The stain used to visualise separated DNA by gel electrophoresis is?

Appeared in: KPSC Staff Nurse - 2016

Explanation

Ethidium bromide is the standard fluorescent stain used to visualize DNA fragments after separation by agarose gel electrophoresis.
It is an intercalating agent, meaning it fits between the base pairs of the DNA double helix.
When exposed to ultraviolet (UV) light, the DNA-ethidium bromide complex fluoresces, revealing the position of DNA bands as bright orange-red lines.
This method allows for the detection of very small amounts of DNA.

Option B: Haematoxylin is a histological stain used for microscopy, not for visualizing DNA in gels.
Option C: Acetocarmine is a cytogenetic stain for whole chromosomes, not for DNA fragments separated in a gel.
Option D: Feulgen dye is a histochemical stain for DNA within tissue sections, not for DNA in electrophoresis gels.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Staining methods for visualizing DNA in gel electrophoresis as background academic context rather than a clinical decision trigger.
Gel electrophoresis is a fundamental technique in molecular diagnostics. It is used to analyze DNA for genetic testing, such as identifying mutations that cause diseases like cystic fibrosis or sickle cell anemia.
In forensics, this technique is a key part of DNA fingerprinting to identify individuals from biological samples.
In a clinical lab, nurses may be responsible for collecting patient samples (like blood or tissue) that will be analyzed using techniques like gel electrophoresis.

How to Approach the Question

First, identify the core subject of the question: visualizing DNA after gel electrophoresis.
Recognize that this is a factual recall question asking for a specific reagent used in a common laboratory procedure.
Scan the options. Ethidium bromide is the classic and most well-known fluorescent dye for this purpose.
Mentally eliminate the other options by recalling their primary uses: Haematoxylin for general histology, Acetocarmine for chromosomes in mitosis studies, and Feulgen dye for DNA in tissue sections. This confirms Ethidium bromide is the correct choice for DNA in gels.

Concept Tested & Keywords

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E6 Biochemistry U Satyanarayana— Part 2 (pp 421-820 of 840) pp. 387-389, 386-388

Practise the full KPSC Staff Nurse - 2016

Attempt every question from this paper in a timed mock, then review the full solution for each one.