READ: Plants

4. Plant Cells

Plant Cells

Plant cells resemble other eukaryotic cells in many ways. For example, they are enclosed by a plasma membrane and have a nucleus and other membrane-bound organelles. A typical plant cell is represented by the diagram in Figure below.

Plant Cell Structures

Structures found in plant cells but not animal cells include a large central vacuole, cell wall, and plastids such as chloroplasts.

• The large central vacuole is surrounded by its own membrane and contains water and dissolved substances. Its primary role is to maintain pressure against the inside of the cell wall, giving the cell shape and helping to support the plant.
• The cell wall is located outside the cell membrane. It consists mainly of cellulose and may also contain lignin, which makes it more rigid. The cell wall shapes, supports, and protects the cell. It prevents the cell from absorbing too much water and bursting. It also keeps large, damaging molecules out of the cell.
• Plastids are membrane-bound organelles with their own DNA. Examples are chloroplasts and chromoplasts. Chloroplasts contain the green pigment chlorophyll and carry out photosynthesis. Chromoplasts make and store other pigments. They give flower petals their bright colors.

Types of Plant Cells

There are three basic types of cells in most plants. The three types are described in Table below. The different types of plant cells have different structures and functions.

CK-12 Foundation, Biology. http://creativecommons.org/licenses/by-nc-sa/3.0/

Types of Plant Cells

Type of Cell	Structure	Functions	Example
	Parenchymal	cube-shaped, loosely packed, thin-walled, relatively unspecialized, contain chloroplasts	photosynthesis, cellular respiration, storage	food storage tissues of potatoes
	Collenchymal	elongated, irregularly thickened walls	support, wind resistance	strings running through a stalk of celery
	Sclerenchymal	very thick cell walls containing lignin	support, strength	tough fibers in jute (used to make rope)