Do you want to create an amazing science fair project on DNA fingerprinting ? You are in the right place. Read the below given article to get a complete idea on DNA fingerprinting: 1. Introduction to DNA Fingerprinting 2. Meaning of DNA Fingerprinting 3. Principles 4. Mechanism 5. Applications.

Contents:

  1. Science Fair Project on Introduction to DNA Fingerprinting
  2. Science Fair Project on the Meaning of DNA Fingerprinting
  3. Science Fair Project on the Principle Involved in DNA Fingerprinting
  4. Science Fair Project on the Mechanism of DNA Fingerprinting
  5. Science Fair Project on the Applications of DNA Fingerprinting

Science Fair Project # 1. Introduction to DNA Fingerprinting:

Every individual organism is unique. Each person has a unique DNA fingerprint. A DNA fingerprint of a person is the same for every cell, tissue and organ.

DNA fingerprint cannot be altered by any known treatment. The ideal way to distinguish an individual from other people on Earth would be to describe entire genomic DNA sequence of the person. The technique of DNA finger-printing was used for the first time by English geneticist Alec Jeffreys, in 1984.

Important for DNA fingerprinting are short nucleotide repeats which vary in number from person to person and are inherited. They are called Variable Number Tandem Repeats or VNTRs. The VNTRs of two persons may be of the same length and sequence at certain sites, but vary at other sites.

For example, a child might inherit a chromosome with six tandem repeats from the mother and the same tandem repeated four times in the homologous chromosome inherited from the father.

However, the half of VNTR alleles of the child resemble that of the mother and half that of the father.

Science Fair Project # 2. Meaning of DNA Fingerprinting:

DNA Fingerprinting is also called DNA typing or DNA profiling. This is method of ascertaining relationships and the identity of a person by means of DNA fingerprint which is unique to each individual.

The DNA fingerprint consists of the patterns of DNA fragment obtained in restriction analysis of certain highly variable repeated DNA fragments within the genome whose number and arrangement are unique for each person.

For example, two court cases are undermentioned:

a. Mr. X and Mr. Y both claim that Wilson is their son and want to take him away.

b. In another case a murder is committed and an innocent person is being implicated.

How can these cases be decided? Here DNA fingerprinting helps to solve these cases scientifically. In the first case the DNA of Mr. X and Mr. Y can be compared with that of Wilson and in the second case the blood stains or any hair found at the scene of crime can be tested for the identification of the murderer. Nowadays DNA fingerprinting has become a useful technique in forensic science to reach at correct decisions.

DNA fingerprints from a muder case

In DNA fingerprinting, DMA is extracted from evidence (A) and cut into fragments using enzymes (B). An electric current pulls the fragment through a gel, separation them in to bands (C) Which are then transferred to a nylon membrane (D)

DNA fingerprinting

DNA fingerprints of mother under consideration

Science Fair Project # 3. Principle Involved in DNA Fingerprinting:

The DNA of every individual has distinctive characteristics which is not the same for two humans except monozygotic (identical) twins. There are twenty three pairs of human chromosomes. Each set of 23 pairs of chromosomes has 1.5 million pairs of genes. The genes are segments of DNA which differ in the sequence of their nucleotides. Not all segments of DNA code for proteins.

Some DNA segments have a regulatory function, while others are intervening sequences (introns) and still others are repeated DNA sequences. The non-repetitive or unique DNA sequences form almost half of the haploid genome (DNA in one set of 23 chromosomes) and except identical twins, no two humans have genomes with same DNA nucleotide sequences.

In DNA finger printing short repetitive nucleotide sequences are quite important as they vary from person to person. They are called the Variable Number Tandem Repeats (VNTRs).

The VNTRs of two persons may be of the same length and sequences at certain sites and very at other sites. When chromosomal DNA samples are digested with restricted enzymes, DNA from different individuals yield specific patterns when subjected to gel electrophoresis.

Science Fair Project # 4. Mechanism of DNA Fingerprinting:

DNA fingerprints can be prepared from extremely minute amounts of blood, semen, hair bulk or any other cells of the body. The main steps are as follows.

The first step is called extraction. In this step DNA is extracted from any of the above mentioned cells. Thereafter many copies of this DNA are made by a technique called Polymerase Chain Reaction. Making of many copies of DNA is called amplification. Then DNA is cut with restriction enzymes into precise reproducible sequences, this is called restriction digestion.

In the next step DNA restricted sequences are then separated by gel electrophoresis, i.e., separation of DNA sequences. Now separated DNA sequences are transferred from gel onto a trinitrocellulose or nylon membrane, i.e., known as Southern blotting after the name of the inventor E. M. Southern.

Then an already available complementary DNA is made to hybridise with the isolated DNA, i.e., hybridisation. Many such DNA strands with specific nucleotide sequences complementary to VNTR sequences are available, which are called probes.

Lastly, the membrane is exposed to X-ray film on which specific bonds can be seen as depicted in the figure.

Science Fair Project # 5. Applications of DNA Fingerprinting:

a. The tests for paternity can be done for identifying the true (biological) father. The bands of child’s DNA should match the DNA prints of the biological parents.

b. Identification of the criminal is made possible by DNA fingerprinting. Here DNA finger prints of suspects and from blood or hair or semen picked up from the scene of crime are prepared and compared. The DNA fingerprint of the person matching the one obtained from sample obtained from site of crime can give clue to the actual criminal.

c. To verify whether a hopeful immigrant is, as he or she claims, really a close relative of already an established resident.

d. To identify social groups to rewrite biological evolution.

Steps in Technique of DNA Fingerprinting

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