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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
How are 'sticky ends' formed on a DNA strand? Why are they so called?
Suggest a technique to a researcher who needs to separate fragments of DNA.
Make a chart (with diagrammatic representation) showing a restriction enzyme, the substrate DNA on which it acts, the site at which it cuts DNA and the product it produces.
Do eukaryotic cells have restriction endonucleases? Justify your answer.
Collect 5 examples of palindromic DNA sequences. Better try to create a palindromic sequence by following base-pair rules.
Distinguish between exonuclease and endonuclease.
Answer the following question.
Explain the significance of palindromic nucleotide sequence in the formation of recombinant DNA.
The DNA fragment separated on an agarose gel can be visualized by staining with ______.
Which of the following radioisotope is not suitable for DNA labeling based studies?
Restriction enzymes ______.
Molecular scissors, which cut DNA at specific site is ______.
'Restriction' in restriction enzyme refers to
DNA fragments separate according to size through?
A specific recognition sequence identified by endonucleases to make cuts at specific positions within the DNA is ______
Which of the given statements is correct in the context of visualizing DNA molecules separated by agarose gel electrophoresis?
'Restriction' in Restriction enzyme refers to ______.
The role of DNA ligase in the construction of a recombinant DNA molecule is ______.
Would you choose an exonuclease while producing a recombinant DNA molecule?
What does H in’ ‘d’ and ‘III’ refer to in the enzyme Hind III?
Restriction enzymes should not have more than one site of action in the cloning site of a vector. Comment.
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.
How does one visualise DNA on an agarose gel?
What is elution?
What are the protruding and hanging stretches of DNA produced by these restriction enzymes called? Describe their role in the formation of rDNA.
State the principle involved in separation of DNA fragments using gel electrophoresis.
How are DNA fragments visualised once they are separated by gel electrophoresis?
