DNA Profiling Flashcards
What is DNA profiling
Comparing the introns(non-coding regions) and exons(coding regions) within the DNA to identify individual
What does polymorphic mean
What specific regions of DNA are called that vary highly between people, differences in these variable regions between people are known as polymorphisms
What are short tandem repeats (STRs)
Regions of non-coding DNA that contain repeats of the same nucleotide sequence, the number of these repeats will change depending on the individual
Stages in DNA profiling
-DNA sample extracted
-DNA amplified using PCR(polymerase chain reaction)
-cut DNA fragments, fragments of different lengths are produced by cutting up the DNA
-the fragments are separated using gel electrophoresis and visualised using fluorescent gel and UV light
Process of PCR
-individual segment of DNA extracted and added to DNA nucleotides, DNA polymerase and primers in thermocycler
-by raising the temperature to about 90C the strands are separated
-the temp is lowered to 55C and synthetic DNA fragments are added which bind to the strands at correct positions
-temp raised to about 70C and the enzyme DNA polymerase which is added builds up two new complete copies of the DNA strands by forming phosphodiester bonds between adjacent nucleotides
-by cycling through the dif temps the strands are separated and built up again, many copies produced by producing complementary strands
What is a primer and it’s role
Have a specific base sequence which binds to complementary bases at either end of the DNA to be amplified therefore providing a site for the DNA polymerase to bind and create a complementary strand
What is annealing
Primers and polymerase binding to DNA strand (cooler temp)
What is denaturation
Heating DNA to break the hydrogen bonds between bases so strands separate
Sources of DNA for genetic profiling
Tooth, bone, hair follicle, blood, saliva and semen
What does gel electrophoresis separate fragments on
According to their size
What cuts DNA into fragments
Restriction endonucleases, different endonucleases will cut the DNA at different base sequences
How are the fragments visualised
Using fluorescent gel and UV light
Process of gel electrophoresis
-fragments of DNA added to the wells of an agarose gel
-current passed through the gel and DNA (negatively charged) moves from negative to positive end through the gel
-smaller fragments travel faster so will move further down the gel in the same amount of time
-southern blotting makes the banding visible
How would scientists share results
Scientific article/ scientific conferences/ media reports eg TV
How to study proteins
Using proteomics
