What is DNA Fingerprinting?

Brendan McGuigan

DNA fingerprinting is a way of identifying a specific individual, rather than simply identifying a species or some particular trait. It is also known as genetic fingerprinting or DNA profiling. As a technology, it has been around since at least 1985, when it was announced by its inventor, Sir Alec Jeffreys. DNA fingerprinting is currently used both for identifying paternity or maternity and for identifying criminals or victims. There is discussion of using DNA fingerprinting as a sort of personal identifier as well, although the viability of this is debatable.

Fingerprints might be left at a crime scene.
Fingerprints might be left at a crime scene.

The vast majority of a human's DNA will match exactly that of any other human, making distinguishing between two people rather difficult. DNA fingerprinting uses a specific type of DNA sequence, known as a microsatellite, to make identification much easier. Microsatellites are short pieces of DNA which repeat many times in a given person's DNA. In a given area, microsatellites tend to be highly variable, making them ideal for DNA fingerprinting. By comparing a number of microsatellites in a given area, one can identify a person relatively easily.

DNA fingerprinting can establish a criminal's guilt.
DNA fingerprinting can establish a criminal's guilt.

The sections of DNA used in DNA fingerprinting, although highly variable, are passed down from parents to their children. Although not all of the sections will necessarily be passed on, no child has pairs that their parents do not have. This means that by comparing large groups of these sections, paternity, maternity, or even both, may be determined. DNA fingerprinting has a high success rate and a very low false-positive rate, making it an extremely popular form of paternity and maternity verification.

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The majority of a human's DNA will match that of any other human.
The majority of a human's DNA will match that of any other human.

In forensics, DNA fingerprinting is very attractive because it doesn't require actual fingerprints, which may or may not be left behind, and may or may not be obscured. Because all of the DNA sections are contained in every cell, any piece of a person's body, from a strand of hair to a skin follicle to a drop of blood, may be used to identify them using DNA fingerprinting. This is useful in the case of identifying a criminal, because even a drop of blood or skin left at the crime scene may be enough to establish innocence or guilt, and it is virtually impossible to remove all physical trace of one's presence. DNA fingerprinting is useful in the case of identifying victims because even in cases where the body may be disfigured past identification, and teeth or other identifying features may be destroyed, all it takes is a single cell for positive identification.

The sections of DNA used in DNA fingerprinting are passed doen from parents to their children.
The sections of DNA used in DNA fingerprinting are passed doen from parents to their children.

DNA fingerprinting is by no means perfect, however. It cannot establish beyond the shadow of a doubt that a specific cell comes from a specific person; it can only establish a probability. In many cases this probability is very high -- one in ten billion, for example -- but in some cases it may be much lower. The probability also becomes obscured when dealing with direct descendents, who may share a large portion of the examined areas of DNA with a parent.

Despite these problems, DNA fingerprinting is becoming more and more prevalent in the world of criminal forensics. Though some legal questions exist, such as the conclusiveness of DNA fingerprinting and the extent to which it is legal by national laws to compile databases of people's DNA and to take samples of their DNA for comparison, the benefits currently seem to outweigh the problems.

DNA fingerprinting is becoming increasingly prevalent in the world of criminal forensics.
DNA fingerprinting is becoming increasingly prevalent in the world of criminal forensics.

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Discussion Comments

anon163343

anon 19583 just to correct a mistake you have made: DNA stands for Deoxyribo-neucleic-acid not deoxyribo-ascorbic-acid as that would make it DAA.

anon158236

Yes, a DNA (Deoxyribo Ascorbic Acid) Database is a location which holds the results of a DNA Fingerprint. The biggest in america is run by the government.

most are government owned but some are private. And i do not think that two identical twins could be distinguished from one another by a DNA test. You are right about them having different fingerprints, as these are formed in the womb and are not affected by DNA. But if they are not affected by DNA, i do not think that there would be a allele or a set of them which would code for this characteristic.

Post to anon54709 DNA: is in nearly every one of your cells mature red blood cells do nor contain DNA and Gametes have only half the number of chromosomes.

@anon105105: DNA sequencing is similar but it involves coding the whole of your DNA, all of the bases. An example of this is the Human Genome project completed in 2003.

@anon48668: Maybe, but you have to understand that the sperm cell is a Gamete containing only half of the person's specific DNA. Therefore matching this up to the rapist could be hard. Hope the info helps.

anon126840

everything that in page is interesting but i have a question. Does a DNA database have something to do with DNA profiling and how?

anon126326

Twins' finger printing and DNA would be slightly different because your fingerprints take the shape of which environment you're in and what you do daily and also the things you go through. Such as a horse rider would have different fingerprints from an artist. See the trend? hope that helped.

anon105869

how about twins? don't they have the same DNA? they're identical, right?

anon105105

How are DNA fingerprinting and DNA sequencing similar?

anon99305

Does everyone have the same fingerprint?

anon91822

Why is DNA fingerprinting important for forensic scientists?

anon89739

what are two ways this method is useful?

anon76812

can a hug or a kiss on the forehead leave dna two to three days later?

anon72232

what is the maximum lifespan of a dna molecule?

anon71228

how do you identify DNA?

anon71225

Dna is interesting the way it interacts and creates life is interesting.

anon67731

Can DNA fingerprinting help in identification of species?

anon65549

I'm still wondering what are some of the major problems that still exist within DNA fingerprinting.

anon63250

I'd just like to say that no you can't change your fingerprints but the good news is not everyone has the same fingerprint.

i study forensic science and so far i can tell you that everyone has their own unique fingerprint. dna can tell you what your blood type is because dna is in your blood cells, and to answer anon48668's question about the rape, yes the sperm can get traced back if at early staged otherwise the answer is no.

And to anon52828's question, it is used a lot but the problem with fingerprinting is that you cannot convict someone with just the fingerprints. Otherwise a lot of other people would be getting convicted in this world for no reason.

anon60053

actually DNA is not contained in hemolymph or red blood cells because they do not have a nucleus. the massive hemoglobin protein contained within the red blood cell does not allow for a nucleus. You make new red blood cells from the stem cells located in your sternum and pelvis.

anon56388

how can dna help scientists?

anon55609

I would like to know the answer to that previous question about finding a person's rapist based on the sperm ejaculation.

anon54709

yes! DNA can tell you your blood type, because dna is in all your cells -- every single one of them.

anon53202

pooh42: if they have some of Dick's DNA to begin with, then yes.

anon52828

how often is DNA fingerprinting used to solve a crime?

anon51227

can a dna of a person be changed and matched to another person?

anon51187

i think that DNA is extremely interesting. we are actually learning about that in school. and this article really helped. thanks!

anon50860

anon48668 has a good question. :)

anon48668

DNA is quite unique, but i honestly don't know how it was invented. i have a question too! if a girl gets raped and the male ejaculates in her, can they trace the sperm to the rapist?

anon48442

how can we make a simple experiment of a dna finger print?

anon47087

can you change your fingerprints?

anon35699

How does Dna fingerprinting and modern genetics research help historians, palaeontologists and archeologists in their research in connection with genetic science and the study of mankind's past?

pooh42

Can DNA tell if a person is the result of incest? For example: If a man rapes the daughter of his biological sister; i.e., Dick and Jane are brother and sister. Jane has a daughter named Dorothy. Dick rapes Dorothy. Dick, Jane and Dorothy are now dead. Can Dorothy's child (fathered by Dick) have his/her DNA tested to determine inception by incest?

anon31525

How are DNA fingerprinting and DNA sequencing similar?

anon27982

Hi. I just have a couple of questions to ask about dna fingerprinting.

Q1- how is dna fingerprinting is obtained?

Q2- why do suspects have the right to refuse to supply samples for dna fingerprinting?

Q3- what is the danger of compulsory dna fingerprints?

anon19586

A blood test can tell you what blood group you are, but DNA is responsible for determining this in the first place.

lesquilin

can dna tell me what blood type i have?

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