what is facilitated diffusion?
829520
Solutes that are too polar or highly charged to diffuse through the lipid bilayer and are too big to diffuse through membrane channels can cross the plasma membrane by facilated difussion.In this process, a solute binds to a specific transporter on one side of the membrane and is released on the other side after the transporter undergoes a changhe in shape.\n\nLike diffusion, facilitated diffusion is a passive process.The net result of facilitated diffusion is movement down a concentration gradient.The solute binds more often to the transporter on the side of the membrane with a higher concentration of solute.Once the concentration is the same on the both sides of the membrane,solute molecules bind to the transporter on the cystolic side and move out the extracellular side and move into the cytosol.The rate of facilitated diffusion(how quickly it occurs) is determined by the stepness of the concentration gradient across the membrane.\n\nThe number of transporters available in a plasma membrane places an upper limit,called the transport maximum,on the rate at which facilitated diffusion can occur.Once all the transporters are occupied, the transport maximum is reached, and further increase in the concentration gradient does not increase the rate of facilitated diffusion.Thus,much like a completely saturated sponge can absorb no more water,the process of facilitated diffusion exhibits saturation.\n\nHope this helps you.Please check my spelling too.I may misspelled some words.So many too typed.No time to check it.\n(^^o)/
1025467
A plasmolyzed cell is a "pickeled" plant cell, meaning that it was placed in a hypertonic solution (high salt or sugar solution compared to the cell itself). If the plant has chloroplasts, one can see all the chloroplasts "balling up" and getting crowded in the small cytosol-cytoplasm space during plasmolysis. If the plant cell is put in a 10% solution (and the cell is 0.9% salt itself in the cytoplasm) then there is a net movement of water from high water in the cytoplasm-cytosol of the cell to the area of lower water concentration in the space between the cell mbn and the cell wall until equilibrium is reached.  This is a form of diffusion called osmosis.  \n\nComparable event happens when an animal cell, like an rbc is put in a hypertonic solution.  RBC becomes dehydrated and shrivelled, a process called CRENATION.\n\nBTW, the solutes also move-diffuse from high conc to low as well (aka dialysis, the diffusion of solutes), meaning they move from high solute-low water, to lower solute, higher water until equilibrium is reached.  But the water effects are greater if the solute concentration is not too high, too hypertonic.
1175500
catalyst :- substance which increase the rate of reactoin without being get consumed in it.\nenzyme :- boilogical catalyst which increase the rate of boilogical reaction \n                  e.g.    amaylase enzyme found in human saliva\nsacrificial protection :- reduction of corrosion of a metal in an electrolyte by galvanically coupling it to a more anodic metal\n\n\n\nvisit for more infor mation on corrsion\n\n\nwww.corrosionsource.com/handbook/glossary
733835
Some diffuse across the membrane.  The membrane is semipermeable  meaning that it allows some things to diffuse accross and some cannot pass at all.  example: Water will diffuse accross.\n\nTheir a various channels in the membrane that will transport items into and out of a cell even against a concentration gradient.\nTheir are calcium and sodium channels.\n\nSome are engulfed by animal cells: example:  white blood cells will engulf bacteria:phagocytossis
596473
Diffusion is the spontaneous spreading of something such as particles, heat, or momentum. The phenomenon is readily observed when a drop of colored water is added to clear water, or when smoke from a chimney dissipates into the air. In these cases, diffusion is the result of turbulent fluid motion rather than chemical reactions or the application of external force. In cell biology, diffusion is described as a form of "passive transport", by which substances cross membranes. \n\nOsmosis is the diffusion of a solvent through a semipermeable membrane from a region of low solute concentration to a region of high solute concentration. The semipermeable membrane is permeable to the solvent, but not to the solute, resulting in a chemical potential difference across the membrane which drives the diffusion.
566605
A diffusion as defined by Webster is "the act of diffusing (separating) or the state of being diffused (separated)," etc, etc. However, I am a study of herbs and herbalism and I cannot find a mention of "diffusion" in my books. However, an "infusion: the soaking of leaves, flowers, soft stems and some roots by pouring boiling water over them" and a "decoction: boiling tough or hard plant parts in liquid." Let me know if you need something else. :)
867974
Oxygen transfers via osmosis through cell walls  from regions of high concentration (ie, the haemoglobin) to the tissue cells where there is a lower concentration. At the same time the tissue cells release carbon dioxide which lowers the partial pressure creating a diffusion gradient for the the oxygen to move along.
118426
thermal diffusivity (symbol: α) is the ratio of thermal conductivity to volumetric heat capacity.\nThermo diffusivity is a measure of the rate at which a temperature disturbance at one point in a body travels to another point. It is expressed by the relationship K/dCp, where K is the coefficient of thermal conductivity, d is the density, and Cp is the specific heat at constant pressure
894576
Diffusion is simply the natural movement of ions and small molecules, usually from one side of a membrane to another, but also throughout a liquid. They always flow from more concentrated to less concentrated. So the concentration gradient between the cell and its environment determines which direction the molecules/ions move.
246103
The proton pump represents the flow of protons from the mitochondrial matrix into the intermembrane space.  This flow of protons (driven by the electron transport chain) creates an electrochemical gradient with increased numbers of protons in the intermembrane space.  This gradient of protons provides the force to drive Complex V which produces ATP from ADP.
702599
First of all, osmosis is the movement of WATER ONLY!  Diffusion is the movement of any other substance.  If there are two solutions separated by a semi-permeable membrane, then water from the side of lower solute concentration will move to the side of higher solute concentration.  The walls of a capillary are a semi-permeable membranes, so the same thing will happen in a capillary
1042750
Since the oxygen is leaving an area of higher concentration into an area of low concentration (lungs to blood) and the carbon dioxide is doing the reverse the process is called diffusion.
192408
Ionophores- They havea negatively charged channel that allows the solute to enter\n\nFacilitated diffusion- Essentially they capture a solute and tug it into the cell.\n\nactive transport- i believe they look similarly to proteins that facilitate diffusion
562274
Diffusion of a Dye in Hot and Cold Water\n\nPurpose:  The purpose of this experiment is to demonstrate the principle of diffusion.  Diffusion is the net movement of particles (atoms, ions, or molecules) from an area of greater concentration to areas of lesser concentration.\n\nMaterials and Methods:  For this experiment, the student will require a projector, two petri dishes, two 150 ml beakers, hot plate, potassium permanganate (purple dye), and a spatula.  Obtain about 50 ml of cold water in one beaker and about 50 ml or boiling water in the other.  Place the petri dishes on the projector and add cold water to one dish and boiling water to the other.  Allow the water in the dishes to become still.  Using the spatula, add a crystal of potassium permanganate to the center of each dish\n\nExperiment:  Observe the experiment for several minutes and note what happens to the purple dye in each petri dish.\n\nConclusion:  Do you observe diffusion in each?\n\nHow does the rate of diffusion differ? \n\nWhy is there a greater rate of diffusion in one
965419
Yes; think of the cell as a sack filled with stuff surrounded by a semipermeable membrane. Water diffuses through the pores based on its concentration. That is, water goes from an area of great to less concentration. Since the distilled water by definition has no solute and is 100 per cent pure and since the concentration of the water in the cell is diluted by the presence of small particles (almost one percent), water flows from the outside to the inside very quickly. The membrane is stretched so much by the infusion of water that it bursts.
133310
The simple explanation to explain the two is this: in diffusion, chemicals move down a chemical gradient (ie from a place of high concentration to a place of low concentration, the same way that heat flows from a hot object to a cold object).\n\nSimple diffusion is when a chemical transverses any membranes of it's own accord.  For instance, the brain is sheilded from the potentially toxic material in the blood stream by a layer of lipid-rich cells that line the cerebral blood vessels.  The only things that can get through this barrier are those that have special gates in the cell membranes to allow them through (either by facilitated diffusion or active transport), or if a chemical is sufficiently lipophillic (ie solutble in oil) it will be able to diffuse across the blood brain barrier.  Hence, the majority of psychoactive drugs--which need to cross the blood brain barrier to exert their effects on the CNS--are lipophillic.  Since they are foreign elements that the body is not specifically geared to allow, they can only reach the brain by simple diffusion through the membranes.  Steroid hormones, generally derived from highly lipophilic cholesterol, are likewise able to freely diffuse across the cell membranes without needing protection from hydrophobic interiors of the lipid bilayer membranes.\n\nFacilitated diffusion is when the diffusion down the chemical gradient is made possible by the existance of channels that will allow molecules that cannot cross the membranes alone (either due to size or due to thermodynamically unfavorable interactions with the membrane interior) to cross.  An example is the potassium leak channel in the neuron.  The potassium ion is charged, and hence is only souble in polar solvents like water--it is very thermodynamically unfavorable for it to interface directly with the lipids in the membrane interior.  So channles, with a hydrophilic core allow the ions to diffuse out of the cell while side-stepping thermodynamic issues.\n\nBoth of these types of diffusion need to be distinguished from active transport, where a chemical moves UP a gradient by being coupled with a spontaneous, energy releasing activity (like the hydrolysis of ATP).
1004078
Diffusion is the flow of particles down the concentration gradient. Meaning that particles are flowing from an area of high concentration to an area of low concentration. Two examples are this occuring around your house are\n1. when you take a bubble bath. Even if you were to pour the bubbles in after the water stopped runnning the bubble mixture would still spread evenly throughout the water by simple diffusion.\n2. when you light a scented cande. The scent travels throughout the whole house because it travels from an area of high concentration (right above the candle) to the rest of the areas around the house that have low concentrations of the scent.\nGood? next time do your homework yourself :)