Botany · Ch 6 — Cell: The Unit of Life
Ultra Structure of Eukaryotic Cell
Ultra Structure of Eukaryotic Cell
Comparing an animal cell and a plant cell side by side is a useful way to see both what eukaryotic cells share and where they genuinely diverge. Both are bounded by a plasma (cell surface) membrane, and both hold a protoplasm containing a nucleus alongside the standard set of organelles: endoplasmic reticulum, mitochondria, Golgi bodies, ribosomes and a supporting cytoskeleton. Animal cells generally stop there, plus centrioles and comparatively more numerous lysosomes. A typical plant cell, however, adds three further features that an animal cell lacks under normal circumstances: a prominent, rigid cell wall surrounding the plasma membrane; plastids, most importantly the photosynthetic chloroplast; and one large, permanent central vacuole (bounded by its own membrane, the tonoplast) that can occupy most of the cell's interior volume and is central to maintaining the cell's water balance and turgor. These structural differences are not cosmetic - the cell wall is what gives plant cells their fixed shape and resistance to bursting, and it is precisely the prese …
What this figure shows. Two labelled cutaway cells side by side: the Animal cell shows plasma membrane, nucleus with nucleolus, mitochondria, rough and smooth endoplasmic reticulum, Golgi apparatus, lysosomes, centrioles, ribosomes and cytoskeleton; the Plant cell shows the same organelle set plus a thick cell wall outside the plasma membrane, chloroplasts, and one large central vacuole bounded by a tonopla …
What this figure shows. A detailed labelled plant cell diagram showing, from outside in: cell wall (with plasmodesmata connecting to a neighbouring cell), plasma membrane, cytoplasm, nucleus (with nuclear envelope, nuclear pores and nucleolus), a large central vacuole with tonoplast, rough and smooth endoplasmic reticulum, Golgi apparatus/dictyosomes, mitochondria, chloroplasts (with grana), ribo …
What this figure shows. A composite labelled diagram summarising a generalised eukaryotic cell's components in one view: plasma membrane, cell wall (plant), cytoplasm/cytosol, nucleus with chromatin and nucleolus, endoplasmic reticulum, Golgi apparatus, mitochondria, chloroplast, ribosomes (free and ER-bound), lysosomes, vacuole and cytoskeletal filaments, positioned relative to one anot …
| S.No | Plant cell | Animal Cell |
|---|---|---|
| 1 | Usually larger than animal cells | Usually smaller than plant cells |
| 2 | Cell wall present (middle lamellae, primary and secondary walls) | Cell wall absent |
| 3 | Plasmodesmata present | Plasmodesmata absent |
| 4 | Chloroplast present | Chloroplast absent |
| 5 | Vacuole large and permanent | Vacuole small and temporary |
| 6 | Tonoplast present around vacuole | Tonoplast absent |
| 7 | Centrioles absent except motile cells of lower plants | Centrioles present |
| 8 | Nucleus present along the periphery of the cell | Nucleus at the centre of the cell |