Search results
Results from the WOW.Com Content Network
Non-cellular life, also known as acellular life, is life that exists without a cellular structure for at least part of its life cycle. [1] Historically, most definitions of life postulated that an organism must be composed of one or more cells, [2] but, for some, this is no longer considered necessary, and modern criteria allow for forms of life based on other structural arrangements.
A plant cell wall was first observed and named (simply as a "wall") by Robert Hooke in 1665. [3] However, "the dead excrusion product of the living protoplast" was forgotten, for almost three centuries, being the subject of scientific interest mainly as a resource for industrial processing or in relation to animal or human health.
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.
The U.S. space agency's robotic OSIRIS-REx spacecraft in 2020 collected the samples from the near-Earth asteroid, a rocky remnant of a larger celestial body that had formed near the dawn of the ...
A syncytium (/ s ɪ n ˈ s ɪ ʃ i ə m /; pl.: syncytia; from Greek: σύν syn "together" and κύτος kytos "box, i.e. cell") or symplasm is a multinucleate cell that can result from multiple cell fusions of uninuclear cells (i.e., cells with a single nucleus), in contrast to a coenocyte, which can result from multiple nuclear divisions without accompanying cytokinesis. [1]
The components of the glycoprotein matrix help cell walls of adjacent plant cells to bind to each other. The selective permeability of the cell wall is chiefly governed by pectins in the glycoprotein matrix. Plasmodesmata (singular: plasmodesma) are pores that traverse the cell walls of adjacent plant cells. These channels are tightly regulated ...
Cell junctions [1] or junctional complexes are a class of cellular structures consisting of multiprotein complexes that provide contact or adhesion between neighboring cells or between a cell and the extracellular matrix in animals. [2] They also maintain the paracellular barrier of epithelia and control paracellular transport. Cell junctions ...
The entire surface of the plant has this outer layer of the epidermis. Hence it is also called surface tissue. Most of the epidermal cells are relatively flat. The outer and lateral walls of the cell are often thicker than the inner walls. The cells form a continuous sheet without intercellular spaces. It protects all parts of the plant.