47. Gamma phosphate labelled ATP molecule was used to label a DNA fragment using the nick translation
protocol. This would result in:
1. Labelling at 5′end
2. Labelling at 3′end
3. Labelling at both 3′and 5′ends
4. No labelling of DNA
The Nick Translation Protocol and Gamma Phosphate-Labeled ATP
Nick translation is a molecular biology technique used for labeling DNA fragments. This method involves introducing single-strand breaks (nicks) in DNA and incorporating labeled nucleotides during DNA repair synthesis. It’s commonly used for labeling DNA for various applications, such as hybridization and sequencing.
One key element in the nick translation protocol is the use of gamma phosphate-labeled ATP, which helps in the incorporation of radioactive or fluorescent markers into the DNA. Understanding how this labeling works is crucial for those performing DNA labeling experiments.
What is Gamma Phosphate-Labeled ATP?
In the nick translation process, ATP molecules with a labeled gamma phosphate (often radioactively labeled) are used. The gamma phosphate is the terminal phosphate group in the ATP molecule, and its incorporation into the DNA strand allows for labeling.
When a DNA fragment undergoes nick translation, an endonuclease creates nicks in the DNA, and a DNA polymerase fills in the gaps using nucleotides. The labeled ATP can be incorporated at the nick sites during this process.
Outcome of Gamma Phosphate Labeling in Nick Translation
The gamma phosphate-labeled ATP is incorporated into the newly synthesized DNA strand during the filling of the nick. Since the nick translation process involves both 3′ and 5′ end processing, labeling occurs at the newly synthesized DNA, which can include both 3′ and 5′ ends of the fragment.
Key Points:
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Gamma phosphate refers to the terminal phosphate group in the ATP molecule.
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Nick translation involves DNA polymerase adding nucleotides at nicks, resulting in the labeling of the DNA strand at both 3′ and 5′ ends.
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The radioactive or fluorescent marker is incorporated into the newly synthesized strand as the DNA polymerase fills the gap.
The Correct Answer:
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Answer: 3. Labeling at both 3′ and 5′ ends
Conclusion
The use of gamma phosphate-labeled ATP in the nick translation protocol results in labeling at both the 3′ and 5′ ends of the DNA fragment. This process is crucial for applications in DNA analysis, where specific labeling of DNA regions is necessary for further experiments. By understanding the mechanics of nick translation, researchers can effectively utilize this technique in their molecular biology workflows.
