Dna finger prirting

1. DNA fingerprinting
(DNA指紋圖譜)
By Yu Zhi Heng
7B (30)

2. Historical background
 DNA fingerprinting was developed in 1984
 by Alec. J. Jeffrey at the University of
Leicester
 He was studying the gene of myoglobin.
This is a picture of Alec. J. Jeffrey

3. What is DNA Fingerprinting?
 The chemical structure of everyone's DNA is the
same.
 The only difference between people (or any
animal) is the order of the base pairs.
 The information contained in DNA is determined
primarily by the sequence of letters along the
zipper.
Structure of DNA

4. The different sequence
segments that vary
in size and
composition and
have no apparent
function are called
minisatellites
The different sequences is the same as the word "POST"
has a different meaning from "STOP" or "POTS," even
though they use the same letters. i

5.  Using these sequences, every person could be
identified solely by the sequence of their base
pairs
 there are so many millions of base pairs, the task
would be very time-consuming
 Instead, scientists are able to use a shorter
method, because of repeating patterns in
DNA.
 These patterns do not, however, give an individual
"fingerprint,"
 they are able to determine whether two DNA
samples are from the same person, related people,
or non-related people.

6. DNA Fingerprinting using
VNTR's
 On some human chromosomes, a short sequence
of DNA has been repeated a number of times.
 the repeat number may vary from one to thirty
repeats
 these repeat regions are usually bounded by
specific restriction enzyme sites
 cut out the segment of the chromosome
containing this variable number of tandem
repeats (VNTR's )
 identify the VNTR's for the DNA sequence of the
repeat.

7. Making DNA Fingerprints
 DNA fingerprinting is a laboratory
procedure that requires six steps:
 1: Isolation of DNA.
 2: Cutting, sizing, and sorting.
 Special enzymes called restriction enzymes
are used to cut the DNA at specific places

8.  3: Transfer of DNA to nylon.
The distribution of DNA pieces
 is transferred to a nylon sheet
 by placing the sheet on the gel
 and soaking them overnight.
 4-5: Probing.
Adding radioactive or colored probes to the
nylon sheet produces a pattern called the
DNA fingerprint.

9.  4-6: DNA fingerprint.
 The final DNA fingerprint is built by using
several probes (5-10 or more)
simultaneously.

10. Practical Applications of DNA
Fingerprinting
 1.Paternity and Maternity
 person inherits his or her VNTRs from his
or her parents
 Parent-child VNTR pattern analysis has
been used to solve standard father-identification
cases Can someone tell me who is my father?

11. 2. Criminal Identification and
Forensics
 DNA isolated from blood, hair, skin cells, or
other genetic evidence left at the scene of a crime
can be compared
 FBI and police labs around
the U.S. have begun to use
DNA fingerprints to link suspects
to biological evidence –
blood or semen stains, hair,
or items of clothing

12. 3. Personal Identification
 The notion of using DNA fingerprints as a sort of
genetic bar code to identify individuals has been
discussed
 4.Diagnosis of Inherited Disorders
 diagnose inherited disorders in both prenatal and
newborn babies
 These disorders may include cystic fibrosis,
hemophilia, Huntington's disease, familial
Alzheimer's, sickle cell anemia, thalassemia, and
many others.

13. 5.Developing Cures for
Inherited Disorders
 By studying the DNA fingerprints of relatives
who have a history of some particular disorder
 identify DNA patterns associated with the disease
 6.identification of Chinese medicine
 The Hong Kong Baptist University was able to
use DNA fingerprinting to identify the Chinese
medicine—Lingzhi in 2000

14. Considerations when evaluating
DNA evidence
 In the early days of the use of
genetic fingerprinting as criminal
evidence, given a match that had a
1 in 5 million probability of occurring
by chance the lawyer would argue
that this meant that in a country
of say 60 million people there were 12 people
who would also match the profile.

15. 2. Problems with Determining
Probability
 A. Population Genetics
 VNTRs, because they are results of genetic
inheritance
 it will vary depending on an individual's
genetic background

16. B. Technical Difficulties
 Errors in the hybridization and probing process
must also be figured into the probability
 Until recently, the standards for determining
DNA fingerprinting matches, and for laboratory
security and accuracy which would minimize
error

17.  When evaluating a DNA match, the
following questions should be asked:
-Could it be an accidental random match?
-If not, could the DNA sample have been
planted?
-If not, did the accused leave the DNA sample
at the exact time of the crime?
-If yes, does that mean that the accused is
guilty of the crime?

18. 
A Kid’s set of apparatus
for DNA fingerprinting,
What does it mean?
END