Lesson 2 of 5 / Cell structure and organisation
Plant cells and animal cells
Which differences are useful evidence?
In this lesson: Compare typical cells without assuming that every cell looks the same.
About 4 min
The key ideaTypical plant and animal cells share a membrane, cytoplasm and nucleus. A cellulose wall and a large permanent vacuole distinguish a typical mature plant cell.
Compare structures, not just the overall shape. Switch between a photosynthetic plant cell, an onion bulb cell and a typical animal cell.
Explore the idea
What changes between these cells?
The photosynthetic leaf cell has a wall, a large sap-filled vacuole and chloroplasts. Its membrane, cytoplasm and nucleus are shared with typical animal cells.
Original schematic, not to scale. The blue region is a vacuole; purple marks the nucleus. Plant cells also contain mitochondria and ribosomes, omitted here to focus on this comparison.
Explanation
Plant and animal cells carry out many of the same essential activities. Typical cells of both types have a membrane, cytoplasm and nucleus. Both also contain mitochondria and ribosomes, although these smaller structures are not normally distinguishable in a school light microscope.
A typical mature plant cell has a cellulose cell wall and a large permanent, sap-filled vacuole. Photosynthetic plant cells contain chloroplasts. Typical animal cells have no cellulose wall or chloroplasts and may contain small temporary vacuoles.
The word typical matters. An onion bulb storage cell is a plant cell but normally has no chloroplasts. A mature mammalian red blood cell is an animal cell but has no nucleus. These cells have structures suited to particular jobs.
When comparing cells, give matching statements: a plant cell has a cell wall whereas an animal cell does not. A rectangular outline alone is weak evidence. Preparation, viewing angle and the particular cell type can all change the shape seen.
Step by step
- 1
Start with shared features
Name structures found in both typical cells, such as the membrane, cytoplasm and nucleus.
- 2
Compare the same feature
For example: a typical mature plant cell has a large permanent vacuole; an animal cell may have small temporary ones.
- 3
Check the context
A root hair cell or onion bulb cell does not need chloroplasts for its function.
Worked example
An unfamiliar cell
A cell has a nucleus, a cellulose wall and a large sap-filled vacuole, but no chloroplasts. A student calls it an animal cell. Evaluate the claim.
One way to explain it
The claim is not supported. The cellulose wall and large sap-filled vacuole identify a plant cell. Some plant cells do not photosynthesise and lack chloroplasts, so the absence of chloroplasts does not establish that it is an animal cell.
Why this answer works
- Use the positive evidence for a plant cell.
- Explain the limitation of the missing chloroplasts.
- Do not rely on shape alone.
Is this true? "Plants have chloroplasts instead of mitochondria."
Plant cells respire and contain mitochondria. Photosynthetic plant cells contain chloroplasts as well.