DNA profiling

Question 1

what is a DNA probe and examples of when it might be used to locate specific sequences of DNA

Answer 1

-short single stranded length of DNA, complimentary to specific DNA being investigated
-can be labelled= radioactive marker or fluorescent marker emits colour on exposure to UV light

Question 2

what is a microrray

Answer 2

fixed surface with number of different DNA probes attached

Question 3

what are examples of sources of DNA for DNA profiling

Answer 3

-mouth swab, blood, hair, saliva, skin cells, bone

Question 4

what is the procedure for DNA profiling

Answer 4

1. obtain DNA, extracted from sample and if only small quantity can be amplified using PCR
2. digestion= restriction enzymes cut DNA into fragments, cut DNA at specific recognition sites, fragments will vary in size from person to person
3. separation= DNA fragments are separated by gel electrophoresis and stained
4. a banding pattern can be seen
   5.DNA to which the individual is being compared is treated with same restriction enzyme and is subject to electrophoresis= pattern compared
5. can be transferred to membrane and x-ray for DNA fingerprint

Question 5

what type of DNA is analysed in DNA profiling

Answer 5

-short tandem repeats (STRs)= highly variable short repeating lengths of DNA= exact number of STRs varies from person to person
-can be stored for many years

Question 6

what are the applications of DNA profiling

Answer 6

-forensic science= matching DNA found in crime scene to suspect
-paternity testing
-analysis of disease= protein electrophoresis to detect type of haemoglobin to diagnose sickle cell anaemia,
=identifying number of repeat sequences within gene allele for conditions such as huntingdon disease

Question 7

Describe how the technique of genetic fingerprinting is carried out and explain how it can be used to identify a person, such as Saddam Hussein

Answer 7

1. DNA is cut;
2. using restriction enzyme;
3. electrophoresis;
4. separates according to length/mass/size;
5. DNA made single-stranded;
6. transfer to membrane/ Southern blotting;
7. apply probe;
8. radioactive/ single stranded/ detected on film/ fluorescent;
9. reference to tandem repeats/VNTRs/minisatellites;
10. pattern unique to every individual;