plant cells They are eukaryotic cells that differ in several key respects from the cells of other eukaryotic organisms. Its distinguishing characteristics include:

• Central vacuole is a large, water-filled volume surrounded by a membrane known as the vacuole tonoblast^[1][2] It maintains cell stability, controls the movement of molecules between the cytosol and sap, stores useful material and aids in the digestion of waste proteins and organelles.
• A cell wall composed of cellulose and hemicellulose, pectin and in many cases lignin, is secreted by protoplasts on the surface of the outer cell membrane. This contrasts with the cell walls of fungi (which are made of chitin), and bacteria, which are made of peptidoglycan.
• Pathways of specialized cell-to-cell communication are known as plasmodesmata.^[3] The pathway in the primary cell wall that is across the cell membrane and the endoplasmic reticulum^[4] for adjacent cells.
• Cytoplasmas, most notably chloroplasts, contain chlorophyll, a green colored pigment that is used to absorb sunlight and is used by the plant to produce its own food in a process known as photosynthesis. There are other types of cytospores, starch opiates, which are specialized in storing starch, zygotes, which are specialized in lipid storage, and chromoblasts, which are specialized in the synthesis and storage of pigments. As in mitochondria, which have 37 genes encoded by them,^[5] The cytospores have their own genome of about 100-120 unique genes^[6] Presumably, they arose as prokaryotic endosymbionts living in the cells of the primary eukaryotic ancestors of land plants and algae.^[7]
• Cell division by septoplasty as a template for building a cell plate later in cytokinesis is a feature of land plants and a few groups of algae, most notably the curia algae^[8] and the other order Trentepohliales^[9]
• The sperm of bryophytes and vascular symphytes possess flagella similar to those of animals.^[10][11] But higher species, (including gymnosperms and angiosperms) lack flagella and centrioles ^[12] that are found in animal cells.

Cell types[عدل]

• Plant parenchyma cells are living cells with diverse functions ranging from storage and support to photosynthesis and phloem loading (cell transport). Apart from the xylem and phloem in their vascular bundles, leaves are composed primarily of parenchyma cells. Some of the parenchyma cells, as in the epidermis, are specialized for light penetration and for concentrating or regulating the exchange of gases, but there are others among the less specialized cells of plant tissues, and many remain extensive, with the ability to divide to produce new aggregates of undifferentiated cells , throughout her life. Plant parenchyma cells have thin, permeable primary walls that enable the transport of small molecules between them, and the cytoplasm is responsible for a wide range of biochemical functions such as nectar secretion, or manufacture of by-products that discourage herbivory. The parenchyma cells of plants that contain many chloroplasts and are primarily concerned with photosynthesis are called chloroplasts. Others, such as the majority of plant parenchyma cells in potato tubers and seeds, cotyledons of legumes, have a storage function.
• Collenchyma Cells – Collenchyma cells survive to maturity and have only one primary wall. These cells mature from the meristematic derivatives that are the parenchyma of the plant initially, but the differences quickly become apparent. Plastids do not develop, and the secretory organs (ER and Golgi) are dotted into the secretory accessory primary wall. The wall is most common in thickness at the corners, where three or more cells join, and in thinness where only two cells join, although other arrangements of wall thickness can be found.^[13]

Pectin and hemicellulose are predominant constituents of the cell walls of the colloidal tissue of dicotyledonous dicotyledons, which may contain a small amount of about 20% cellulose per petazites.^[14] The cells of the colloid tissue are usually oblong, and may be segmented transversely to give a closed appearance. The role of this type of cell is to support the plant in the axons until it grows in length, and to impart flexibility and tensile strength to the tissues. The primary wall lacks the lignin that would make the wall rough and rigid, so this type of cell provides what might be called a plastic support – support that can hold a small stalk or petiole in the air, but in cells that can be supplied like the ones around it in height. An extended support (without an elastic snap back) is a good way to describe what the colloidal tissue does. Parts of the strings in celery are slimy tissues.

• periodontal cells – periodontal cells (from the Greek scleros، Solid) Rigid and rough cells with mechanical support function. These cells are of two broad types – sclereids or stony cells and fibrils. Cells develop an extensive secondary cell wall that is found down within the primary cell wall. The secondary wall is impregnated with lignin, which makes it rigid and impermeable. Therefore, these cells cannot survive for a long time because they cannot exchange enough materials to maintain an active metabolism. Periodontal cells are typically dead at the stage of functional maturity, and the cytoplasm is lost, leaving an empty central cavity.

The functions of scleridocytes (the tough cells that give leaves or fruits a sandy texture) include discouraging herbivory, by destroying digestive passages in the larval stages of small insects, and physical protection (the tough tissue of scleridocytes forms a pit wall in peaches and many other fruits) . The functions of the fibers include providing load-bearing support and tensile strength to the leaves and stems of herbaceous plants.^[13] Sclerenchyma fibers are not involved in the conduction of either water or nutrients (as in xylem) or of carbon compounds (as in phloem), but are likely to have evolved as modifications of xylem and vascular cell populations phloem in primary terrestrial plants.

Tissue types[عدل]

Major layers of cells differentiate from undifferentiated meristems (similar to animal stem cells) to form tissue structures of roots, stems, leaves, flowers, and reproductive structures.

The formation of xylem cells ^[15] Cells are elongated, with a serrated secondary thickening of the cell walls. Xylem cells are specialized for conducting water, and first appeared in plants during their transition to land in the Silurian period more than 425 million years ago (see coxonia (Cooksonia)). Possession of xylem vascular tissue defines vascular plants or trachophytes. Shown as tracheids of the xylem, elongated xylem cells, the simpler ones having continuous primary cell walls and a serrated secondary wall thickness in the form of overlapping rings, collars or networks. More complex tracheids with tracheal-like holes are called finite pits and are characteristic of gymnosperms. Ferns, other vascular nonflowering plants, and gymnosperms have only xylem tracheids, while angiosperms also have xylem vessels. The vessels’ organs are hollow xylem cells arrayed end-to-end, without end walls which are grouped into long continuous tubes. Mosses lack true xylem cells, but their sporophyte has a water-conducting tissue known as a hydrome consisting of elongated cells of simpler configuration.

Phloem is a specialized food-conducting tissue in higher plants. Food delivery is a complex process that takes place in a plant with the help of a cell called phloem cells. These cells deliver intracellular and intracellular fluids (food proteins and other essential elements required by the plant for its own metabolism) via the process of osmosis. This phenomenon is called sap rise in plants. The phloem consists of two types of cells, sieve tube cells and closely related load cells. Sieve tube elements lack a nucleus and a ribosome, and metabolism and functions are regulated by neighboring nucleated load cells. The sieve tubes are welded end-to-end with perforated end plates known as Sieve plate plates, which allows the transfer of photosynthesis between the sieve elements. The load cells, which are connected to the sieve tubes by plasmodesmata, are responsible for loading the phloem with sugars. Mosses lack phloem, but sporophyte mosses have a simpler tissue with a similar function called the leptome.

They are the outer layered cells of the plant, specialized in the parenchyma cells that cover the outer surfaces of leaves, stems, and roots. The outer layer cells of the air organs arise from the superficial layer of cells known as the tunic (first and second layers) covering the growing apex,^[13] Whereas the cortex and vascular tissue arise from a deeper layer of the developing apex known as the apical epithelium Corps (corpus) (third class). The outer layer of roots stems from the cellular layer just below the root cap.

The outer layers of all aerial organs – but not of the roots – are covered by a cortex consisting of polyester cutin with a waxy surface layer. It is believed that the cells of the outer layer of the primary embryo are only plant cells with a biochemical capacity to synthesize cutin.^[16] Several cell types are likely to be present in the outer layer. The stomatal guard cells are among the most prominent of these cells, along with the glandular cells and the vestigial hairs or threchium, and the root hairs of the primary roots. In the outer posterior layer of most plants, only the guard cells have chloroplasts.

organelles[عدل]

• cell membrane
• cell wall
• nuclear membrane
• plasmodesmata
• succulent gap
• cellular manufacturers
• Chloroplasts
• White Jubailah
• color builders
• Golgian devices
• ribosome
• Network ER
• mitochondria;
• allolysis
• protoplast
• Nucleus
• deoxyribonucleic acid
• chromosomes
• ribonucleic acid
• cytoskeleton
• nucleolus

the reviewer[عدل]

Read also[عدل]

• living cell
• Animal cell

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