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The cell nucleus (from Latin nucleus or nuculeus 'kernel, seed'; pl.: nuclei) is a membrane-bound organelle found in eukaryotic cells.Eukaryotic cells usually have a single nucleus, but a few cell types, such as mammalian red blood cells, have no nuclei, and a few others including osteoclasts have many.
A well-studied stimulus is strong blue light, which drives movement of nuclei to anticlinal (perpendicular to the plane of the leaf) cell walls in mesophyll and epidermal cells of Arabidopsis thaliana plants. [4] Chloroplasts moving in response to blue light associate with the nucleus to move the nucleus to the appropriate location. [5]
Structure of a plant cell. 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 ...
Flagella may have hairs (mastigonemes), as in many stramenopiles. Their interior is continuous with the cell's cytoplasm. [42] [43] Centrioles are often present, even in cells and groups that do not have flagella, but conifers and flowering plants have neither. They generally occur in groups that give rise to various microtubular roots.
Another structure identified within many nucleoli (particularly in plants) is a clear area in the center of the structure referred to as a nucleolar vacuole. [15] Nucleoli of various plant species have been shown to have very high concentrations of iron [16] in contrast to human and animal cell nucleoli.
Organelles (literally "little organs") are usually membrane-bound structures inside the cell that have specific functions. Some major organelles that are suspended in the cytosol are the mitochondria, the endoplasmic reticulum, the Golgi apparatus, vacuoles, lysosomes, and in plant cells, chloroplasts.
a Cells of the same lineage fuse to form a cell with multiple nuclei, known as a syncytium. The fused cell can have an altered phenotype and new functions such as barrier formation. b Cells of different lineage fuse to form a cell with multiple nuclei, known as a heterokaryon. The fused cells might have undergone a reversion of phenotype or ...
Some eukaryotic cells (plant cells and fungal cells) also have a cell wall. Inside the cell is the cytoplasmic region that contains the genome (DNA), ribosomes and various sorts of inclusions. [2] The genetic material is freely found in the cytoplasm. Prokaryotes can carry extrachromosomal DNA elements called plasmids, which are usually circular.