**Plant Cell Structure and Function:**
– Plant cells have cell walls composed of cellulose, hemicelluloses, and pectin.
– Lignin or suberin may be secreted by the protoplast as secondary wall layers.
– Cell walls provide shape, facilitate communication, and plant-microbe interactions.
– Cell walls have small pores called plasmodesmata for exchange of nutrients and hormones.
**Types of Plant Cells and Tissues:**
– Major classes of cells and tissues include roots, stems, leaves, flowers, and reproductive structures.
– Parenchyma cells have functions ranging from storage and support to photosynthesis.
– Collenchyma cells provide support to growing plant parts.
**Parenchyma Cells:**
– Living cells with functions like storage, support, and photosynthesis.
– Some are specialized for light penetration and gas exchange regulation.
– Thin, permeable primary walls enable transport of small molecules.
**Collenchyma Cells:**
– Cells with thickened cellulose walls that provide support to growing plant parts.
– Lack lignin in the primary wall, offering flexible support.
– May be elongated and provide tensile strength to tissues.
**Sclerenchyma Cells and Tissues:**
– Composed of sclereids and fibers with thickened, lignified secondary walls.
– Sclereids provide protection to leaves and fruits, while fibers offer support.
– Typically dead at maturity and not involved in water and nutrient conduction.
Plant cells are the cells present in green plants, photosynthetic eukaryotes of the kingdom Plantae. Their distinctive features include primary cell walls containing cellulose, hemicelluloses and pectin, the presence of plastids with the capability to perform photosynthesis and store starch, a large vacuole that regulates turgor pressure, the absence of flagella or centrioles, except in the gametes, and a unique method of cell division involving the formation of a cell plate or phragmoplast that separates the new daughter cells.
