR or DNA fragments and this can be used to determine genetic relationships in the genetic variability population
Genetic fingerprinting: collecting and extracting
Could be from blood body cells hair follicles if the DNA sample a small van PCR is used to amplify the amount of DNA
Genetic fingerprinting: digesting
Restriction endonucleases that Cut the DNA into smaller fragments
enzymes which cut close to the target l VNTR are added
Genetic fingerprinting: separation
Gel electrophoresis
The DNA samples and loaded into small wells in an agar
Gel
The gel is placed in a bigger liquid with an electrical voltage applied
DNA is negitivley charged so the DNA samples won’t move through the gel toward the positive end of the gel 
