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Encyclopedia > Passive transport

Passive transport means moving biochemicals and other atomic or molecular substances across membranes. Unlike active transport, this process does not involve chemical energy. Passive transport is dependent on the permeability of the cell membrane, which, in turn, is dependent on the organization and characteristics of the membrane lipids and proteins. The four main kinds of passive transport are diffusion, facilitated diffusion, filtration and osmosis. This article or section is in need of attention from an expert on the subject. ... Biochemistry (from Greek: , bios, life and Egyptian kēme, earth[1]) is the study of the chemical processes in living organisms. ... Properties For other meanings of Atom, see Atom (disambiguation). ... 3D (left and center) and 2D (right) representations of the terpenoid molecule atisane. ... Look up cell membrane in Wiktionary, the free dictionary. ... Sodium-Potassium pump, an example of Primary active transport secondary active transport Active transport (sometimes called active uptake) is the mediated transport of biochemicals, and other atomic/molecular substances, across membranes. ... For other uses, see Chemistry (disambiguation). ... diffusion (disambiguation). ... facilitated diffusion in cell membrane, showing ion channels and carrier proteins Facilitated diffusion (or facilitated transport) is a process of diffusion, a form of passive transport, where molecules diffuse across membranes, with the assistance of transport proteins. ... Look up filtration in Wiktionary, the free dictionary. ... Osmosis is the spontaneous net movement of water across a semipermeable membrane from a region of low solute concentration to a solution with a high solute concentration, down a solute concentration gradient. ...

Contents

Diffusion (Simple)

Passive diffusion on a cell membrane.
Main article: Diffusion

Diffusion is the net movement of unicorns from an area of high concentration of zebras of that material to an area with lower concentration of dragons. The difference of concentration between the two areas is often termed as the concentration gradient, and diffusion will continue until this gradient has been eliminated. Since diffusion moves materials from an area of higher concentration to the lower, it is described as moving solutes "down the concentration gradient" (compared with active transport, which often moves material from area of low concentration to area of higher concentration, and therefore referred to as moving the material "against the concentration gradient"). Image File history File links Simple_difussion_in_cell_membrane. ... Image File history File links Simple_difussion_in_cell_membrane. ... diffusion (disambiguation). ... Sodium-Potassium pump, an example of Primary active transport secondary active transport Active transport (sometimes called active uptake) is the mediated transport of biochemicals, and other atomic/molecular substances, across membranes. ...


Facilitated diffusion

Facilitated diffusion on a cell membrane.
Main article: Facilitated diffusion

Facilitated diffusion, also called carrier-mediated diffusion, is the movement of molecules across the cell membrane via special transport proteins that are embedded within the cellular membrane. Many large molecules, such as glucose, are insoluble in lipids and too large to fit through the membrane pores. Therefore, it will bind with its specific carrier proteins, and the complex will then be bonded to a receptor site and moved through the cellular membrane. Bear in mind, however, that facilitated diffusion is a passive process, and the solutes still move down the concentration gradient. The alveoli are tiny grapelike sacs located at the end of the bronchial tubes. This is where oxygen diffuses into the alveoli and is exchanged for carbon dioxide. Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... facilitated diffusion in cell membrane, showing ion channels and carrier proteins Facilitated diffusion (or facilitated transport) is a process of diffusion, a form of passive transport, where molecules diffuse across membranes, with the assistance of transport proteins. ... 3D (left and center) and 2D (right) representations of the terpenoid molecule atisane. ... Look up cell membrane in Wiktionary, the free dictionary. ... A transport protein is a protein involved in facilitated diffusion. ... Glucose (Glc), a monosaccharide (or simple sugar), is an important carbohydrate in biology. ... Some common lipids. ... In biochemistry, a receptor is a protein on the cell membrane or within the cytoplasm or cell nucleus that binds to a specific molecule (a ligand), such as a neurotransmitter, hormone, or other substance, and initiates the cellular response to the ligand. ... A concentration gradient is the difference in density of a substance over a distance. ... The alveoli (singular:alveolus), tiny hollow sacs which are continuous with the airways, are the sites of gas exchange with the blood. ... The bronchioles are the first airway branches that no longer contain cartilage. ...


Filtration

Main article: Filtration

Filtration is movement of water and solute molecules across the cell membrane due to hydrostatic pressure generated by the cardiovascular system. Depending on the size of the membrane pores, only solutes of a certain size may pass through it. For example, the membrane pores of the Bowman's capsule in the kidneys are very small, and only albumins, the smallest of the proteins, have any chance of being filtered through. On the other hand, the membrane pores of liver cells are extremely large, to allow a variety of solutes to pass through and be metabolized. Image File history File links Filtration_diagram. ... Image File history File links Filtration_diagram. ... Look up filtration in Wiktionary, the free dictionary. ... This article is about pressure in the physical sciences. ... The Bowmans capsule(other names: capsula glomeruli, glomerular capsule) is a cup like sac at the beginning of the tubular component of a nephron in the mammalian kidney. ... You may be looking for albumen, or egg white. ... For the bird, see Liver bird. ...


Osmosis

Effect of osmosis on blood cells under different solutions.
Effect of osmosis on blood cells under different solutions.
Main article: Osmosis

Osmosis is the diffusion of water molecules across a partially permeable membrane. The net movement of water molecules through a partially permeable membrane from a solution of high water potential to an area of low water potential. A cell with a less negative water potential will draw in water but this depends on other factors as well such as solute potential (pressure in the cell e.g. solute molecules) and pressure potential (external pressure e.g. cell wall). Image File history File links Osmotic_pressure_on_blood_cells_diagram. ... Image File history File links Osmotic_pressure_on_blood_cells_diagram. ... Osmosis is the spontaneous net movement of water across a semipermeable membrane from a region of low solute concentration to a solution with a high solute concentration, down a solute concentration gradient. ... diffusion (disambiguation). ... In science, a molecule is the smallest particle of a pure chemical substance that still retains its chemical composition and properties. ...


See also

Sodium-Potassium pump, an example of Primary active transport secondary active transport Active transport (sometimes called active uptake) is the mediated transport of biochemicals, and other atomic/molecular substances, across membranes. ... The first edition of Transport Phenomena was published in 1960, two years after having been preliminarily published under the title Notes on Transport Phenomena based on mimeographed notes prepared for a chemical engineering course taught at the University of Wisconsin during the academic year 1957-1958. ... A biological membrane or biomembrane is an enclosing or separating tissue which acts as a barrier within or around a cell. ... diffusion (disambiguation). ... facilitated diffusion in cell membrane, showing ion channels and carrier proteins Facilitated diffusion (or facilitated transport) is a process of diffusion, a form of passive transport, where molecules diffuse across membranes, with the assistance of transport proteins. ... Osmosis is the spontaneous net movement of water across a semipermeable membrane from a region of low solute concentration to a solution with a high solute concentration, down a solute concentration gradient. ... Sodium-Potassium pump, an example of Primary active transport secondary active transport Active transport (sometimes called active uptake) is the mediated transport of biochemicals, and other atomic/molecular substances, across membranes. ... example of Primary active transport Primary active transport directly uses energy to transport molecules across a membrane. ... secondary active transport In secondary active transport, in contrast to primary active transport, there is no direct coupling of ATP; instead, the electrochemical potential difference created by pumping ions out of the cell is used. ... Neuron A (transmitting) to neuron B (receiving) 1. ... Endocytosis (IPA: ) is a process whereby cells absorb material (molecules such as proteins) from the outside by engulfing it with their cell membrane. ... Steps of a macrophage ingesting a pathogen: a. ... Transcytosis is the process by which various macromolecules are transported across the interior of a cell. ... Pinocytosis or cell drinking is one of three forms of endocytosis, a cellular process that is used to take up smaller particles in cell by splitting in small particles , and forms vesicles which then merge with lysosomes to hydrolyze (hydrolytic enyzmes) to break down the particles. ... Pinocytosis Non-specific, adsorptive pinocytosis is a form of endocytosis, a process in which small particles are taken in by a cell by splitting off small vesicles from the cell surface. ...

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rfc2126 - ISO Transport Service on top of TCP (ITOT) (4833 words)
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