Trace mRNA movement from nucleus to cytoplasm
The gene stays nuclear while its mRNA copy moves from nucleus to cytoplasm. A message-route interruption limits those messages’ ribosome access without deleting the original DNA.
Section B16.1 · Chromosomes and genes
Exam scope and assessment notes
Mapped to the named 0973 section using teaching from the corresponding single-science course. A 0973-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. This qualification reports two grades on the 9–1 scale; confirm the entry route for your zone and exam series.
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 movement is required before the depicted cytoplasmic assembly?
What you will learn
- Locate message production and later ribosome access
- Keep the original gene and exported message distinct
Original teaching model. Counts and records are stipulated; drawings are schematic.
| Feature | Meaning |
|---|---|
| Original gene | Remains in nucleus |
| Message origin | mRNA made in nucleus |
| Message route | Moves to cytoplasm |
| Access link | Can reach the depicted ribosome |
Locate message production and later ribosome access
The required sequence places mRNA production in the nucleus and later protein assembly in the cytoplasm. mRNA molecules move from the nucleus to the cytoplasm, carrying the coding information. The source gene remains in the nucleus. This location change concerns the message molecule rather than the entire gene or the finished protein.
A ribosome can use the message after it reaches the relevant cytoplasmic setting. The classroom diagram draws a boundary between nucleus and cytoplasm and an arrow for mRNA movement. It is a location model, not a detailed diagram of nuclear-pore chemistry or a claim that every cytoplasmic protein has an identical final destination.
Keep the original gene and exported message distinct
A hypothetical interruption that keeps all messages inside the nucleus prevents those messages reaching the depicted cytoplasmic ribosome. This predicts a limitation on the stated pathway, not loss of the DNA gene. If a record says some messages already reached the cytoplasm, do not erase that information or conclude every assembly event instantly stopped.
The original route cards ask which molecule is where at each stage. Source DNA stays nuclear; newly made mRNA starts nuclear and later appears in the cytoplasm; the ribosome assembles amino acids using the message. Use these locations to explain an interruption without inventing a diagnosis or a mechanism beyond the supplied condition.
Sources for this lesson
Pause and explain
What is blocked if every new message remains nuclear?
Worked example
A model retains every newly made message in the nucleus. What route is blocked?
Show the worked solution
- Identify mRNA movement to the cytoplasm.
- Separate that from the gene remaining nuclear.
Answer The blocked route is mRNA movement from nucleus to cytoplasm, so those messages cannot reach the depicted cytoplasmic ribosome.
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.
Trace the locations of the original gene and its mRNA message.
Give me a hint
Give source location and message route separately.
Compare my reasoning
- Keep the gene in the nucleus.
- Move mRNA from nucleus to cytoplasm.
The gene remains nuclear; mRNA is made in the nucleus and then moves to the cytoplasm.
Look for these in your work
- Keep source location
- Give both message locations
In a stipulated model all new mRNA is retained in the nucleus. Explain the effect on those messages’ access to a cytoplasmic ribosome.
Give me a hint
Follow the blocked movement.
Compare my reasoning
- Identify messages lacking cytoplasmic entry.
- Connect that with lack of access to the depicted ribosome.
Those messages do not reach the cytoplasm, so they cannot pass through the depicted cytoplasmic ribosome in this model.
Look for these in your work
- Name blocked movement
- Explain the access effect
A record also states two messages reached the cytoplasm before the block. Does the block prove they instantly vanish?
Give me a hint
Use every stated condition.
Compare my reasoning
- Retain the two pre-existing cytoplasmic messages.
- Reject an unprovided removal event.
No. The record retains two messages already in the cytoplasm; blocking new movement does not itself prove those existing messages vanish.
Look for these in your work
- Respect prior messages
- Reject an added event
Common mistakes
- mRNA moves, while the source DNA stays nuclear.
- An interruption prediction must respect messages already supplied in the record.
What can you explain now?
What is blocked if every new message remains nuclear?
Compare with the explanation
Those messages reaching the cytoplasmic ribosome
The specified message route is unavailable.
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Make it stick
Explain locate message production and later ribosome access and keep the original gene and exported message distinct. 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.