Bioinformatics and omics

Sequence Alignment interview questions

Biological sequence similarity, algorithms and interpretation.

6 questions, each with a worked answer

What is the difference between local and global sequence alignment? Fundamentals Concept
How should E-values be interpreted in database sequence searches? Fundamentals Interpretation
How do gap penalties change a protein alignment? Intermediate Scenario
What is the difference between sequence identity and sequence similarity? Intermediate Concept
When does database size affect the significance of a BLAST hit? Advanced Scenario
Why does a conserved domain not establish that two proteins share the same biological function? Advanced Scenario

About Sequence Alignment

Sequence alignment arranges DNA, RNA or protein sequences to show where they match, differ or have gaps, as evidence of shared function or ancestry. Algorithms range from exact dynamic programming to fast heuristic search tools such as BLAST and short-read aligners. Scoring matrices, gap penalties and statistical scores like E-values determine what a hit means.

It is the starting point for annotation, variant calling, primer design and much of bioinformatics.

Fundamentals: 2
Intermediate: 2
Advanced: 2

What these questions test

Interpret alignments: Assess sequence matches under appropriate scoring and biological context.

References

NCBI Bookshelf. National Library of Medicine. ncbi.nlm.nih.gov/books.
biopython.org/docs/latest/Tutorial/chapter_pairwise.html.
blast.ncbi.nlm.nih.gov/Blast.cgi?CMD=Web&DOC_TYPE=FAQ&PAGE_TYPE=BlastDocs.
ebi.ac.uk/training/online/courses/guide-to-sequence-analysis-tools/sequence-alignment/multiple-sequence-alignment.

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.