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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?
Name the enzymes that are used for the isolation of DNA from bacterial and fungal cells for recombinant DNA technology.
Do eukaryotic cells have restriction endonucleases? Justify your answer.
Explain the roles of the following with the help of an example each in recombinant DNA technology :
Restriction Enzymes
Give a reason why :
Single cloning site is preferred in a vector.
Restriction enzymes ______.
There is a restriction endonudease called as EcoRI. What does co part in it stands for?
Molecular scissors, which cut DNA at specific site is ______.
'Restriction' in restriction enzyme refers to
DNA strands on a gel stained with ethidium bromide when viewed under UV radiation, appear as ______
Which of the given statements is correct in the context of visualizing DNA molecules separated by agarose gel electrophoresis?
In agarose gel electrophoresis, DNA molecules are separated on the basis of their ______.
Which of the following bacteria is not a source of restriction endonuclease?
Which of the following statements does not hold true for restriction enzyme?
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.
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 are the protruding and hanging stretches of DNA produced by these restriction enzymes called? Describe their role in the formation of rDNA.
Identify the activity of endonuclease and exonuclease in the given image.
