Advertisements
Advertisements
Question
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?
Solution
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.
APPEARS IN
RELATED QUESTIONS
How are 'sticky ends' formed on a DNA strand? Why are they so called?
Mention the difference in the mode of action of exonuclease and endonuclease.
Make a chart (with diagrammatic representation) showing a restriction enzyme, the substrate DNA on which it acts, the site at which it cuts DNA and the product it produces.
Answer the following question.
Write the use of restriction endonuclease in the formation of recombinant DNA.
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?
Which of the following radioisotope is not suitable for DNA labeling based studies?
Restriction enzymes ______.
In agarose gel electrophoresis, DNA molecules are separated on the basis of their ______.
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.
