Methods in Molecular Biology: From Classic Assays to Multi-Omics and Single-Cell Perturbation
Experimental platforms
Core methodological families
Molecular biology relies on a layered toolkit: cloning, PCR, blotting, immunoprecipitation, microscopy, sequencing, mass spectrometry, and computational inference. Modern research increasingly combines perturbation with readout, for example CRISPR screens coupled to single-cell RNA-seq, ATAC-seq, spatial transcriptomics, or proteomics.
Method comparison
| Method | Primary readout |
|---|---|
| ChIP-seq | Protein-DNA occupancy |
| ATAC-seq | Chromatin accessibility |
| RNA-seq | Transcript abundance |
| Ribo-seq | Translating ribosomes |
| Mass spectrometry proteomics | Protein abundance and modification |
| Single-cell RNA-seq | Cell-to-cell transcriptional heterogeneity |
Causal perturbation
A central advance is the shift from observational to perturbational biology. Perturbation assays allow one to ask whether a factor is necessary or sufficient for a phenotype. However, interpreting outcomes requires careful control of guide efficiency, dosage, cell-cycle state, and off-target effects.
Best practice
The strongest conclusions usually come from orthogonal validation: independent perturbations, rescue experiments, and at least one mechanistically distinct assay.
Which assay directly reports chromatin accessibility?
ATAC-seq uses transposase insertion to infer accessible regions.
Correct answer: ATAC-seq
What is the main advantage of perturbation-based screening over pure correlation studies?
Perturbation can reveal necessity and, with the right design, sufficiency.
Correct answer: It provides stronger causal evidence
Which readout is most appropriate for measuring actively translated mRNAs?
Ribosome profiling captures ribosome-protected fragments and thus translational engagement.
Correct answer: Ribo-seq
Why are orthogonal validation experiments necessary?
Independent evidence increases confidence in the biological conclusion.
Correct answer: To rule out assay-specific artifacts and off-target explanations
Frontier trend
Multi-modal single-cell assays are merging transcriptomic, epigenomic, proteomic, and spatial information into unified cell-state maps.