DNA from two different people may have different sequences in the non-coding regions of their DNA. These differences may result in one person having a particular restriction site and the other person not having it. Different numbers and types of restriction sites will cause different fragments to be produced.
This is because there might not be one restriction site bordering the gene to be cloned and the identical restriction site in the plasmid. Since these two restriction enzymes make compatible sticky ends, the insert has a chance of combining with the plasmid. To ensure efficient digestion, the two recognition sites should be more than 10 base pairs apart. If one of the enzymes is a poor cutter or if the sites are separated 10 base pairs or less, the digestions should be performed sequentially
Restriction enzymes always 'cut' the DNA where a particular short sequence of bases occurs. These short sequences will not occur at the same points along the DNA in genetically different individuals...
The enzymes recognize different restriction sites.
Different restriction enzymes will cut the DNA stand at different site, or in other words after a different series of pairs.
restriction enzymes or endonuclease enzymes
As the DNA fragments results from the action of the restriction enzymes and on the other hand mutations alter the sites where the restriction enzymes react therefore there is difference in number and of length of each fragment from person to person.
Plasmids are circular pieces of DNA, so the number of fragments equals the number of cuts from the restriction enzymes. You can easily see this if you start with one restriction enzyme that cuts the plasmid in only one place. Cutting the circle in one place yields you only one fragment. If the restriction cuts in two places, you end up with two fragments; with three places, three fragments, etc. With linear chromosomes, the situation is different. Cutting a linear chromosome in one place yields two fragments, cutting in two places yields three fragments, etc. So the number of fragments is always one more than the number of cuts. A restriction map of a plasmid will show all of the cuts the restriction enzymes made. Each cut is labeled with the enzyme that made it. One can count the spaces between cuts to determine the number of fragments that are produced. Restriction maps usually (but not always) also show the size of each fragment.
DNA can be cut into smaller fragments by enzymes (which are proteins) known as restriction endonucleases (REN's). These enzymes are sequence specific - meaning they produce a cut only at a particular site on the DNA strand. This site where the cut is produced is called the restriction site. Restriction sites are 4 - 6 nucleotides in length. Every restriction enzyme has a different restriction site. This property allows researchers to treat two different DNA samples with the same set of restriction enzymes and then analyze the resulting fragments.A. DNA finger printing
The chemicals used to cut DNA fragments are restriction endonucleases, eg- Eco R I, Eco R II,etc
cutting of DNA into fragments simply means application of suitable restriction enzyme to it.now a days two types of restriction enzymes are available,1)exonucleases,which cut at end portion of DNA and 2)endonucleases ,which cut at specific inner site.
Restriction enzymes. Babe
restriction enzymes or endonuclease enzymes
In a practical application, we need a Book; it will also say which restriction enzymes leave the longest fragments.
When DNA is treated with restriction enzymes, and the fragments are loaded onto a gel which is subjected to electrophoresis, we get a banding pattern of the DNA fragments with the farthest band (from the gel) of those fragments smallest in size.
A restriction map plots restriction sites within a chain of DNA. You cannot create a restriction map without restriction enzymes. Restriction sites are points in a DNA molecule that contain certain strings of nucleotides, which can only be identified by restriction enzymes.
Through the process of gel electrophoresis.
DNA is of a negative charge. So when gel electrophoresis is used on it the DNA fragments are attracted to the positive end of the electrophoresis. The fragments of different lengths travel down the gel towards this end. The longer length fragments travel less and so are farther from the positive end. By looking at these DNA fragments, which are created by cutting DNA with restriction enzymes one can compare and contrast DNA. Thus DNA fingerprinting can take place based on the different restriction sites in DNA (cut by the enzymes) forming different length segments of DNA.
For DNA gel electrophoresis, yes. Once the DNA is cut up into different-sized fragments, they can be electrophoresed to separate bands.
As the DNA fragments results from the action of the restriction enzymes and on the other hand mutations alter the sites where the restriction enzymes react therefore there is difference in number and of length of each fragment from person to person.
Restriction enzymes, also known as restriction endonucleases, are used to cut DNA into smaller fragments. Restriction enzymes are found in bacteria, where they act like molecular scissors by cutting up DNA from invading viruses or bacteriophages. Each restriction enzyme recognizes a specific nucleotide sequence and cuts the DNA at that site. This process makes restriction enzymes extremely useful in biotechnology where they are used in procedures such as DNA cloning, DNA fingerprinting, and genetic engineering. There are hundreds of known restriction enzymes, and each one was named for the bacteria from which it was isolated. For example, EcoRI was isolated from Escherichia coli and HaeIII from Haemophilus aegyptius.
A DNA LibraryA collection of cells containing DNA fragments produced by restriction enzymes and incorporated into plasmids is called a DNA library. RNA can manufacture DNA via the action of reverse transcriptase.