Question: 91: Which one of the following statement is not true regarding gel electrophoresis technique?
(1) The presence of chromogenic substrate gives blue coloured DNA bands on the gel.
(2) Bright orange coloured bands of DNA can be observed in the gel when exposed to UV light.
(3) The process of extraction of separated DNA strands from gel is called elution.
(4) The separated DNA fragments are stained by using ethidium bromide.
Answer: Option (1)
Explanation:
Gel electrophoresis is a technique used to separate DNA fragments based on their size by applying an electric field through a gel matrix.
DNA fragments are commonly stained using ethidium bromide,
which intercalates between DNA bases and fluoresces under ultraviolet light,
making DNA bands visible as bright orange bands.
Therefore, the statement that bright orange coloured bands of DNA can be observed under UV light is correct.
After separation, the desired DNA fragment can be cut from the gel and extracted. This extraction process is known as elution.
Chromogenic substrates are not used in gel electrophoresis for DNA visualization.
Hence, the statement that chromogenic substrate gives blue coloured DNA bands is incorrect.
Thus, option (1) is the statement that is not true regarding gel electrophoresis.