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प्रश्न
Distinguish between exonuclease and endonuclease.
Differentiate between exonuclease and endonuclease.
Discuss with your teacher and find out how to distinguish between exonuclease and endonuclease.
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उत्तर १
| Sr. No. | Exonuclease | Endonuclease |
| 1. | It is a type of restriction enzyme that removes the nucleotide from the 5' or 3' ends of the DNA molecule. | It is a type of restriction enzyme that makes a cut within the DNA at a specific site to generate sticky ends. |
| 2. | They separated DNA base pairs at their terminal ends. |
They separate DNA at any location other than the terminal ends. |
| 3. | They work on single strands of DNA or gaps in double-stranded DNA. | They cut one or both strands of double-stranded DNA. |
उत्तर २
| Feature | Exonuclease | Endonuclease |
| Clevage Site: | Eliminates nucleotides from DNA/RNA ends. | Cuts DNA within the strand at specific sites. |
| Requirement of Free Ends: | Needs free 3' or 5' ends (in one duplex strand). | Requires just one or both strands of the DNA duplex and doesn’t require free ends. |
| Mode of Action: | Progressively removes nucleotides one by one. | Cuts at specific recognition sequences. |
| Example: | DNA polymerase I (has exonuclease activity). | EcoRI, HindIII, BamHI (restriction enzymes). |
संबंधित प्रश्न
Explain with the help of a suitable example the naming of a restriction endonuclease.
Suggest a technique to a researcher who needs to separate fragments of DNA.
Name and describe the technique that helps in separating the DNA fragments formed by the use of restriction endonuclease
Explain briefly:
Restriction enzymes and DNA
Explain the roles of the following with the help of an example each in recombinant DNA technology :
Restriction Enzymes
Answer the following question.
Explain the significance of palindromic nucleotide sequence in the formation of recombinant DNA.
Answer the following question.
Write the use of restriction endonuclease in the formation of recombinant DNA.
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?
A specific recognition sequence identified by endonucleases to make cuts at specific positions within the DNA is ______
'Restriction' in Restriction enzyme refers to ______.
While isolating DNA from bacteria, which of the following enzymes is not required?
The role of DNA ligase in the construction of a recombinant DNA molecule is ______.
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?
CTTAAG
GAATTC
- What are such sequences called? Name the enzyme used that recognizes such nucleotide sequences.
- What is their significance in biotechnology?
Given below is the stepwise schematic representation of the process of electrophoresis. Identify the 'alphabets' representing
- Anode end
- smallest/lightest DNA strand in the matrix
- Agarose gel
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.
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?
