Explain how mitotic daughters can specialise while retaining shared genes
Normal mitosis can preserve shared genes while a daughter later specialises through different protein expression and structure. Non-expression is not deletion; the diagram is a supplied nucleated-cell model.
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 chromosomes, genes, chromosome sets, selective gene expression and the distinction between a nucleus and a whole cell.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
How can a daughter specialise while retaining the supplied shared genes?
What you will learn
- Connect shared genes with different protein use
- Distinguish division from differentiation
Original teaching model. Counts and records are stipulated; drawings are schematic.
| Feature | Meaning |
|---|---|
| Mitotic contribution | Copy and distribute the genetic complement |
| Later specialisation | Develop structures and proteins for a function |
| Shared genes | Different expression can coexist with matching DNA |
| Limit | A cell drawing does not prove a changed chromosome set |
Connect shared genes with different protein use
A stem-cell daughter can become specialised for a particular function after mitotic production. Specialisation involves developing an appropriate structure and protein-expression pattern. For example, a supplied secretory-cell model produces the proteins needed for its stated secretion, whereas another daughter may retain the unspecialised state. These later differences do not contradict their shared genetic information.
The chromosome-and-expression pathway explained that most body cells contain the same genes but use different subsets. Apply that idea here: a daughter can express genes needed for its function while other genes are not expressed in that state. Lack of expression is not the same as deletion of the gene, and mitosis is not a process that intentionally gives each daughter only the genes for its future role.
Distinguish division from differentiation
This explanation refers to the stated nucleated daughter-cell model. It is not a claim that every mature body cell keeps a nucleus forever; mature mammalian red blood cells are a familiar exception. Nor does the stem-cell definition imply that every mature specialised cell can reverse its state and freely become any other type. The question's population and observations set the supported possibilities.
Use two linked explanations without collapsing them. Mitosis preserves and distributes the copied genetic complement; subsequent specialisation changes how a daughter functions using its information. A drawing of different shapes or colours can illustrate those states but does not itself prove a DNA sequence, a missing gene or a universal capacity to differentiate.
Sources for this lesson
Pause and explain
Which statement keeps the two mechanisms distinct?
Worked example
Two matching nucleated daughters later express different proteins. Does that require different gene complements?
Show the worked solution
- Identify the shared genes.
- Explain different selective expression.
Answer No. Different protein use can follow selective gene expression while the supplied gene complements match.
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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.
Explain how a mitotic daughter can become a specialised secretory cell in the supplied model.
Give me a hint
Connect shared DNA with required proteins.
Compare my reasoning
- Retain the copied gene complement.
- Express the genes and proteins needed for the stated function.
The daughter retains the supplied genetic information but develops the structure and protein-expression pattern needed for secretion through subsequent specialisation.
Look for these in your work
- Preserve shared information
- Explain the later functional change
A gene is not expressed in a specialised daughter. Explain why this does not establish deletion.
Give me a hint
Separate presence from use.
Compare my reasoning
- Identify non-expression as a cell-state observation.
- Retain the supplied DNA record unless evidence changes it.
Non-expression means the gene is not being used in that stated context; it does not prove the gene has been removed from the DNA.
Look for these in your work
- Distinguish presence and expression
- Use the stated evidence
Two descendants have different drawn shapes but no DNA record is supplied. Can the shapes prove that mitosis gave them different chromosome sets?
Give me a hint
Shapes are not chromosome-set evidence.
Compare my reasoning
- Identify the observed appearance difference.
- State the missing genetic-complement evidence.
No. Different shapes can illustrate specialisation but do not establish different chromosome sets or deliberate unequal genetic distribution by mitosis.
Look for these in your work
- Acknowledge the appearance
- Avoid unsupported genetic inference
Common mistakes
- Non-expression is not gene deletion.
- Specialisation and mitotic nuclear division are different events.
What can you explain now?
Which statement keeps the two mechanisms distinct?
Compare with the explanation
Mitosis preserves copied information; later specialisation changes cell function
The linked events explain different aspects.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Without your notes, connect shared genes with different protein use and distinguish division from differentiation. Distinguish nuclear division, chromosome copies and completed daughter cells 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.