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प्रश्न
Explain briefly:
Restriction enzymes and DNA
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उत्तर
Restriction enzymes are used to break up DNA molecules. They are part of a broader enzyme class known as nucleases. Restriction enzymes are classified into three types:
- Exonucleases: They remove nucleotides from the terminal ends (5' or 3') of one double strand of DNA.
- Endonucleases: They make cuts at specific positions within the DNA. These enzymes don’t fragment the ends and only affect one strand of the DNA helix.
- Restriction endonucleases: Arber identified them in bacteria in 1963. They function as “molecular scissors” or chemical scalpels. They detect the base sequence at palindrome sites in DNA sequences and sever the strands. There are three types of restriction endonucleases: type I, type II, and type III. Only type II restriction enzymes are utilised in recombinant DNA technology because they can recognise and cut inside a specified DNA sequence, typically consisting of 4 to 8 nucleotides.
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संबंधित प्रश्न
Explain with the help of a suitable example the naming of a restriction endonuclease.
Mention the difference in the mode of action of exonuclease and endonuclease.
Suggest a technique to a researcher who needs to separate fragments of DNA.
How does a restriction nuclease function? Explain
Name and describe the technique that helps in separating the DNA fragments formed by the use of restriction endonuclease
Explain the roles of the following with the help of an example each in recombinant DNA technology :
Restriction Enzymes
Answer the following question.
Write the use of restriction endonuclease in the formation of recombinant DNA.
The DNA fragment separated on an agarose gel can be visualized by staining with ______.
A mixture containing DNA fragments a, b, c and d, with molecular weights of a + b = c, a > b and d > c was subject to agarose get electrophoresis. This position of these fragments from cathode to anode to anode sides of the gel would be ______.
Which of the following radioisotope is not suitable for DNA labeling based studies?
Molecular scissors, which cut DNA at specific site is ______.
DNA strands on a gel stained with ethidium bromide when viewed under UV radiation, appear as ______
Which of the given statements is correct in the context of visualizing DNA molecules separated by agarose gel electrophoresis?
In agarose gel electrophoresis, DNA molecules are separated on the basis of their ______.
The role of DNA ligase in the construction of a recombinant DNA molecule is ______.
Which of the following statements does not hold true for restriction enzyme?
Would you choose an exonuclease while producing a recombinant DNA molecule?
Restriction enzymes that are used in the construction of recombinant DNA are endonucleases which cut the DNA at ‘specific-recognition sequence’. What would be the disadvantage if they do not cut the DNA at specific-recognition sequence?
A plasmid DNA and a linear DNA (both are of the same size) have one site for a restriction endonuclease. When cut and separated on agarose gel electrophoresis, plasmid shows one DNA band while linear DNA shows two fragments. Explain.
What is elution?
State the importance of elution in this process.
What are the protruding and hanging stretches of DNA produced by these restriction enzymes called? Describe their role in the formation of rDNA.
How are DNA fragments visualised once they are separated by gel electrophoresis?
Identify the activity of endonuclease and exonuclease in the given image.
