Comparing Features of Eukaryotic Cells: Animal, Plant, and Fungal Cells
- Plants, fungi, and animals are organisms that seem distinct, yet their cells share a common blueprint: the eukaryotic cell.
- However, the structural differences between animal, plant, and fungal cells reflect their unique roles in nature.
Cell Walls: Strength and Protection
Plant Cells
- The cell wall, made of cellulose, is like a suit of armor.
- It maintains shape, withstands stress, and prevents water-induced bursting.
Despite its rigidity, it is freely permeable to water, gases, and nutrients.
Fungal Cells
- Fungal cell walls are made of chitin, a flexible and strong polymer.
- This composition allows fungi to thrive in diverse environments, from decaying logs to food storage.
- Many students incorrectly assume that fungal cell walls are made of cellulose.
- In fact, they are composed of chitin, a key difference tested in IB examinations.
Animal Cells
- Animal cells lack a cell wall.
- Instead, they depend on a plasma membrane for flexibility, enabling diverse shapes and movements.
Animal cells do not have cell walls, which is why they are more flexible and dynamic compared to the rigid structures of plants and fungi.
Vacuoles: Storage and Pressure Regulation
Plant Cells
- A large central vacuole, often occupying up to 90% of the cell, stores water, nutrients, and waste.
- It also maintains turgor pressure, keeping plants upright and leaves firm.
- When drawing plant cells in IB Biology exams, always include a large central vacuole.
- Omitting it is a common way to lose marks, as this is a key structural feature distinguishing plant cells from animals and fungi.
Fungal Cells
- Vacuoles are also present and often large, but their composition and function vary.
- They are primarily involved in storage, osmoregulation, and recycling of cellular components.
Animal Cells
- Vacuoles are small and temporary.
- They are often involved in isolating waste or engulfing food during processes like endocytosis.
- In plants, the central vacuole can store pigments that give flowers their bright colors or toxins that deter herbivores.
- In fungi, vacuoles might store enzymes for digesting nutrients.
- In animals, a vacuole could temporarily store food particles during digestion.
