Use biological sequence databases
Explain how nucleotide, genome, protein and protein-structure databases support research.
A Level; Cambridge International Biology 9700, 2028–2030. This is curriculum teaching, not medical advice or a claim that a treatment is suitable for an individual. Written responses are self-checked
Before you begin
- DNA stores genetic information; genes can be expressed to produce RNA and protein.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
How can sequence databases help identify a possible gene function?
What you will learn
- Outline benefits of sequence and genome databases
- Explain how protein sequence and structure data support comparison
Build the explanation
Databases collect and organise nucleotide sequences of genes and genomes and amino-acid sequences and structures of proteins. Researchers can search and compare records, identify similar sequences, annotate likely genes or protein features, and share evidence across studies. A database search can support hypotheses about function or evolutionary relationships.
Use the evidence carefully
A database match is evidence, not automatic proof of function. Record quality, annotation, sequence coverage and biological context matter; experimental evidence may still be needed. Databases make information easier to access and compare but do not replace evaluation.
Pause and explain
A short sequence matches one entry at a low-coverage region. What should be checked before annotating the gene?
Worked example
A newly sequenced gene resembles a database entry for an enzyme. What can the similarity support?
Show the worked solution
- Compare aligned sequence evidence.
- Use it as a hypothesis about related function.
Answer The similarity can support a hypothesis that the gene has a related function, but the match alone does not prove its activity.
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Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
A researcher finds a protein sequence similar to a known transporter. What is a cautious inference?
Give me a hint
Identify the relevant material or technology and explain each step.
Compare my reasoning
- Use similarity as evidence.
- Further analysis or experiment may be needed.
The protein may have a related function, but sequence similarity alone does not prove transport activity.
Look for these in your work
- Method identified
- Steps linked to function
Why are protein structure databases useful alongside amino-acid sequences?
Give me a hint
Use the stated example to justify a conclusion.
Compare my reasoning
- Structure provides another level of comparison.
- Shape can inform possible function.
Protein structures help compare folding and possible functional sites, complementing sequence information.
Look for these in your work
- Evidence interpreted
- Limits stated
A short sequence matches one entry at a low-coverage region. What should be checked before annotating the gene?
Give me a hint
Apply the idea to a new application or trade-off.
Compare my reasoning
- Alignment length and quality.
- Other evidence and database annotation.
Check sequence coverage, match quality, annotation reliability and independent evidence before assigning a function.
Look for these in your work
- Application explained
- Claim appropriately bounded
Common mistakes
- Treating a sequence match as experimental proof
- Ignoring how much of the sequence was compared
What can you explain now?
How can sequence databases help identify a possible gene function?
Compare with the explanation
Compare its sequence with annotated records
Similarity can support a hypothesis for further testing.
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Make it stick
What can sequence databases suggest, and what do they not prove alone?
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.