2 Historical background DNA fingerprinting was developed in 1984by Alec. J. Jeffrey at the University of LeicesterHe 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 KEY CONCEPT DNA fingerprints identify people at the molecular level.
5 A DNA fingerprint is a type of restriction map. DNA fingerprints are based on parts of an individual’s DNA that can by used for identification.based on noncoding regions of DNAnoncoding regions have repeating DNA sequencesnumber of repeats differs between peoplebanding pattern on a gel is a DNA fingerprint
6 DNA fingerprinting is used for identification. DNA fingerprinting depends on the probability of a match.Many people have the same number of repeats in a certain region of DNA.The probability that two people share identical numbers of repeats in several locations is very small.(mother) (child 1) (child 2) (father)
7 Several regions of DNA are used to make DNA fingerprints. Individual probabilities are multiplied to find the overall probability of two DNA fingerprints randomly matching.,400,0001 chance in 5.4 million peoplex=Several regions of DNA are used to make DNA fingerprints.
8 DNA fingerprinting is used in several ways. evidence in criminal casespaternity testsimmigration requestsstudying biodiversitytracking genetically modified crops
9 The different sequence segments that vary in size and composition and have no apparent function are called minisatellitesThe 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
10 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-consumingInstead, 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.
11 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 repeatsthese repeat regions are usually bounded by specific restriction enzyme sitescut 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.
12 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
13 3: Transfer of DNA to nylon. The distribution of DNA pieces is transferred to a nylon sheetby placing the sheet on the geland soaking them overnight.4-5: Probing. Adding radioactive or colored probes to the nylon sheet produces a pattern called the DNA fingerprint.
14 4-6: DNA fingerprint.The final DNA fingerprint is built by using several probes (5-10 or more) simultaneously.
15 Practical Applications of DNA Fingerprinting 1.Paternity and Maternity : person inherits his or her VNTRs from his or her parentsParent-child VNTR pattern analysis has been used to solve standard father-identification casesCan someone tell me who is my father?
16 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 comparedFBI and police labs aroundthe U.S. have begun to useDNA fingerprints to link suspectsto biological evidence –blood or semen stains, hair,or items of clothing
17 3. Personal Identification The notion of using DNA fingerprints as a sort of genetic bar code to identify individuals has been discussed4.Diagnosis of Inherited Disordersdiagnose inherited disorders in both prenatal and newborn babiesThese disorders may include cystic fibrosis, hemophilia, Huntington's disease, familial Alzheimer's, sickle cell anemia, thalassemia, and many others.
18 5.Developing Cures for Inherited Disorders By studying the DNA fingerprints of relatives who have a history of some particular disorderidentify DNA patterns associated with the disease6.identification of Chinese medicineThe Hong Kong Baptist University was able to use DNA fingerprinting to identify the Chinese medicine—Lingzhi in 2000
19 Considerations when evaluating DNA evidence In the early days of the use ofgenetic fingerprinting as criminalevidence, given a match that had a1 in 5 million probability of occurringby chance the lawyer would arguethat this meant that in a countryof say 60 million people there were 12 peoplewho would also match the profile.
20 2. Problems with Determining Probability A. Population GeneticsVNTRs, because they are results of genetic inheritanceit will vary depending on an individual's genetic background
21 B. Technical Difficulties Errors in the hybridization and probing process must also be figured into the probabilityUntil recently, the standards for determining DNA fingerprinting matches, and for laboratory security and accuracy which would minimize error
22 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?
23 A Kid’s set of apparatus for DNA fingerprinting, What does it mean? END