Molecular and cell biology

Molecular Biology interview questions

DNA, RNA, gene regulation and molecular mechanisms used in experimental biology.

9 questions, each with a worked answer

How do transcription and translation differ? Fundamentals Concept
How would you verify that a plasmid contains the intended insert? Intermediate Practical
When can transcript abundance and protein activity move in opposite directions? Intermediate Concept
How would you separate transcriptional regulation from RNA stability effects? Intermediate Scenario
What controls establish that a gene-editing experiment worked as intended? Advanced Scenario
How would you investigate inconsistent transfection efficiency across cell lines? Advanced Scenario
How would you distinguish a transcriptional change from altered RNA stability after a drug treatment? Intermediate Troubleshooting
A CRISPR knockout shows no phenotype despite strong genotyping evidence. What explanations would you test? Intermediate Scenario
Design a rescue experiment to determine whether a phenotype is caused by the intended genetic perturbation. Advanced Practical

About Molecular Biology

Molecular biology studies how DNA, RNA and proteins carry and use genetic information inside a cell. It covers replication, transcription, translation and the controls that decide when and how strongly a gene is expressed. In the lab it is also a toolkit: cloning, PCR, sequencing, blotting and gene editing all come from it.

Almost every bench role in biotech draws on it, because most experiments end in a claim about a molecule.

Fundamentals: 1
Intermediate: 5
Advanced: 3

What these questions test

Interpret molecular assays: Read molecular assay controls and limitations before making biological claims.

References

NCBI Bookshelf. National Library of Medicine. ncbi.nlm.nih.gov/books.
nature.com/articles/s41576-020-0258-4.
help.addgene.org/hc/en-us/articles/206135535-What-plasmid-quality-control-QC-does-Addgene-perform.
pubmed.ncbi.nlm.nih.gov/31768977.
addgene.org/guides/crispr/plan-your-experiment.
addgene.org/protocols/transfection.
pmc.ncbi.nlm.nih.gov/articles/PMC6858503.
pmc.ncbi.nlm.nih.gov/articles/PMC10823772.

Practice material written by TheBench.Bio and checked against the references above, reviewed October 23, 2026. Written to practise with, not collected from real interviews.