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Topic: Passive transport

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  rfc2126 - ISO Transport Service on top of TCP (ITOT)
The goal of this version is to minimise the number of changes to RFC1006 and ISO 8073 transport protocol definitions, while maximising performance, extending its applicability and protecting the installed base of RFC1006 users.
Transport Class 0 refines and supersedes the RFC1006 protocol and is aimed at preserving the RFC1006 installed base.
Transport Class 2 defines a number of new features which are not provided in RFC1006, such as independence of Normal and Expedited Data channels and Explicit Transport Disconnection.
www.rdesktop.org /docs/rfc2126.html   (4833 words)

  Passive Transport vs   (Site not responding. Last check: )
Passive transport involves carriers, channels, or direct diffusion through a membrane.
In active transport, a source of energy is required to move the carrier and its materials.
An example of primary active transport is the sodium pump.
biology.kenyon.edu /HHMI/Biol113/passive_vs_active.htm   (127 words)

Passive transport is transport which is driven by the gradient of chemical potential of the molecular species which is being transported.
Obviously, any transport that does not use only this source of energy to overcome the frictional resistances to movement must utilize some other source of energy, and if the transport occurs in opposition to a gradient of chemical potential, additional energy is required to increase the potential of the transported molecules.
This distinction between active and passive transport is not completely unambiguous, because it has neglected the possibility of interactions between a flux of one kind of molecule and the other molecules in the solution, which may induce fluxes of these molecules which would not be expected on the basis of their electrochemical potential distributions.
www.its.caltech.edu /~brokawc/Bi145/PassiveTransport.html   (2538 words)

 Passive Transport   (Site not responding. Last check: )
A molecule or ion that crosses the membrane by moving down a concentration or electrochemical gradient and without expenditure of metabolic energy is said to be transported passively.
All molecules and ions are in constant motion and it is the energy of motion - kinetic energy - that drives passive transport.
Transport of uncharged species across a membrane is dictated by differences in concentration of that species across the membrane - that is, by the prevailing concentration gradient.
arbl.cvmbs.colostate.edu /hbooks/cmb/cells/pmemb/passive.html   (124 words)

 biology - Passive transport
Passive transport is a means of moving biochemicals, and other atomic or molecular substances, across membranes.
The four main kind of passive transport are diffusion, facilitated diffusion, filtration and osmosis.
Since diffusion moves material from 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").
www.biologydaily.com /biology/Passive_transport   (518 words)

 Small Molecule Transport
Transport proteins can be inhibited by molecules that resemble the solute normally carried by the protein (similar to competitive inhibition in enzymes).
Transport protein might bind to solute in one conformation and deposit it on the other side of the membrane in another conformation.
Transport proteins involved in active transport harness energy from ATP to pump molecules against their concentration gradients.
home.earthlink.net /~dayvdanls/CampOLs/MemTransport.html   (1663 words)

 Cell Transport   (Site not responding. Last check: )
There are two types of cell transport, passive transport and active transport.
Passive transport is the movement of a substance through a cell membrane without the use of energy by the cell.
Active transport is the process by which a cell uses energy to move molecules from an area where they are less crowded to an area where the molecules are more crowded.
www.angelfire.com /me/howcellswork/transport.html   (146 words)

 Student Background Information
This membrane is a complex structure that is responsible for separating the contents of the cell from its surroundings, for controlling the movement of materials into and out of the cell, and for interacting with the environment surrounding the cell.
Active transport requires that the cell use energy that it has obtained from food to move the molecules (or larger particles) through the cell membrane.
Passive transport does not require such an energy expenditure, and occurs spontaneously.
biology.arizona.edu /sciconn/lessons/mccandless/reading.html   (1281 words)

 Passive Transport
Facilitated diffusion is a form of passive transport, when something hydrophilic needs to go down a concentration gradient in a phospholipid bilayer it uses a transport protein to help it, since inside the bilayer is hydrophobic.
passive transport is the transportation of electrolyte present in cell, from higher to lower concentration and it do no need any energy.....
When the molecule which is going to be transported joins to the permease, this protein suffers a conformational change and the molecule is pulled along into the cell.
www.biology-online.org /biology-forum/post-28419.html   (607 words)

 Membrane transport
Transport of nutrients, ions, and excretory substances from one side to the other is a major function of the cell membrane.
Passive diffusion of water regulated size of lymphocytes (white blood cells):  when a lymphocyte is placed in a hypertonic solution Þ the cell shrinks Þ internal pH decreases Þ export of H
Thus when considering transport of ions we must take into account their concentration gradient as well as the electrical gradient, the combined potential is called electrochemical potential.
fajerpc.magnet.fsu.edu /Education/2010/Lectures/12_Membrane_Transport.htm   (1302 words)

 SparkNotes: Cell Membranes: Structures Responsible for Membrane Transport
In addition to these two forms of transport, there exist other forms of transport such as endocytosis and exocytosis, which will be discuss later and do not require the same set of membrane proteins for their function.
Both of passive and active transport are mediated with the help of transmembrane proteins that act as transporters.
Transport proteins are critical to cell life and cell interactions.
www.sparknotes.com /biology/cellstructure/cellmembranes/section3.rhtml   (490 words)

 Passive transport - Wikipedia, the free encyclopedia
For example, metabolic activity will consume oxygen, which will reduce its concentration in the bloodstream; diffusion of oxygen in the alveoli of the lungs allows it to be replenished.
Facilitated diffusion is movement of molecules across the cell membrane via special transport proteins that are embedded within the cellular membrane.
Bear in mind, however, that facilitated diffusion is a passive process, and the solutes still move down the concentration gradient.
en.wikipedia.org /wiki/Passive_transport   (564 words)

 Passive transport
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.
Diffusion is the net movement of material from an area of high concentration of that material to an area with lower concentration.
Most cell membranes are permeable to water, and since the diffusion of water plays such an important role in the biological functioning of any living being, a special term has been coined for it -- osmosis.
www.mrsci.com /Physiology/Passive_transport.php   (496 words)

 Solute Transport   (Site not responding. Last check: )
Transport into or out of plant cells is across the plasma membrane lipid bilayer.  Bilayer is composed of phospholipids that have hydrophilic (affinity for water) and hydrophobic (low or no affinity for water) regions. 
Transport selectivity is due to proteins that are embedded across the membrane and have specific affinities for ions and other solutes, i.e.
Passive and active transport - passive is movement down a chemical potential gradient until equilibrium is reached, i.e., diffusion (Fick’s law, J
www.hort.purdue.edu /hort/courses/hort301/mikeslectures/WEB_SoluteTransport.html   (889 words)

 Diabetic Macular Edema: Passive and Active Transport of Fluorescein through the Blood-Retina Barrier -- Sander et al. ...
The preretinal fluorescein gradient is reversed compared to Figure 1 and the net, outward transport from the vitreous to the blood is indicated by the preretinal gradient.
The fluorescein concentration in the cell next to the retina is estimated from the plasma fluorescein concentration curve and passive and active transport estimates.
transport concomitant with the increase in passive permeability.
www.iovs.org /cgi/content/full/42/2/433   (3867 words)

 Passive transport, automobile transport, cell transport   (Site not responding. Last check: )
Whether passive transport occurs by osmosis, simple diffusion, or facilitated diffusion, it always involves a net movement of.
Many taxa may be capable of overriding passive "transport envelopes," either to retard or enhance dispersal (2) passive transport.
The passive transport of NOx emissions from aircraft studied with a passive transport.
www.lookbrand.com /transport/passive_transport.html   (264 words)

 celltools.html   (Site not responding. Last check: )
(Passive means not working; trans is a prefix that means across, and port means to carry) Quite literally, passive transport means to carry across without work.
Active transport is the movement of molecules across the cell membrane using energy.
In active transport, the molecules move mostly from areas of low concentration to areas of high concentration.
campus.udayton.edu /~cj/academics/GSPAGES/transport.html   (944 words)

 cell transport mechanisms   (Site not responding. Last check: )
Passive transport mechanisms do not require the cell to do work for the substance to enter or leave the cell.
Active transport mechanisms involve the cell to use cellular energy usually in the form of ATP to power special protein pumps to bring material into the cell.
The passive transport mechanisms and the protein pump mechanisms involve movement of substances as single molecules across the membrane.
staff.jccc.net /pdecell/cells/transport.html   (202 words)

 Botany online: Membranes and Transport   (Site not responding. Last check: )
It is also spoken of an active transport in contrast to passive transport that occurs only in the direction of the concentration gradient.
In order to understand passive transport is it necessary to understand a little of the topics diffusion, permeability and osmosis, too.
Active transport can be understood when knowing structure and function of integral proteins and the electrochemical properties of the membrane while the understanding of energy transformation requires information about all the molecules within the respective membrane.
www.biologie.uni-hamburg.de /b-online/e22/22.htm   (1136 words)

 Biol 1406- Biology I Interactive Tutorials
Diffusion, Dialysis and Osmosis Tutorial by RM Chute
Passive and Active Transport from Northland Community and Technical College
Les transport membranaires by Laurent Martorell Académie de Créteil
science.nhmccd.edu /biol/bio1int.htm   (598 words)

 Molecule Transport
For small molecules such as oxygen, ethanol, and carbon dioxide, the molecules could easily cross the membrane via passive transport, in the form of simple diffusion through a concentration gradient.
However, the means that cells use to transfer small molecules are not sufficient for transporting macromolecules, which include proteins, polynucleotides, and polysaccharides.
They are then transported to the Golgi complex by ER induced vesicles.
library.thinkquest.org /C004535/molecule_transport.html   (673 words)

 Cell Transportation Page
Materials move into and out of cells through either passive transport or active transport.
Molecules tend to move from crowded to less crowded in order to achieve a balance or to reach homeostasis.
passive transport - movement of molecules from a more crowded to a less crowded area WITHOUT the use of energy.
www.usoe.k12.ut.us /curr/science/sciber00/7th/cells/sciber/transpor.htm   (177 words)

 Passive Transport Disrupts Directional Path Integration by Rat Head Direction Cells -- Stackman et al. 90 (5): 2862 -- ...
Rats of the Passive Transport groups were placed into the wheeled-cart in the cylinder and then passively transported aboard the cart into the novel rectangle either in darkness or with the room lights illuminated.
C and D: tuning functions for rats that were passively transported into the novel rectangle either with the room lights on (C) or in darkness (D).
In contrast, HD cells of rats passively transported into the novel environment exhibited a preferred firing direction in the Return-Cylinder session that was approximately an average of that of the Initial Cylinder and Rectangle/Passageway preferred directions.
jn.physiology.org /cgi/content/full/90/5/2862   (9760 words)

 The Major Biological Transport Mechanisms Page
Most secondary active transport carrier proteins use energy provided by the transfer of Na down its concentration gradient to move another solute across the cell membrane.
These secondary active transport carriers can move solutes in the same direction as Na (co-transport into cells) or in the opposite direction of Na (counter transport out of cells).
We call these mechanisms "secondary active" transport mechanisms as the transport carriers involved do not use ATP BUT ATP is required to drive the Na ATP-dependent pump which maintains the Na gradient.
faculty.etsu.edu /currie/biotransport.htm   (758 words)

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