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प्रश्न
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?
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उत्तर
The reasons are as follows:
- DNA sample that was loaded on the gel may have got contaminated with nuclease (exo-or endo-or both) and completely degraded.
- Electrodes were put in opposite orientation in the gel assembly that is anode towards the wells (where DNA sample is loaded). Since DNA molecules are negatively charged, they move towards anode and hence move out of the gel instead of moving into the matrix of gel.
- Ethidium bromide was not added at all or was not added in sufficient concentration and DNA was not visible.
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संबंधित प्रश्न
How are 'sticky ends' formed on a DNA strand? Why are they so called?
How does restriction endonuclease function?
Explain the roles of the following with the help of an example each in recombinant DNA technology :
Restriction Enzymes
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?
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 enzymes catalyse the removal of nucleotides from the ends of DNA?
The role of DNA ligase in the construction of a recombinant DNA molecule is ______.
Which of the following bacteria is not a source of restriction endonuclease?
CTTAAG
GAATTC
- What are such sequences called? Name the enzyme used that recognizes such nucleotide sequences.
- What is their significance in biotechnology?
State the principle involved in separation of DNA fragments using gel electrophoresis.
How are DNA fragments visualised once they are separated by gel electrophoresis?
In the standard nomenclature convention for restriction endonucleases, what do the second and third letters signify?
Why is it mandatory to cut both the vector DNA and the foreign source DNA with the exact same restriction enzyme when constructing recombinant DNA?
During agarose gel electrophoresis, why do DNA fragments migrate toward the anode (positive electrode)?
What is the origin of agarose, the matrix most commonly used in gel electrophoresis?
How are separated DNA bands visualized following agarose gel electrophoresis?
What is the process called when desired, separated DNA bands are physically cut out from the agarose gel and extracted from the gel piece?
Why are Type II restriction endonucleases the primary class of restriction enzymes used in genetic manipulation?
