DNA Profiling

Question 1

What is DNA profiling

Answer 1

Comparing the introns(non-coding regions) and exons(coding regions) within the DNA to identify individual

Question 2

What does polymorphic mean

Answer 2

What specific regions of DNA are called that vary highly between people, differences in these variable regions between people are known as polymorphisms

Question 3

What are short tandem repeats (STRs)

Answer 3

Regions of non-coding DNA that contain repeats of the same nucleotide sequence, the number of these repeats will change depending on the individual

Question 4

Stages in DNA profiling

Answer 4

-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 and visualised using gel electrophoresis

Question 5

Process of PCR

Answer 5

-individual segment of DNA extracted
-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 cycling through the dif temps the strands are separated and built up again

Question 6

What is a primer

Answer 6

Short section of DNA produced in a lab that is custom built to contain any sequence of nucleotides you desire(help DNA polymerase to know where to start copying on existing DNA)

Question 7

What is annealing

Answer 7

Primers and polymerase binding to DNA strand (cooler temp)

Question 8

What is denaturation

Answer 8

Heating DNA to break the hydrogen bonds between bases so strands separate

Question 9

Sources of DNA for genetic profiling

Answer 9

Tooth, bone, hair follicle, blood, saliva and semen

Question 10

What does gel electrophoresis separate fragments on

Answer 10

According to their size

Question 11

What cuts DNA into fragments

Answer 11

Restriction endonucleases, different endonucleases will cut the DNA at different base sequences

Question 12

How are the fragments visualised

Answer 12

Using southern blotting/UV gel

Question 13

Process of gel electrophoresis

Answer 13

-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