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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
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.
Name the enzymes that are used for the isolation of DNA from bacterial and fungal cells for recombinant DNA technology.
How does a restriction nuclease function? Explain
Explain briefly:
Restriction enzymes and DNA
Answer the following question.
Explain the significance of palindromic nucleotide sequence in the formation of recombinant DNA.
Give a reason why :
Single cloning site is preferred in a vector.
There is a restriction endonudease called as EcoRI. What does co part in it stands for?
DNA strands on a gel stained with ethidium bromide when viewed under UV radiation, appear as ______
In agarose gel electrophoresis, DNA molecules are separated on the basis of their ______.
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?
A mixture of fragmented DNA was electrophoresed in an agarose gel. After staining the gel with ethidium bromide, no DNA bands were observed. What could be the reason?
CTTAAG
GAATTC
- What are such sequences called? Name the enzyme used that recognizes such nucleotide sequences.
- What is their significance in biotechnology?
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.
'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.
State the principle involved in separation of DNA fragments using gel electrophoresis.
Identify the activity of endonuclease and exonuclease in the given image.
