Specialized cells: structure linked to function
הוצג| English | משמעות |
|---|---|
| differentiation/ˌdɪfəˌrenʃɪˈeɪʃn/ | התמיינות |
| gene expression/dʒiːn ekˈspreʃn/ | ביטוי גנטי |
What would explain this observation?
- A root-hair cell and a red blood cell have different shapes because their functions impose different demands.
Build the model
- Differentiation 分化 produces specialized cells through different patterns of gene expression 基因表达.
- A root-hair extension increases exchange area.
- A mammalian red blood cell lacks a nucleus at maturity and contains haemoglobin; this is a specific adaptation, not a rule for all animal cells.
- differentiation: Development of specialized cell structure and function.
- gene expression: Use of genetic information to produce a functional product.
What best explains many differences between specialized cells?
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
Specialized cells share the same genome but express different gene sets, producing different proteins and therefore different structures. The genetic code is universal, and all these cells descend from the same zygote.
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
- Link a named feature to a mechanism and then to the function.
- Increased area can support exchange, but membrane proteins, gradients and metabolic demand also matter.
- Stem cells retain different degrees of developmental potential.
In the lab: Compare scaled drawings of named cells. Label the structure, state the function and explain the causal link. Use tissue-specific examples rather than saying every specialized cell has every adaptation.
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: a spherical model cell has radius 2 units.
- Surface area/volume = 3/r = 1.5 per unit.
- A radius of 4 gives 0.75 per unit.
- Doubling radius halves this ratio, even though total area increases.
Your turn: For a sphere, surface area/volume = 3/r. Find this ratio when r = 6 units.
For a sphere, surface area/volume = 3/r. Find this ratio when r = 6 units.
רמת קושי 2/5 · 140 מטבעות + בונוס קטן בהשלמה הראשונה היום
The result is 0.5 per unit. Known: for a sphere, surface area / volume = 3/r; r = 6 units. Ratio = 3/6 = 0.5 per unit. Larger radius means a smaller surface-area-to-volume ratio, even though the total surface grows.
Check the conclusion and its limits
- Specialization does not usually require a cell to lose most of its genes.
- The spherical calculation models geometry; it does not describe every actual cell shape.
Not true: All mature animal cells lack a nucleus. Most mature animal cells keep their full genome and nucleus; only a few exceptions, such as mammalian red blood cells, lose the nucleus. Specialization comes from gene expression, not gene loss.
- Differentiation produces specialized cells through different patterns of gene expression.
- Link a named feature to a mechanism and then to the function.
- Watch for: specialization does not usually require a cell to lose most of its genes.
Write from a surface-to-volume ratio of 0.30
- A spherical model cell has radius 10 units. Use surface area over volume = 3 over r.
- Find the ratio. Doubling the radius halves this ratio.
Most mature animal cells keep their full genome and nucleus; only a few exceptions, such as mammalian red blood cells, lose the nucleus.
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
True. Most mature animal cells keep their full genome and nucleus; only a few exceptions, such as mammalian red blood cells, lose the nucleus. Specialization comes from gene expression, not gene loss.
Development of specialized cell structure and function: write the technical term.
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
differentiation means Development of specialized cell structure and function.
For a sphere, surface area over volume is 3 over r. What is the ratio when r is 10 units, and what happens to the ratio if the radius doubles?
3 over 10 is 0.30. A radius of 20 would give 0.15.
What is the surface-to-volume ratio at radius 10?
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
3 divided by 10 is 0.30 per unit. Other options — 0.50 per unit (the earlier calculation's result for radius 6); 0.75 per unit (the lesson example's result for radius 4).