Parenchyma cells are alive when they perform their functions

The most numerous cell type in young plants is the parenchyma cell (Figure 35.9a). Parenchyma cells usually have thin walls, consisting only of a primary wall and the shared middle lamella. Many parenchyma cells have shapes with multiple faces. Most have large central vacuoles.

Secondary Wall Primary Wall

Secondary-walls

35.8 Pits Secondary walls may be interrupted by pits,which allow the passage of water and other materials between cells.

Secondary-walls

35.8 Pits Secondary walls may be interrupted by pits,which allow the passage of water and other materials between cells.

(a) Parenchyma cells

Cell walls

(.b) CoHenchyma cells

Cell walls

(a) Parenchyma cells

Cell walls

Sclerenchyma Cells

(.b) CoHenchyma cells

Cell walls

Leucoplasts Parenchyma Cell
50 |m

(c) Sclerenchyma: Fibers

Cell walls

(d) Sclerenchyma: Sclereids Secondary cell walls

(c) Sclerenchyma: Fibers

Cell walls

(d) Sclerenchyma: Sclereids Secondary cell walls

Sclereids Secondary Cell Walls

Vessel elements

Secondary cell wall

Vessel elements

Secondary cell wall

35.9 Plant Cell Types (a) Parenchyma cells in the leaf stem of Coleus. Note the thin, uniform cell walls. (b) Collenchyma cells make up the five outer cell layers of this spinach leaf vein. Their cell walls are thick at the corners of the cells and thin elsewhere. (c) Sclerenchyma: Fibers in a sunflower plant (Helianthus).The thick secondary walls are stained red. (d) Sclerenchyma: Sclereids. The extremely thick secondary walls of sclereids are laid down in layers.They provide support and a hard texture to structures such as nuts and seeds. (e) Water-conducting tracheids in pine wood.The thick cell walls are stained dark red. (f) Vessel elements in the stem of a squash. The secondary walls are stained red; note the different patterns of thickening, including rings and spirals.

The photosynthetic cells in leaves are parenchyma cells that contain numerous chloroplasts. Some nonphotosynthetic parenchyma cells store substances such as starch or lipids. In the cytoplasm of these cells, starch is often stored in specialized plastids called leucoplasts (see Figure 4.17b). Lipids may be stored as oil droplets, also in the cytoplasm. Some parenchyma cells appear to serve as "packing material" and play a vital role in supporting the stem. Many retain the capacity to divide and hence may give rise to new cells, as when a wound results in cell proliferation.

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Responses

  • jonna
    Are parenchyma cells alive?
    8 years ago
  • Sara
    How is parenchyma cells related to their function?
    8 years ago
  • Mehari
    Are parenchyma cell are uniform?
    8 years ago
  • Noora
    What are the functions of parenchyma cells in a stem?
    8 years ago
  • Ursula
    Are leukoplasts parenchyma cells?
    7 years ago
  • abel
    Are collenchyma cells alive?
    7 years ago

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