16. The movement of a single cell was required to be continually monitored during development.
This cell was marked with a reporter gene. To visualize this movement one would use:
A. Phase contrast microscopy
B. Bright field microscopy
C. Fluorescence microscopy
D. Atomic force microscopy
Fluorescence microscopy visualizes reporter gene expression (GFP, RFP) by exciting fluorescent proteins with specific wavelengths, enabling specific cell tracking during development.
Correct Answer
C. Fluorescence microscopy. Reporter genes produce fluorescent proteins detectable only by fluorescence microscopy.
Option Breakdown
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A. Phase contrast microscopy: Incorrect. Enhances contrast via phase shifts for unstained cells; cannot detect fluorescent reporter gene expression.
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B. Bright field microscopy: Incorrect. Standard transmitted light; no fluorescence excitation/filtering capability for reporter visualization.
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C. Fluorescence microscopy: Correct. Uses excitation/emission filters to detect GFP (488/509 nm), RFP, etc., from reporter genes for live cell tracking.
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D. Atomic force microscopy: Incorrect. Nanoscale topography via cantilever scanning; not suitable for live cell movement monitoring.
Fluorescence microscopy cell tracking reporter gene enables real-time monitoring of single cell movements during embryonic development.
GFP/RFP reporter genes express fluorescent proteins visible only under specific excitation light (e.g., 488 nm for GFP). Time-lapse imaging captures migration patterns noninvasively.
Microscopy Technique Comparison
| Technique | Reporter Gene Detection | Live Cell Tracking | GATE Relevance |
|---|---|---|---|
| Fluorescence | Yes (GFP, RFP) | Excellent | Q16 Answer |
| Phase Contrast | No | Good (unstained) | Morphology only |
| Bright Field | No | Poor contrast | Fixed cells |
| Atomic Force | No | Not real-time | Surface only |
Key Advantage: Specific labeling distinguishes tracked cell from neighbors in dense tissues.
Applications in Development
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Zebrafish gastrulation: GFP-labeled neural crest migration
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Drosophila: RFP neuroblasts during neurogenesis
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Mouse ESC: Fate mapping with multicolor reporters
Exam Memory: Reporter = Fluorescence. Phase/Bright field see all cells; fluorescence sees only marked cells.
