Plant cell parts and functions pdf

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Plant Cell Parts and Functions (Interactive Tutorial)

Plant cells are eukaryotic 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.

Plant cells differentiate from undifferentiated meristematic cells analogous to the stem cells of animals to form the major classes of cells and tissues of roots , stems , leaves , flowers , and reproductive structures, each of which may be composed of several cell types. Parenchyma cells are living cells that have functions ranging from storage and support to photosynthesis mesophyll cells and phloem loading transfer cells.

Apart from the xylem and phloem in their vascular bundles, leaves are composed mainly of parenchyma cells. Some parenchyma cells, as in the epidermis, are specialized for light penetration and focusing or regulation of gas exchange , but others are among the least specialized cells in plant tissue, and may remain totipotent , capable of dividing to produce new populations of undifferentiated cells, throughout their lives. Parenchyma cells that contain many chloroplasts and are concerned primarily with photosynthesis are called chlorenchyma cells.

Others, such as the majority of the parenchyma cells in potato tubers and the seed cotyledons of legumes , have a storage function. Collenchyma cells are alive at maturity and have thickened cellulose cell walls. Plastids do not develop, and the secretory apparatus ER and Golgi proliferates to secrete additional primary wall.

The wall is most commonly thickest at the corners, where three or more cells come in contact, and thinnest where only two cells come in contact, though other arrangements of the wall thickening are possible.

The role of this cell type is to support the plant in axes still growing in length, and to confer flexibility and tensile strength on tissues. The primary wall lacks lignin that would make it tough and rigid, so this cell type provides what could be called plastic support — support that can hold a young stem or petiole into the air, but in cells that can be stretched as the cells around them elongate. Stretchable support without elastic snap-back is a good way to describe what collenchyma does.

Parts of the strings in celery are collenchyma. Sclerenchyma is a tissue composed of two types of cells, sclereids and fibres that have thickened, lignified secondary walls [17] : 78 laid down inside of the primary cell wall. The secondary walls harden the cells and make them impermeable to water.

Consequently, sclereids and fibres are typically dead at functional maturity, and the cytoplasm is missing, leaving an empty central cavity. Sclereids or stone cells, from the Greek skleros, hard are hard, tough cells that give leaves or fruits a gritty texture. They may discourage herbivory by damaging digestive passages in small insect larval stages.

Sclereids form the hard pit wall of peaches and many other fruits, providing physical protection to the developing kernel. Fibres are elongated cells with lignified secondary walls that provide load-bearing support and tensile strength to the leaves and stems of herbaceous plants. Sclerenchyma fibres are not involved in conduction, either of water and nutrients as in the xylem or of carbon compounds as in the phloem , but it is likely that they evolved as modifications of xylem and phloem initials in early land plants.

Xylem is a complex vascular tissue composed of water-conducting tracheids or vessel elements , together with fibres and parenchyma cells. Tracheids [19] are elongated cells with lignified secondary thickening of the cell walls, specialised for conduction of water, and first appeared in plants during their transition to land in the Silurian period more than million years ago see Cooksonia.

The possession of xylem tracheids defines the vascular plants or Tracheophytes. Tracheids are pointed, elongated xylem cells, the simplest of which have continuous primary cell walls and lignified secondary wall thickenings in the form of rings, hoops, or reticulate networks. More complex tracheids with valve-like perforations called bordered pits characterise the gymnosperms. The ferns and other pteridophytes and the gymnosperms have only xylem tracheids , while the flowering plants also have xylem vessels.

Vessel elements are hollow xylem cells without end walls that are aligned end-to-end so as to form long continuous tubes. The bryophytes lack true xylem tissue, but their sporophytes have a water-conducting tissue known as the hydrome that is composed of elongated cells of simpler construction.

Phloem is a specialised tissue for food transport in higher plants, mainly transporting sucrose along pressure gradients generated by osmosis, a process called translocation. Phloem is a complex tissue, consisting of two main cell types, the sieve tubes and the intimately associated companion cells , together with parenchyma cells, phloem fibres and sclereids.

The sieve tube elements lack nuclei and ribosomes , and their metabolism and functions are regulated by the adjacent nucleate companion cells. The companion cells, connected to the sieve tubes via plasmodesmata , are responsible for loading the phloem with sugars. The bryophytes lack phloem, but moss sporophytes have a simpler tissue with analogous function known as the leptome. The plant epidermis is specialised tissue, composed of parenchyma cells, that covers the external surfaces of leaves, stems and roots.

Several cell types may be present in the epidermis. Notable among these are the stomatal guard cells that control the rate of gas exchange between the plant and the atmosphere, glandular and clothing hairs or trichomes , and the root hairs of primary roots.

In the shoot epidermis of most plants, only the guard cells have chloroplasts. Chloroplasts contain the green pigment chlorophyll which is needed for photosynthesis. The epidermal cells of aerial organs arise from the superficial layer of cells known as the tunica L1 and L2 layers that covers the plant shoot apex , [17] whereas the cortex and vascular tissues arise from innermost layer of the shoot apex known as the corpus L3 layer.

The epidermis of roots originates from the layer of cells immediately beneath the root cap. The epidermis of all aerial organs, but not roots, is covered with a cuticle made of polyester cutin or polymer cutan or both , with a superficial layer of epicuticular waxes.

The epidermal cells of the primary shoot are thought to be the only plant cells with the biochemical capacity to synthesize cutin. From Wikipedia, the free encyclopedia. The type of eukaryotic cell present in green plants. For the scientific journal, see The Plant Cell. Cross section of a leaf showing various plant cell types. Plant Physiology. Advances in Botanical Research.

New Phytologist. Seminars in Cell Biology. Encyclopedia Britannica. Retrieved Bibcode : Natur. Nucleic Acids Research. Origin of eukaryotic cells. New Haven: Yale University Press. American Journal of Botany. International Journal of Systematic and Evolutionary Microbiology. Lessons from Chlamydomonas reinhardtii ". Journal of Experimental Botany. Transactions of the American Microscopical Society. New York: W.

Akademie der Wissenschaften in Wien Sitzungsberichte. Plant Anatomy Part 1. Cells and Tissues. London: Edward Arnold. The plant cell wall. In: Plant Cuticles. History of botany. Plant morphology glossary. Cell wall Phragmoplast Plastid Plasmodesma Vacuole.

Plant physiology Materials. Evolution Ecology. Agronomy Floriculture Forestry Horticulture. Botanical terms Botanists by author abbreviation Botanical expedition. Category WikiProject. Categories : Plant cells Plant anatomy Eukaryotic cells. Hidden categories: Articles with short description Short description is different from Wikidata Wikipedia pages semi-protected against vandalism. Namespaces Article Talk. Views Read View source View history. Help Learn to edit Community portal Recent changes Upload file.

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Plant Cell

Animal cells usually have an irregular shape, and plant cells usually have a regular shape. Cells are made up of different parts. It is easier to describe these parts by using diagrams:. Animal cells and plant cells both contain:. Plant cells also contain these parts, which are not found in animal cells:. The table summarises the functions of these parts:.

Plant cells are eukaryotic 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. Plant cells differentiate from undifferentiated meristematic cells analogous to the stem cells of animals to form the major classes of cells and tissues of roots , stems , leaves , flowers , and reproductive structures, each of which may be composed of several cell types. Parenchyma cells are living cells that have functions ranging from storage and support to photosynthesis mesophyll cells and phloem loading transfer cells. Apart from the xylem and phloem in their vascular bundles, leaves are composed mainly of parenchyma cells. Some parenchyma cells, as in the epidermis, are specialized for light penetration and focusing or regulation of gas exchange , but others are among the least specialized cells in plant tissue, and may remain totipotent , capable of dividing to produce new populations of undifferentiated cells, throughout their lives.

Plant cell

Many plant cell organelles are also found in animal cells. For an overview of animal cells, see the previous tutorial. Part 1 is the cell wall.

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Cell Organelles Quiz Answers. Take a look at the question and choose the correct answer by clicking on one of the images down below!. Answer to A eukaryotic cell contains many compartmentalized organelles that organize its interior.

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