Cell signalling: a receptor selects the response
הוצג| English | משמעות |
|---|---|
| receptor/rɪˈseptə/ | קולט |
| signal transduction/ˈsɪɡnl trænsˈdʌkʃn/ | העברת אותות |
What would explain this observation?
- Two cell types encounter the same signal but respond differently. Their receptors 受体 and internal pathways determine what follows.
Build the model
- A signalling molecule binds a compatible receptor.
- Receptor activation can initiate signal transduction 信号转导 through intracellular molecules.
- The resulting response may change enzyme activity, transport or gene expression.
- A signal need not enter the cell to cause an effect.
- receptor: A molecule that binds a compatible signal.
- signal transduction: Conversion of signal reception into intracellular changes.
Why can one signal produce different effects in two cell types?
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
A signal's effect is decided by the receiving cell: different receptors or different internal pathways turn the same signal into different responses. The signal molecule itself carries no instruction beyond binding.
Match each technical term to its precise meaning.
רמת קושי 2/5 · 140 מטבעות + בונוס קטן בהשלמה הראשונה היום
Use the definitions to distinguish related quantities and processes.
Choose evidence that can test it
- Distinguish signal reception, transduction and response.
- Amplification can allow a small extracellular change to produce a larger intracellular effect.
- Different receptors or pathways can give different responses to one signal.
In the lab: Use an attributed dataset comparing signal concentration and response. Include an untreated control and, where supplied, receptor-blocking evidence. Do not infer the whole pathway from a concentration-response graph alone.
Which two habits make the investigation or model in this case more defensible?
רמת קושי 2/5 · 140 מטבעות + בונוס קטן בהשלמה הראשונה היום
Stating the conditions and assumptions lets others repeat the work exactly, and recording the supporting evidence lets them check the conclusion. Hiding disagreeing results removes the evidence that could challenge a wrong conclusion, and one measurement can never establish a wider claim.
Work from known quantities
- Known: response increases from 20 to 80 units.
- Fold change = 80/20 = 4.
- Percentage increase = (80−20)/20 × 100 = 300%.
- A fourfold final value is not a 400% increase.
Your turn: Response rises from 10 to 50 units. Calculate the fold change.
Response rises from 10 to 50 units. Calculate the fold change.
רמת קושי 2/5 · 140 מטבעות + בונוס קטן בהשלמה הראשונה היום
The result is 5 . Known: response rises from 10 to 50 units. Use fold change = final / initial. Fold change = 50/10 = 5. Note this is a fivefold final value, which corresponds to a 400% increase, not a 500% one.
Check the conclusion and its limits
- A receptor is not interchangeable with every signalling molecule.
- Greater signal concentration does not imply unlimited response once the system saturates.
Not true: Fourfold final response means a 400% increase from baseline. A fold change is a ratio of final to initial; a percentage increase is the change relative to the initial value. A fourfold final value means a 300% increase, so "fourfold" and "400%" are not interchangeable.
- A signalling molecule binds a compatible receptor.
- Distinguish signal reception, transduction and response.
- Watch for: A receptor is not interchangeable with every signalling molecule.
Write from a threefold rise
- A response rises from 12 units to 36 units.
- Find the fold change and the percentage increase. A threefold value is not a 300 percent increase.
Fourfold final response means a 400% increase from baseline.
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
A fold change is a ratio of final to initial; a percentage increase is the change relative to the initial value. A fourfold final value means a 300% increase, so "fourfold" and "400%" are not interchangeable.
A molecule that binds a compatible signal: write the technical term.
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
receptor means A molecule that binds a compatible signal.
A response rises from 12 units to 36 units. What are the fold change and the percentage increase?
36 divided by 12 is 3. The added 24 is twice the start, so the percentage increase is 200 percent.
What is the fold change?
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
36 divided by 12 is 3, and the percentage increase is 200 percent.