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प्रश्न
'EcoRI' has played a very significant role in rDNA technology.
- Explain the convention for naming EcoRI.
- Write the recognition site and the cleavage sites of this restriction endonuclease.
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उत्तर
(I) Restriction endonucleases are named as follows:
1st alphabet represents the genus of the organism from which the enzyme is isolated.
2nd and 3rd alphabet represent the species of the organism.
4th alphabet represents the strain.
The Roman number represents the order of isolation or discovery of the enzyme.
EcoRI comes from the Escherichia coli RYB strain.
In EcoRI, 'E' comes from the genus 'Escherichia' and 'co' comes from the species name 'Coli'.
The letter 'R' is derived from the name of the strain RYB.
Roman numbers following the names indicate the order in which the enzymes were isolated from that strain of bacteria.
(II) The recognition sequence where EcoRI cleaves the DNA molecule is G/AATTC. Such sequences have a complementary sequence, CTTAA/G, which is known as a palindromic sequence.
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संबंधित प्रश्न
Explain with the help of a suitable example the naming of a restriction endonuclease.
How are 'sticky ends' formed on a DNA strand? Why are they so called?
Mention the difference in the mode of action of exonuclease and endonuclease.
Restriction enzymes ______.
Molecular scissors, which cut DNA at specific site is ______.
Which of the following statements does not hold true for restriction enzyme?
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?
What is elution?
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.
Identify the activity of endonuclease and exonuclease in the given image.
