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How can a bacterium produce restriction enzymes that do not cleave its DNA?
Wiki User
∙ 11y ago
In order to protect the bacterial genomic DNA from its own restriction enzymes, bacterial cells employ a system, wherein methyl transferases methylate certain bases on the DNA sequence, making them unrecognizable to the restriction enzymes.
Each restriction enzyme has a methylase associated with it on the chromosome. This methylase puts methyl groups on the host DNA, and the restriction enzyme doesn't recognize its recognition sequence when it is so methlyated. The host DNA is thus protected from the actions of its own restriction enzyme.
Incoming (foreign) DNA is unlikely to be protected (methylated) in the same manner, thus this invading DNA is digested by the hosts restriction enzyme(s).
When working in cloning experiments, the principle is the same -- DNA to be digested is carried by a plasmid in a host that does not methylate DNA in the pattern that would cause the restriction enzyme to see it as protected, thus it is cut. DNA generated by PCR is similarly unmethylated, and is therefore also digested.
Some enzymes won't cut DNA isolated from dam+ or dcm+ hosts (two common bacterial methylases), thus one must know the genotype of the host cloning strain if using a restriction enzyme whose action is blocked by dam ordcmmethylation.
Wiki User
∙ 12y ago
Wiki User
∙ 11y agoRestriction enzymes cleave DNA at a particular recognition site -- a particular sequence of nucleotides. You can imagine the following scenarios:
1. The bacterial chromosome does not contain the recognition sequence
2. The bacterial chromosome contains the recognition sequence, but that particular part of the DNA is either supercoiled to keep the restriction enzyme from finding the sequence, or it's single stranded as when being replicated or transcribed.
3. The bacterial chromosome contains the recognition sequence, but that particular part of the DNA is methylated or modified in some other way which prevents the restriction enzyme from attaching.
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DNA strands can be clipped crosswise at selected positions by using enzymes called?
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
Why the first restriction endonuclease is known as Hind2 and not Hind1?
Restriction enzymes are named based on the organism in which they were discovered. For example, the enzyme Hind III was isolated from Haemophilus influenzae, strain Rd. The first three letters of the name are italicized because they abbreviate the genus and species names of the organism. The fourth letter typically comes from the bacterial strain designation. The Roman numerals are used to identify specific enzymes from bacteria that contain multiple restriction enzymes. Typically, the Roman numeral indicates the order in which restriction enzymes were discovered in a particular strain.There are three classes of restriction enzymes, labeled types I, II, and III. Type I restriction systems consist of a single enzyme that performs both modification (methylation) and restriction activities. These enzymes recognize specific DNA sequences, but cleave the DNA strand randomly, at least 1,000 base pairs(bp) away from the recognition site. Type III restriction systems have separateenzymes for restriction and methylation, but these enzymes share a common subunit. These enzymes recognize specific DNA sequences, but cleave DNA at random sequences approximately twenty-five bp from the recognition sequence. Neither type I nor type III restriction systems have found much application in recombinant DNA techniques.Type II restriction enzymes, in contrast, are heavily used in recombinant DNA techniques. Type II enzymes consist of single, separate proteins for restriction and modification. One enzyme recognizes and cuts DNA, the other enzyme recognizes and methylates the DNA. Type II restriction enzymes cleave the DNA sequence at the same site at which they recognize it. The only exception are type IIs (shifted) restriction enzymes, which cleaveDNA on one side of the recognition sequence, within twenty nucleotides of the recognition site. Type II restriction enzymesdiscovered to date collectively recognize over 200 different DNA sequences.
What is the substance required to cleave the vector DNA during recombinant DNA technology?
A restriction enzyme, also called a restriction endonuclease, is needed to cleave vector DNA when using recombinant DNA technology.
What is the function of restriction enzymes that naturally occur in bacteria cells?
Restiriction enzymes, or endonucleases, splice (cut) apart two different sites of the nucleotide sequence on foreign DNA resulting in two different pieces of DNA for a gene of interest to be inserted. This usually occurs in bacteria such as E. coli and such. Once the two cuts have been made (one at 5' and one at 3') there remains the open ends of the DNA called 'sticky ends'. THis is where the gene of interest is inserted.
Function of hindiii?
Haemophilus influenzae is a species of bacteria that is the source of the HindIII restriction enzyme that cleaves the palindromic DNA sequence 5'-AAGCTT-3' in the presence of the cofactor Mg2+ via hydrolysis. While restriction enzymes cleave at specific DNA sequences, they are first required to bind non-specifically with the DNA backbone before localizing to the restriction site. On average, the restriction enzyme will form 15-20 hydrogen bonds with the bases of the recognition sequence. With the aid of other Van der Waals interactions, this bonding facilitates a conformational change of the DNA-enzyme complex which leads to the activation of catalytic centers. Despite the lack of evidence suggesting an exact mechanism for the cleavage of DNA by HindIII, site-mutagenesis analysis coupled with more detailed studies of metal ion-mediated catalysis in EcoRV have led to the following proposed catalytic mechanism. It has been suggested that during the hydrolysis of DNA by EcoRV the catalytic residue Lys-92 stabilizes and orients the attacking water nucleophile, while the carboxylate of Asp-90 stabilizes the leaving hydroxide anion through to coordination of Mg2
What is the difference between Restriction endonucleases and exonucleases?
Exonuclease enzymes cleave nucleotides from the ends of DNA molecules. Endonuclease enzymes cleave a phosphodiester bond somewhere within the DNA molecule (not at the ends).
What are used to cleave DNA into fragments?
Restriction enzymes. Babe
How can bacterium produce restriction enzymes that do not cleave it's DNA?
Restriction enzymes cleave DNA at a particular recognition site -- a particular sequence of nucleotides. You can imagine the following scenarios:1. The bacterial chromosome does not contain the recognition sequence2. The bacterial chromosome contains the recognition sequence, but that particular part of the DNA is either supercoiled to keep the restriction enzyme from finding the sequence, or it's single stranded as when being replicated or transcribed.3. The bacterial chromosome contains the recognition sequence, but that particular part of the DNA is methylated or modified in some other way which prevents the restriction enzyme from attaching.
Can virus get a bacteria?
Yes- Bacterial viruses are called bacteriophages. Some examples are T4 and T7 phages. They are complex DNA viruses that attach themselves to the cell surface and then inject their DNA to the inside of the bacteria. Bacteria have enzymes called restriction enzymes that cleave DNA at specific sites called restriction sites. These enzymes are the bacterium's defense against phages.
Where restriction enzymes come from?
Restriction enzyme, also called restriction endonuclease, a protein produced by bacteria that cleaves DNA at specific sites along the molecule. In the bacterial cell, restriction enzymes cleave foreign DNA, thus eliminating infecting organisms.
What is the enzyme function of restriction enzymes?
We believe the function of the restriction enzyme is to protect an organism from foreign DNA as restriction enzymes cleave DNA strands (making them useless). The idea is that bacteria use this to protect against viral infection as viruses attach to the cell and insert their DNA into it in order to "take over" the cell. Restriction enzymes recognize this DNA as foreign and begin to chop it up, saving the cell.
DNA strands can be clipped crosswise at selected positions by using enzymes called?
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
How are restriction enzymes used to look for differences between DNA samples?
Restriction enzymes cleave, or open, the DNA so that a sample can be taken and gel electrophoresis can separate the strands of DNA. From there, DNA probes bind to certain strands in each sample and DNA fingerprints can show the differences.
Why the first restriction endonuclease is known as Hind2 and not Hind1?
Restriction enzymes are named based on the organism in which they were discovered. For example, the enzyme Hind III was isolated from Haemophilus influenzae, strain Rd. The first three letters of the name are italicized because they abbreviate the genus and species names of the organism. The fourth letter typically comes from the bacterial strain designation. The Roman numerals are used to identify specific enzymes from bacteria that contain multiple restriction enzymes. Typically, the Roman numeral indicates the order in which restriction enzymes were discovered in a particular strain.There are three classes of restriction enzymes, labeled types I, II, and III. Type I restriction systems consist of a single enzyme that performs both modification (methylation) and restriction activities. These enzymes recognize specific DNA sequences, but cleave the DNA strand randomly, at least 1,000 base pairs(bp) away from the recognition site. Type III restriction systems have separateenzymes for restriction and methylation, but these enzymes share a common subunit. These enzymes recognize specific DNA sequences, but cleave DNA at random sequences approximately twenty-five bp from the recognition sequence. Neither type I nor type III restriction systems have found much application in recombinant DNA techniques.Type II restriction enzymes, in contrast, are heavily used in recombinant DNA techniques. Type II enzymes consist of single, separate proteins for restriction and modification. One enzyme recognizes and cuts DNA, the other enzyme recognizes and methylates the DNA. Type II restriction enzymes cleave the DNA sequence at the same site at which they recognize it. The only exception are type IIs (shifted) restriction enzymes, which cleaveDNA on one side of the recognition sequence, within twenty nucleotides of the recognition site. Type II restriction enzymesdiscovered to date collectively recognize over 200 different DNA sequences.
What is the substance required to cleave the vector DNA during recombinant DNA technology?
A restriction enzyme, also called a restriction endonuclease, is needed to cleave vector DNA when using recombinant DNA technology.
What is the function of restriction enzymes that naturally occur in bacteria cells?
Restiriction enzymes, or endonucleases, splice (cut) apart two different sites of the nucleotide sequence on foreign DNA resulting in two different pieces of DNA for a gene of interest to be inserted. This usually occurs in bacteria such as E. coli and such. Once the two cuts have been made (one at 5' and one at 3') there remains the open ends of the DNA called 'sticky ends'. THis is where the gene of interest is inserted.
Function of restriction enzymes?
They cut strands of DNA at specific sites.
