Link gene base order with the order of amino acids in a protein
Gene base order determines amino-acid order. Supplied short chains can share the same amino acids but have different sequences; the schematic does not decode an absent gene record.
Mapped to the named 0654 section using teaching from the corresponding single-science course. A 0654-specific review of every Core and Supplement objective is still in progress. Written practice is self-checked; it does not demonstrate supervised laboratory competence or award an official Cambridge grade.
Before you begin
- Recall the nucleus, DNA base pairing, gametes, fertilisation, enzymes, membrane carriers and chemical synapses.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
What does gene base order determine in this requirement?
What you will learn
- Connect an ordered information sequence with an ordered product
- Avoid predicting an exact protein without a supplied key
Original teaching model. Counts and records are stipulated; drawings are schematic.
| Feature | Meaning |
|---|---|
| Gene information | Sequence of DNA bases |
| Product order | Sequence of amino acids |
| Given chain A | Alanine → lysine → proline |
| Given chain B | Alanine → proline → lysine |
Connect an ordered information sequence with an ordered product
The sequence of bases in a protein-coding gene determines the sequence of amino acids used to make its protein. Sequence means order, not just the number or total amount of the building blocks. Two records can contain the same kinds of items but in different orders. The gene stores the information, while amino acids are the material assembled into the product.
An original teaching record stipulates protein sequence A as alanine–lysine–proline and sequence B as alanine–proline–lysine. These chains contain the same three named amino acids but place the second and third in different positions. The record illustrates why order matters. It does not supply a complete gene base sequence or require learners to reconstruct one using an absent genetic-code table.
Avoid predicting an exact protein without a supplied key
A change in gene information can change an amino-acid sequence, but do not claim that every possible base change must always change a protein. The syllabus requirement establishes the information relationship without requiring the details of nucleotide structure or the full genetic code. Keep the given sequence and outcome evidence rather than inventing a specific molecular effect from a coloured DNA drawing.
The original model separates a DNA base-order label from a supplied amino-acid chain. The arrow denotes information determining assembly order, not DNA turning into amino acids. A particular protein shape or function needs further evidence; the next lesson explains how different amino-acid sequences can affect shape without presenting these short chains as complete natural proteins.
Sources for this lesson
Pause and explain
Two chains have the same amino acids in different orders. Which statement is correct?
Worked example
Do alanine–lysine–proline and alanine–proline–lysine have the same sequence?
Show the worked solution
- Compare the order rather than the item totals.
- Locate the changed second and third positions.
Answer No. They contain the same three named amino acids but differ in order at positions two and three.
Try a topic test
Choose Easy, Normal or Difficult. Save your answers and open worked review after finishing.
Test this topic →From guided practice to a new situation
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.
State the relationship between gene bases and amino-acid sequence.
Give me a hint
Use order on both sides of the relationship.
Compare my reasoning
- Identify the gene base sequence.
- Connect it with amino-acid assembly order.
The sequence of bases in the gene determines the sequence of amino acids used to make its protein.
Look for these in your work
- Name base sequence
- Name amino-acid sequence
Compare the supplied chains alanine–lysine–proline and alanine–proline–lysine.
Give me a hint
Check each position.
Compare my reasoning
- Retain alanine at position one.
- Identify lysine and proline exchanging the next positions.
Both start with alanine, but positions two and three differ: lysine/proline versus proline/lysine, so the sequences are different.
Look for these in your work
- Compare positions
- Distinguish order from totals
A DNA drawing has coloured bases but no sequence key or product record. Can it establish an exact amino-acid chain?
Give me a hint
A general relationship does not supply missing sequence data.
Compare my reasoning
- Identify the missing base-order and mapping evidence.
- Reject an exact reconstruction from colour alone.
No. The drawing illustrates information but does not supply the exact sequence and required mapping evidence for an exact amino-acid chain.
Look for these in your work
- State what is missing
- Reject invented detail
Common mistakes
- Sequence means order, not only composition.
- Do not invent an exact DNA sequence from an amino-acid outline.
What can you explain now?
Two chains have the same amino acids in different orders. Which statement is correct?
Compare with the explanation
Their sequences differ
Order is part of the sequence.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Explain connect an ordered information sequence with an ordered product and avoid predicting an exact protein without a supplied key. Use the stated cell, chromosome sets and information pathway before opening the solutions.
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.