Biotechnological techniques
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Cleavage of DNA sequence using restriction enzyme EcoRI.
(a) EcoRI scans the DNA molecule.
(b) EcoRI binds to the recognition site
(c) EcoRI disrupts the phosphodiester bonds.
Two fragments with complementary ends are produced.
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the role of restriction enzymes in the immune system.
When a virus (known as a bacteriophage) attacks a bacterial cell, it injects its DNA into the bacterium and leaves its protein coat outside the cell wall. As bacteriophage DNA is being injected into a bacterial cell, the bacteria’s restriction endonuclease starts to scan this foreign DNA, looking for recognition sites. Because recognition sites inevitably exist in the foreign DNA, the restriction endonuclease cleaves the bacteriophage DNA into fragments (Fi The bacteriophage DNA is inactivated. Fragments cannot be transcribed or translated into anything useful. The bacteria cell’s own genome is protected and it can continue functioning as a bacterial cell, as opposed to a bacteriophage production factory.
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Naming of restriction enzymes
Restriction enzymes are named according to the bacteria from which they originate. For example, the restriction enzyme BamHI is named as follows:
B represents the genus Bacillus
am represents the species amyloliquefaciens
H represents the strain
I means that it was the first endonuclease isolated from this strain
Following the same pattern, the rationale for the name of the restriction enzyme
HindII is the following:
H represents the genus Haemophilus
in represents the species influenzae
d represents the strain Rd
II means that it was the second endonuclease isolated from this strain
Generally speaking, the first letter is the initial of the genus name of the organism
from which the enzyme is isolated. The second and third letters are usually the initial letters of the species name. The fourth letter indicates the strain, while the numerals indicate the order of discovery of that particular enzyme from that strain of bacteria.
This an animation on how to make a recombinant DNA. Teachers can make learning fun and inspire the students to reach their full potential. Encourage your students to make their own animation using the power point, as in the example below. This activity keep students engaged while they are learning about the Recombinant DNA