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प्रश्न
How does a restriction nuclease function? Explain
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उत्तर
Restriction endonuclease functions by recognising its specific sequence. It binds to the DNA and cuts each to the two strands of the double helix at specific points in their sugar phosphate backbones. These enzymes cut the strand of DNA between the same two bases on the opposite strands leaving a single-stranded portion at their ends. These overhanging stretches are called sticky ends on each strand. The enzyme DNA ligase functions depending on the stickiness of these ends. For example, the restriction endonuclease EcoRI found in the colon bacteria E. coli recognises the base sequence GAATTC in the DNA duplex and cuts its strands between G and A.
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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.
Name the enzymes that are used for the isolation of DNA from bacterial and fungal cells for recombinant DNA technology.
Distinguish between exonuclease and endonuclease.
DNA fragments separate according to size through?
What does H in’ ‘d’ and ‘III’ refer to in the enzyme Hind III?
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.
Given below is the restriction site of a restriction endonuclease Pst-I and the cleavage sites on a DNA molecule.
\[\ce{5' C - T - G - C - A \overset{\downarrow}{-}{G 3'}}\]
\[\ce{3' G\underset{\uparrow}{-} A - C - G - T - C 5'}\]
Choose the option that gives the correct resultant fragments by the action of the enzyme Pst-I.
