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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.
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
The total number of nucleotide sequences of DNA that code for a hormone is 1530. The proportion of different bases in the sequence is found to be Adenine = 34%, Guanine = 19%, Cytosine = 23%, Thymine = 19%.
Applying Chargaff’s rule, what conclusion can be drawn?
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 following enzymes catalyse the removal of nucleotides from the ends of DNA?
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 ______.
Which of the following bacteria is not a source of restriction endonuclease?
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.
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?
Carefully observe the given picture. A mixture of DNA with fragments ranging from 200 base pairs to 2500 base pairs was electrophoresed on agarose gel with the following arrangement.
(a) What result will be obtained on staining with ethidium bromide? Explain with reason.
(b) The above setup was modified and a band with 250 base pairs was obtained at X.
What change(s) were made to the previous design to obtain a band at X? Why did the band appear at position X?
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
'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.
What are the protruding and hanging stretches of DNA produced by these restriction enzymes called? Describe their role in the formation of rDNA.
