How does DNA fingerprinting work?
I'm doing an assignment at the moment where we will have to produce a video for a department in my college, and my group's chosen department is Forensics.
As the video will be used as a teaching aid, this is a pretty big assignment. We've been asked to do a bit of research into the topic of the video (ours will be DNA Fingerprinting), but, alas, the internet has not been terribly helpful, and we need a more simplified explanation of the process involved in getting a DNA fingerprint.
So, if anyone can help us out, that would be lovely. Thank you!
Answers:
Like the fingerprints that came into use by detectives and police labs during the 1930s, each person has a unique DNA fingerprint. Unlike a conventional fingerprint that occurs only on the fingertips and can be altered by surgery, a DNA fingerprint is the same for every cell, tissue, and organ of a person. It cannot be altered by any known treatment. Consequently, DNA fingerprinting is rapidly becoming the primary method for identifying and distinguishing among individual human beings.
An additional application of DNA fingerprint technology is the diagnosis of inherited disorders in adults, children, and unborn babies. The technology is so powerful that, for example, even the blood-stained clothing of Abraham Lincoln could be analyzed for evidence of a genetic disorder called Marfan's Syndrome.
The characteristics of all living organisms, including humans, are essentially determined by information contained within DNA that they inherit from their parents. The molecular structure of DNA can be imagined as a zipper with each tooth represented by one of four letters (A, C, G, or T), and with opposite teeth forming one of two pairs, either A-T or G-C. The letters A, C, G, and T stand for adenine, cytosine, guanine, and thymine, the basic building blocks of DNA.
The information contained in DNA is determined primarily by the sequence of letters along the zipper. For example, the sequence ACGCT represents different information than the sequence AGTCC in the same way that the word "POST" has a different meaning from "STOP" or "POTS," even though they use the same letters. The traits of a human being are the result of information contained in the DNA code.
Living organisms that look different or have different characteristics also have different DNA sequences. The more varied the organisms, the more varied the DNA sequences. DNA fingerprinting is a very quick way to compare the DNA sequences of any two living organisms.
DNA fingerprinting is a laboratory procedure that requires six steps:
1: Isolation of DNA.
DNA must be recovered from the cells or tissues of the body. Only a small amount of tissue - like blood, hair, or skin - is needed. For example, the amount of DNA found at the root of one hair is usually sufficient.
2: Cutting, sizing, and sorting.
Special enzymes called restriction enzymes are used to cut the DNA at specific places. For example, an enzyme called EcoR1, found in bacteria, will cut DNA only when the sequence GAATTC occurs. The DNA pieces are sorted according to size by a sieving technique called electrophoresis. The DNA pieces are passed through a gel made from seaweed agarose (a jelly-like product made from seaweed). This technique is the biotechnology equivalent of screening sand through progressively finer mesh screens to determine particle sizes.
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. Each probe typically sticks in only one or two specific places on the nylon sheet.
6: DNA fingerprint.
The final DNA fingerprint is built by using several probes (5-10 or more) simultaneously. It resembles the bar codes used by grocery store scanners.
Uses of DNA Fingerprints
DNA fingerprints are useful in several applications of human health care research, as well as in the justice system.
Hope this helps!
A sample of cells are taken and centrifuged to extract the DNA.
The DNA is then amplified (Made to replicate) before an X-ray is taken of the molecules. This produces the DNA fingerprint which can be matched against others in a database, either to establish family relationships, whether a supsect was at a scene of a crime etc. etc.
Try watching some of your shows - for example CSI, Bones, believe it or not, some of the techniques they use are real. Wish I could be more helpful.
The theoretical basis of DNA fingerpring is that each individual in a spieces (apart from identical twins and clones), wheather human or horse-chestnut, has a unique DNA profile. This profile is as unique as the familiar human fingerprint itself.
much variation results from differences between individuals in terms of repeat sequences.
The technique of DNA fingerprinting,enables genetic variation to be visualized and genetic relatedness to be measured.
DNA is made up of four bases Adenine, Cytosine, Guanine and Thymine.
DNA fingerprints are from fragments of DNA called microsatellites (Each fragment is in a specific location on a chromosome called a locus). Their structure is a series of repeats of 2 or more bases e.g. CACACACA and at either end of the repeats is some simple sequence DNA. Variation in these fragments is in the number of repeats. Everyone has two copies of every microsatellite locus, one on each chromosome inherited from their parents.
To obtain a fingerprint:
1. You need a sample of DNA from the individual to be typed (fingerprinted). This is obtained from a sample of cells, from which the protein is stripped away to leave 'naked' DNA.
2. In the sample of DNA the number of copies of each microsatellite locus will be low, so to visualise the genotype at each locus more copies need to be made. This is called DNA amplification and is done using the polymerase chain reaction (PCR). It works as follows:
The DNA is mixed with 2 small fragments of DNA that bind to the simple sequence at either end of the microsatellite locus. These are called primers and one has a fluorescent label attached. Also added to the mix are the building blocks for new DNA (called dNTPs) and an enzyme called DNA polymerase which is makes new DNA.
The PCR reaction is - heat DNA to make double helix into 2 separate strands; cool to allow primers to stick to either end of the microsatellite then heat up again to allow DNA polymerase to make new DNA strands. Do this several times and then there are many new copies of the DNA.
Finally, a sample of the post-PCR DNA is separated by a process called electrophoresis. The fragments are forced through a 'gel' made of a synthetic polymer. Small fragments move more quickly than large ones. The DNA is run along side other fragments of known size and a computer program sizes each microsatellite. The fluorescent label attached to each allows visualisation.
What you end up with for each microsatellite locus is two fragments of a specific size. One individual can either have two fragments of the same size or two different sizes. These are measured in base pairs of DNA. e.g. for one locus an individual may have 2 fragments of 150 bp while another might have fragments of 140 bp and 152 bp. These are called genotypes.
Obviously for a single microsatellite there will be several individuals that share the same genotype; so genotypes for several loci are obtained for each individual until the probability that two individuals will share the the same genotype across loci is very small, this may be referred to as the DNA fingerprint or profile. For forensic purposes, the profile obtained from an individual may be compared to a sample of previously-obtained DNA.
There are many microsatellite loci dispersed throughout the chromosomes. To be useful, they need to be variable (i.e. there should be several size variants) and no one variant should be too dominant in the population. A fragment size that is in 90% of the population would not discriminate many individuals. The frequency of the variants used in forensic work has been established by population studies.
It is also import to note that different populations have different frequencies of variants so not all loci will be universally applicable. Loci used in distinguishing Europeans for example might be completely useless for example in Native populations of America as they might be a lot less variable.
Genetic fingerprinting is one of the applications of electrophoresis.
in electrophoresis restriction endonucleases are used to 'cut' the organism's DNA into sections, they're then put into a well in a slab of agar gel. The gel and DNA are covered with buffer solution which conducts electricity. Electrodes connected supply an electrical field. The phosphate groups on the DNA are negatively charged causing DNA to move towards the anode. Smaller pieces of DNA move more quickly down the agar track, whereas larger ones are much slower, this leads to the formation of bands. These can then be compared to other samples for example at a crime scene if DNA is found it is compared to that of suspects' = genetic finger printing. Probably not that useful but there ya go lol
Anybody know anything about the painkiller Co-proximal (distalgesic)?
What is the longest number?
why doesn't the moon spin on it's axis like the earth does?
full moon half moon?
Explain why the high specific heat capacity of water is important?
Why do we eat organic food , what are your perceptions of organic versus conventional food?
What is the percentage frequency of blue eyes and blond hair occuring in England and France? Which is higher?
Thevenin's theorem using this to find the current in a resistor pls help?
As the video will be used as a teaching aid, this is a pretty big assignment. We've been asked to do a bit of research into the topic of the video (ours will be DNA Fingerprinting), but, alas, the internet has not been terribly helpful, and we need a more simplified explanation of the process involved in getting a DNA fingerprint.
So, if anyone can help us out, that would be lovely. Thank you!
Answers:
Like the fingerprints that came into use by detectives and police labs during the 1930s, each person has a unique DNA fingerprint. Unlike a conventional fingerprint that occurs only on the fingertips and can be altered by surgery, a DNA fingerprint is the same for every cell, tissue, and organ of a person. It cannot be altered by any known treatment. Consequently, DNA fingerprinting is rapidly becoming the primary method for identifying and distinguishing among individual human beings.
An additional application of DNA fingerprint technology is the diagnosis of inherited disorders in adults, children, and unborn babies. The technology is so powerful that, for example, even the blood-stained clothing of Abraham Lincoln could be analyzed for evidence of a genetic disorder called Marfan's Syndrome.
The characteristics of all living organisms, including humans, are essentially determined by information contained within DNA that they inherit from their parents. The molecular structure of DNA can be imagined as a zipper with each tooth represented by one of four letters (A, C, G, or T), and with opposite teeth forming one of two pairs, either A-T or G-C. The letters A, C, G, and T stand for adenine, cytosine, guanine, and thymine, the basic building blocks of DNA.
The information contained in DNA is determined primarily by the sequence of letters along the zipper. For example, the sequence ACGCT represents different information than the sequence AGTCC in the same way that the word "POST" has a different meaning from "STOP" or "POTS," even though they use the same letters. The traits of a human being are the result of information contained in the DNA code.
Living organisms that look different or have different characteristics also have different DNA sequences. The more varied the organisms, the more varied the DNA sequences. DNA fingerprinting is a very quick way to compare the DNA sequences of any two living organisms.
DNA fingerprinting is a laboratory procedure that requires six steps:
1: Isolation of DNA.
DNA must be recovered from the cells or tissues of the body. Only a small amount of tissue - like blood, hair, or skin - is needed. For example, the amount of DNA found at the root of one hair is usually sufficient.
2: Cutting, sizing, and sorting.
Special enzymes called restriction enzymes are used to cut the DNA at specific places. For example, an enzyme called EcoR1, found in bacteria, will cut DNA only when the sequence GAATTC occurs. The DNA pieces are sorted according to size by a sieving technique called electrophoresis. The DNA pieces are passed through a gel made from seaweed agarose (a jelly-like product made from seaweed). This technique is the biotechnology equivalent of screening sand through progressively finer mesh screens to determine particle sizes.
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. Each probe typically sticks in only one or two specific places on the nylon sheet.
6: DNA fingerprint.
The final DNA fingerprint is built by using several probes (5-10 or more) simultaneously. It resembles the bar codes used by grocery store scanners.
Uses of DNA Fingerprints
DNA fingerprints are useful in several applications of human health care research, as well as in the justice system.
Hope this helps!
A sample of cells are taken and centrifuged to extract the DNA.
The DNA is then amplified (Made to replicate) before an X-ray is taken of the molecules. This produces the DNA fingerprint which can be matched against others in a database, either to establish family relationships, whether a supsect was at a scene of a crime etc. etc.
Try watching some of your shows - for example CSI, Bones, believe it or not, some of the techniques they use are real. Wish I could be more helpful.
The theoretical basis of DNA fingerpring is that each individual in a spieces (apart from identical twins and clones), wheather human or horse-chestnut, has a unique DNA profile. This profile is as unique as the familiar human fingerprint itself.
much variation results from differences between individuals in terms of repeat sequences.
The technique of DNA fingerprinting,enables genetic variation to be visualized and genetic relatedness to be measured.
DNA is made up of four bases Adenine, Cytosine, Guanine and Thymine.
DNA fingerprints are from fragments of DNA called microsatellites (Each fragment is in a specific location on a chromosome called a locus). Their structure is a series of repeats of 2 or more bases e.g. CACACACA and at either end of the repeats is some simple sequence DNA. Variation in these fragments is in the number of repeats. Everyone has two copies of every microsatellite locus, one on each chromosome inherited from their parents.
To obtain a fingerprint:
1. You need a sample of DNA from the individual to be typed (fingerprinted). This is obtained from a sample of cells, from which the protein is stripped away to leave 'naked' DNA.
2. In the sample of DNA the number of copies of each microsatellite locus will be low, so to visualise the genotype at each locus more copies need to be made. This is called DNA amplification and is done using the polymerase chain reaction (PCR). It works as follows:
The DNA is mixed with 2 small fragments of DNA that bind to the simple sequence at either end of the microsatellite locus. These are called primers and one has a fluorescent label attached. Also added to the mix are the building blocks for new DNA (called dNTPs) and an enzyme called DNA polymerase which is makes new DNA.
The PCR reaction is - heat DNA to make double helix into 2 separate strands; cool to allow primers to stick to either end of the microsatellite then heat up again to allow DNA polymerase to make new DNA strands. Do this several times and then there are many new copies of the DNA.
Finally, a sample of the post-PCR DNA is separated by a process called electrophoresis. The fragments are forced through a 'gel' made of a synthetic polymer. Small fragments move more quickly than large ones. The DNA is run along side other fragments of known size and a computer program sizes each microsatellite. The fluorescent label attached to each allows visualisation.
What you end up with for each microsatellite locus is two fragments of a specific size. One individual can either have two fragments of the same size or two different sizes. These are measured in base pairs of DNA. e.g. for one locus an individual may have 2 fragments of 150 bp while another might have fragments of 140 bp and 152 bp. These are called genotypes.
Obviously for a single microsatellite there will be several individuals that share the same genotype; so genotypes for several loci are obtained for each individual until the probability that two individuals will share the the same genotype across loci is very small, this may be referred to as the DNA fingerprint or profile. For forensic purposes, the profile obtained from an individual may be compared to a sample of previously-obtained DNA.
There are many microsatellite loci dispersed throughout the chromosomes. To be useful, they need to be variable (i.e. there should be several size variants) and no one variant should be too dominant in the population. A fragment size that is in 90% of the population would not discriminate many individuals. The frequency of the variants used in forensic work has been established by population studies.
It is also import to note that different populations have different frequencies of variants so not all loci will be universally applicable. Loci used in distinguishing Europeans for example might be completely useless for example in Native populations of America as they might be a lot less variable.
Genetic fingerprinting is one of the applications of electrophoresis.
in electrophoresis restriction endonucleases are used to 'cut' the organism's DNA into sections, they're then put into a well in a slab of agar gel. The gel and DNA are covered with buffer solution which conducts electricity. Electrodes connected supply an electrical field. The phosphate groups on the DNA are negatively charged causing DNA to move towards the anode. Smaller pieces of DNA move more quickly down the agar track, whereas larger ones are much slower, this leads to the formation of bands. These can then be compared to other samples for example at a crime scene if DNA is found it is compared to that of suspects' = genetic finger printing. Probably not that useful but there ya go lol
The answers post by the user, for information only, UKQnA.com does not guarantee the right.