Q17
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A comet assay is a technique used to determine the amount of double-strand breakages in DNA (DNA damage) in cells. A cell is exposed to a mutagen that damages the DNA causing double-strand breaks. The nucleus of the cell is placed on a microscope slide coated with an agarose gel. An electric current is applied to the gel that causes DNA to move (electrophoresis), and the DNA is stained with a fluorescent dye. When viewed using a microscope, undamaged DNA from the nucleus appears as a round shape (the head), and the fragments of damaged DNA with double strand breaks extend out from the head (the tail). The length of the tail corresponds to the amount of the damage in the DNA. Figure 1: Comet Assay
The following events occur after DNA is subjected to radiation. The events are listed in no specific order. W: Mutation X: Change in cell activity Y: Change in protein structure Z: Change in polypeptide sequence What is the correct sequence of steps?
A. W, X, Y, Z
B. Z, X, W, Y
C. Z, Y, X, W
D. W, Z, Y, X
Syllabus alignment
- MutationAssess the significance of coding and non-coding DNA in mutation.
- MutationCompare causes, processes and effects of point and chromosomal mutations.