Explain all six required links in protein production
Six required links: gene stays nuclear; mRNA copies information; mRNA is made there and moves to cytoplasm; it passes through ribosomes; amino acids are assembled; mRNA base order determines their order.
Exam scope and assessment notes
Extended only (Supplement) · Biology 0970, 2026–2028. Use the stated specimen features and evidence. Diagrams are schematic. Written practice is self-checked; human subject-teacher review, supervised practical competence and cumulative assessment remain pending. Cambridge states that IGCSE 0970 has the same subject content as IGCSE 0610, with 9–1 grading. This StudyForA pathway maps the 2026–2028 syllabus only. This 9–1 graded qualification is available only in a limited number of administrative zones. Confirm that your centre can enter you for this code and exam series with Cambridge International. Cambridge has published a separate syllabus for 2029. StudyForA has not reconciled that version yet; this page supports exams in 2026, 2027 and 2028 only.
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
Which sequence preserves the source and message route?
What you will learn
- Join nuclear source message movement and ribosome assembly
- Distinguish the information path from the material path
Original teaching model. Counts and records are stipulated; drawings are schematic.
| Feature | Meaning |
|---|---|
| Source and copy | Gene stays nuclear; mRNA is information copy |
| Origin and movement | mRNA made in nucleus → cytoplasm |
| Passage and material | mRNA through ribosome; amino acids assembled |
| Order control | mRNA base sequence → amino-acid sequence |
Join nuclear source message movement and ribosome assembly
Begin with the DNA gene coding for the protein, which remains in the nucleus. Messenger RNA is an information copy made from that gene. mRNA molecules are made in the nucleus and move to the cytoplasm. These first links identify the original source, the copy and its change of location without claiming the original DNA leaves the nucleus.
In the cytoplasmic model, mRNA passes through ribosomes. The ribosome assembles amino acids into protein molecules, and the sequence of bases in mRNA determines the specific amino-acid order. This completes all six listed requirement links: nuclear gene retained, message copy, nuclear origin and movement, ribosome passage, amino-acid assembly and message-order control.
Distinguish the information path from the material path
There are two connected pathways. Information runs from DNA gene to mRNA message to ordered assembly. Material consists of amino acids joined into the product. A missing message route, a non-functioning assembly model or missing required amino-acid material can interrupt the stated sequence, but the result must respect any earlier products or messages explicitly retained in the record.
The original integrated diagram shows the source inside a nuclear boundary, a message crossing to the cytoplasm, and separate incoming amino acids at a ribosome. It is a bounded account rather than detailed transcription or translation chemistry. Explain the six links in connected sentences, with names and locations, before adding any example or evaluating an interruption.
Pause and explain
Which statement completes the order-control link?
Worked example
What is wrong with DNA leaves the nucleus and becomes the protein at a ribosome?
Show the worked solution
- Keep original DNA nuclear and export mRNA information instead.
- Use separate amino-acid material for protein assembly.
Answer The gene remains nuclear; mRNA carries its information to the cytoplasm and ribosomes assemble amino acids using the message order.
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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.
Write the complete six-link protein-production explanation required here.
Give me a hint
Use source, copy, movement, passage, material and order.
Compare my reasoning
- Keep the gene nuclear; make an mRNA information copy there and move it to cytoplasm.
- Pass mRNA through ribosomes; assemble amino acids in the order determined by mRNA bases.
The gene remains in the nucleus. mRNA is its information copy, made in the nucleus and moving to the cytoplasm. mRNA passes through ribosomes, which assemble amino acids into protein in the sequence determined by the mRNA base sequence.
Look for these in your work
- Include all six links
- Keep names and locations correct
Separate the information pathway from the material pathway in that explanation.
Give me a hint
DNA and RNA carry information; amino acids form the product.
Compare my reasoning
- Trace gene information through the mRNA message.
- Trace amino acids into the assembled protein.
Information: nuclear gene → mRNA → ordered ribosome assembly. Material: amino acids → protein chain. DNA and mRNA are not converted into amino-acid material.
Look for these in your work
- Trace information
- Trace material
A stipulated model lacks movement of newly made mRNA but retains an earlier completed protein. Does it prove the earlier protein was never made?
Give me a hint
An interruption applies to the stated later pathway.
Compare my reasoning
- Identify the blocked new-message route.
- Retain the earlier product explicitly supplied.
No. New-message movement is blocked, but the earlier completed protein remains part of the record; the block does not erase its earlier production.
Look for these in your work
- Explain the interruption
- Respect prior evidence
Common mistakes
- Keep the gene, message and product materials separate.
- Include all six listed links rather than only a gene-to-protein arrow.
What can you explain now?
Which statement completes the order-control link?
Compare with the explanation
mRNA base sequence determines the amino-acid sequence
The message specifies the ordered product.
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Make it stick
Explain join nuclear source message movement and ribosome assembly and distinguish the information path from the material path. 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.