What is the relationship between of surface area to rate of transport of materials in and out of a cell?
349062
The greater the surface area, the faster the rate of transport.  Imagine it, it's like all trying to get on a bus with only one small door, compared with opening up a whole side.
973307
Because cells must keep an optimal surface area:volume ratio in order to be able to receive food and transport it throughout the cell effeciently. If they grew too large, they would starve and die.
861890
Molecules go in and out from the cell at same rate thats is why it is called EQUILIBIRIUM
802415
Normally the particles (let us call them solutes for now) move from where they are more in concentration to where there are less solute particles in solution. This is just diffusion. This is some kind of standard stuff ALL THINGS MOVE FROM HEIGHTS to DEPTHS!! no more energy is required for this.\n\nBUT there are many more things in life which need to go against this principle and this is where the cell needs to spend energy ATP may be.. So when some particles are actively transported what it means is that energy is spent to do something against the concentration gradient. If it wants to bring more K+ ions into a cell which already has heaps when compared to the outside it needs to spend energy, There are many reasons why it may want to do it.. ... may be it wants to accumulate stuff for later (store glucose)..\n\n ..\nhope that helps,,,
780024
Diffusion is the normal migration of molecules from an area of higher concentration to an area of lower concentration until and equal concentration is achieved.  Everything in nature does this.\nExample-open a bottle of perfume then pretty soon the person in the next room can smell it and so on.\nOsmosis is diffusion or the movement of water across a semipermeable membrane( a cell membrane that lets some stuff in and keeps others out.).  It can go in or out of the cell based on the concentration.  Water is a common carrier molecule for other substances.\nThus diffusion and osmosis are the same except osmosis must have a membrane crossed.
941524
Gee...broad question...depends what ur transporting.\ne.g. for gases u need a semi-permeable membrane, a thin membrane, a gradient, a moist/mucus surface
467240
Given that a certain type of molecule is small enough to permeate through the cell membrane, the most important factor influencing the rate of diffusion is the concentration gradient.  This is simply the difference in concentration levels of the substance between the outside and the inside of the cell.  The larger the difference in concentrations, the greater the rate of diffusion.
855397
Not sure what you mean... \nAn example of simple diffusion is that of steroid hormones which diffuse readily through the cell mebrane and reach their target molecules within the cell.\n\nFacilitated diffusion you have for example for the uptake of many hydrophilic/charged nutrients from the blood. The concentration of the nutrient is higher on the outside of the cell, yet it cannot simply diffuse through the membrane; it needs the help of transport proteins.\n\nActive transport means that the cell needs to import something uphill its gradient, using energy. The most profound example is the Na+/K+  ATPase which pumps Na+ out of the cell and K+ into the cell using ATP (both Na+ export and K+ import are uphill processes).\n\nA beautiful combination of passive and active transport is seen in the intenstinal epithelial cells. The concentration of glucose in the gut is lower than inside the cell. So the human body needs to consume energy and actively import glucose. This happens via a symporter that imports Na+ together with glucose. The import of Na+ is downhill so it releases energy which is used for the uptake of glucose. Once the glucose is inside the epithelial cell it will be passively exported to go to to the bloodstream.
844758
Using the Michaelis-Menten equation.\n\nMore details on teh attached link\n\nhttp://www.le.ac.uk/by/teach/biochemweb/tutorials/michment2print.html\n\nGood luck
377572
Substances could move across the cell membrane by either passive or active transport. Passive transport happens with kinetic energy and along a concentration gradient (difference in concentration of a substance).Passive transport includes diffusion, osmosis and facilitated diffusion. Oxygen and carbon dioxide are examples of substances that diffuse.Water will go through by osmosis and glucose is a substance that uses facilitated diffusion.\nActive transport needs energy in the form of ATP and happens against a concentration gradient. Active transport includes endocytosis and exocytosis.It involves the passage in or out of larger molecules.
1146467
As cells grow the surface area/volume ratio goes down.  This inhibits their ability to uptake nutrients.
612940
It would depend on several factors. Small, uncharged molecules can pass through the cell membrane through diffusion. When it is water, it is called osmosis. Diffusion can only occur into the cell when the concentration of the substance is greater outside the cell than within it, and likewise only out of the cell when the concetration is greater inside the cell than outside. This is called the concentration gradient.\n\nWhen the molecule is charged or is large (such as a chlorine ion or a lactose molecule), it requires active transport by carrier proteins. There are also carrier proteins that help to transport against the concentration gradient.\n\n[Edit] \nAfter thinking for a bit, I believe it would be pertinent to include something about the more complex methods of active transport.\n\nThere are two "directions" of the complex forms of active transport: in (endocytosis) and out (exocytosis).\n\nExocytosis is when a vesicle, after being released from the Golgi complex, fuses to the cell membrane, releasing the contents.\n\nEndocytosis is done by three main means: Phagocytosis, Pinocytosis, and Receptor-Mediated Endocytosis.\n\nPhagocytosis is the process of enveloping a large particle, such as how many unicellular organisms "eat" other organisms. The large particle comes in contact with the cell membrane, stimulating the formation of a vesicle. This vesicle then enters the cell and depending on the contents may fuse with a lysosome to help to digest it.\n\nPinocytosis also forms a vesicle, but differs from phagocytosis because it forms a much smaller vesicle.\n\nReceptor-mediated endocytosis is when particles that cannot normally enter the cell bond to receptor proteins embedded in the cell membrane. These proteins then congregate and form a vesicle. \n\nIn all forms of endocytosis and exocytosis, ATP is required for energy.
708263
Suface Area and Transport Distance. I Strongly Suspect the Reason Prokaryotic/Eukaryotic Cells Are the Size they Are is Because of Evolutionary Optimization by Natural Selection.
855791
There are a lot of items or writting related to these words. Permeability  is a measure of the ability of a material to transmit fluids. \n\nAbsorption, in chemistry, is a physical or chemical phenomenon or a process in which atoms, molecules, or ions enter some bulk phase - gas, liquid or solid material. \n\nthese two did not related to each other
533289
The rate of diffusion in a material is determined by \nthe density of the  material\nporosity present in the material\nthickness of the material\nvelocity at which the diffusant traveling towards the material.\n\nIf the diffusant is liquid, the viscosity of the liquid.
703068
Hey we were learning about that in school this week. anyway Active transport is the "movement of materials through a cell membrane using energy"\nand Diffusion is "the process by which molecules tend to move from a area of higher concentration to an area of lower concentration\n\nactually diffusion is a form of active transport so really that is the similarity because its like parts of a whole((sorry if this was confusing))\n\n~*~*~*~*~*~*~*~~*~*~*~*~**~*~*~*~*~*~*~\nMy name is Brittany ((LoL i knrew it would be confusing))\n~*~*~*~*~**~*~*~*~*~**~*~*~*~*~**~*~*~\nim in 7th too. ((if its not too much can you e~mail me?))\n~*~*~*~*~**~*~*~*~*~*\nalright
769834
100 and 1000, respectively. Surface area is proportional to the square of the radius, so if a cell's surface ares is 4πr², then the surface are of a cell with 10 times the radius is 4π(10r)² = 100(4πr²). Similar logic applies to volume (which is proportional to the cube of the radius).