Q1.Which of the following technique is used for tracing change in intracellular location of proteins and metabolites.
(A) Chromatography
(B) DNA foot printing
(C) DNA end labelling
(D) Pulse-chase experiment
Answer: (D) Pulse-chase experiment
The pulse-chase experiment tracks dynamic changes in the intracellular location of proteins and metabolites over time.
Option Breakdown
Chromatography (A)
Chromatography separates mixture components by properties like size or charge for analysis.
It identifies proteins or metabolites but does not trace their movement or location changes inside cells.
DNA Footprinting (B)
DNA footprinting detects protein-DNA binding sites by protecting DNA from nuclease digestion.
This technique maps interactions on DNA, not intracellular shifts of proteins or metabolites.
DNA End Labelling (C)
DNA end labelling adds radioactive or fluorescent tags to DNA ends for detection in sequencing or binding studies.
It prepares DNA for analysis but fails to monitor location changes of proteins or metabolites.
Pulse-Chase Experiment (D)
Cells receive a short “pulse” of labelled precursors (e.g., radioactive amino acids), then unlabelled “chase” to follow labelled molecules.
This reveals synthesis, trafficking, processing, and degradation paths within cellular compartments.
The pulse-chase experiment intracellular location technique revolutionized how researchers track proteins and metabolites inside cells. This method pulses cells with labelled molecules, then chases with unlabelled ones to monitor dynamic shifts.
What is Pulse-Chase Experiment?
Autoradiography or microscopy then visualizes labelled molecules moving from ER to Golgi, plasma membrane, or secretion.
It quantifies half-life, trafficking rates, and processing in live systems.
This diagram shows DNA footprinting (option B), highlighting its focus on static binding—not dynamic tracking like pulse-chase.
Why Not Other Techniques?
Chromatography excels at separation but ignores spatial dynamics.
DNA footprinting and end labelling target DNA interactions, unsuitable for broad protein/metabolite localization.
Applications in Research
Pulse-chase tracks MHC protein biosynthesis, lipid turnover, and mRNA processing.
Modern versions use stable isotopes with mass spectrometry for safer, high-precision analysis.
This approach remains essential for cell biology studies, confirming D as the correct choice.
