Read the following and answer the question given below : Restriction ...
Restriction endonuclease was isolated for the first time from the bacterium Haemophilus influenzae (prokaryotic cell).
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Read the following and answer the question given below : Restriction ...
Restriction endonucleases are enzymes that are found in bacteria and have the ability to cut DNA at specific recognition sites. They play a crucial role in DNA manipulation and are widely used in recombinant DNA technology.
First Isolation of Restriction Endonuclease:
- Restriction endonuclease was first isolated by W. Aber in 1962 in bacteria.
- The discovery of restriction endonucleases revolutionized the field of molecular biology as it provided a tool to manipulate DNA sequences.
Types of Restriction Endonucleases:
- There are three types of restriction endonucleases: Type I, Type II, and Type III.
- Type I and Type III restriction endonucleases are complex enzymes that require ATP hydrolysis for their activity and are not commonly used in recombinant DNA technology.
- Type II restriction endonucleases are the most commonly used enzymes in recombinant DNA technology as they recognize specific DNA sequences and cleave the DNA at precise locations.
Restriction Endonuclease EcoR I:
- EcoR I is a Type II restriction endonuclease that recognizes the specific DNA sequence GAATTC.
- It cuts the DNA duplex between the G and A in the recognition sequence.
- The resulting DNA fragments have sticky ends, which can be ligated with other DNA fragments that have been cut with the same restriction enzyme.
- EcoR I is one of the most extensively studied and commonly used restriction endonucleases in molecular biology.
Isolation of Restriction Endonucleases from Prokaryotic Cells:
- The correct answer to the question is option 'C' - prokaryotic cell.
- Prokaryotic cells, such as bacteria, are the natural source of restriction endonucleases.
- These enzymes are part of the bacterial defense system against foreign DNA, such as bacteriophages.
- The isolation of restriction endonucleases from prokaryotic cells allows researchers to study their properties, sequence specificity, and use them in various applications, including recombinant DNA technology.
In summary, restriction endonucleases were first isolated by W. Aber in 1962 from prokaryotic cells. They are enzymes that recognize specific DNA sequences and cleave the DNA at precise locations. Among the three types of restriction endonucleases, Type II enzymes, such as EcoR I, are commonly used in recombinant DNA technology. EcoR I recognizes the sequence GAATTC and cuts the DNA duplex between G and A. The isolation of restriction endonucleases from prokaryotic cells has been instrumental in advancing molecular biology and genetic engineering techniques.
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