DNA profiling

Question 1

process in making a DNA profile

Answer 1

1. obtain a tissue sample and extract DNA
2. DNA is cut/ goes through a PCR to form different sized fragments
3. fragments are separated then visualised
4. DNA profile compared to a reference profile

Question 2

how is the tissue obtained for a sample

Answer 2

cells are from:
cheek swab
bond marrow
white blood cells
blood

Question 3

what methods can be used to remove the DNA from the tissue

Answer 3

treat cells with detergent to disrupt cell membrane and release DNA
proteases are added to inactivate enzymes which could destroy the DNA
cold ethanol is then added to precipitate out DNA
DNA will need to be amplified if there is a very small sample (PCR)

Question 4

why are restriction enzymes used in the DNA profiling procedure

Answer 4

to cut and form different sized fragments

Question 5

how do restriction enzymes identify where to cut DNA

Answer 5

enzymes only cut at specific base sequences called restriction sites in STR sequence to form fragments

Question 6

what is the technique to copy STR sequences in DNA profiling

Answer 6

polymerase chain reaction (PCR)

Question 7

what technique is used to separate the STR sequence fragments

Answer 7

gel electrophoresis

Question 8

how is a conclusion reached from a DNA profile

Answer 8

each STR band will show up as a band on the gel
compare thickness of bands to reference
compare position of the bands to reference

Question 9

why is DNA profiling sometimes wrong

Answer 9

cross contamination can occur since it is a multistep process
only certain DNA regions looked at not entire sequence
chance of identical profile with someone else

Question 10

what does STR stand for

Answer 10

short tandem repeats

Question 11

where are STR sequences found

Answer 11

within introns

Question 12

features of the location of STR sequences

Answer 12

same location on all chromosomes but the number of repeats at each loci on the chromosomes are different