In reference to cell biology, what exactly is membrane recycling and how does it work?
914562
Membrane recycling is the process where the cell moves around its membrane and phospholipid molecules where it needs it most. There are both endocytosis and exocytosis which move the membrane (phospholipid bilayer) around. In endocytosis, large particles that can't diffuse through the membrane bind to receptor proteins on the surface of membrane. Then that area caves in when the ligand (whatever the molecules were) binds and pinches of forming a complete circle(sac) with the molecules ont the inside. These sacs called vesicles now move around inside the cell and may find places such as the Golgi Apparatus (which is also made of membrane) and may attach there. that moves membrane AWAY from the outer cell membrane to the inside. In exocytosis, membrane sacs (vesicles) are prepared in the Golgi Apparatus or other membrane oragnelles (in the same fahsion as they were in exocytosis except in different location) and they travel to the outer cell membrane. Here the vesicle slowly fuses with the plasma membrane (outer cell) and secretes the inside. Now the Phospholipid molecules that previously formed the vesicle noow becomes part of the plasma membrane. Sometimes blank or empty vesicles are sent ot plasma membran in order to enlargen it whether secretion takes place. This also applys to endocytosis.\n\nHope this helps and Good luck
54079
There are numerous proteins embedded in the lipid bilayer of the cell membrane; some, like adrenergic receptors and porins (channels things move through), perforate the membrane; others protrude out one part, not another.  Others, like the G-proteins and the enzymes that phosphorlate and dephosphorylate other membrane proteins, stay pretty much entirely in the membrane.\nMany of the proteins, such as receptors and porins, move fairly freely; others, particularly the proteins that cause adherence between cells, are fixed in place.\nI guess the best answer is that the arrangement of the proteins in the cell membrane is complex, and for many proteins, ever changing, but for others, static.  It's not nearly as simple as it looks.  For instance, in modeling the large membrane proteins, the cell membrane is effectively a gas in two of three dimensions, and a solid in the third...  Go figure.
613788
The endomembrane system is the system of internal membranes within eukaryotic cells that divide the cell into functional and structural compartments, or organelles. Prokaryotes do not have an endomembrane system and thus lack most organelles.\n\nThe endomembrane system also provides a transport system, for moving molecules through the interior of the cell, as well as interactive surfaces for lipid and protein synthesis. The membranes that make up the endomembrane system are made of a lipid bilayer, with proteins attached to either side or traversing them.\n\nThe following organelles are part of the endomembrane system:\n\n    * The plasma membrane is a phospholipid bilayer membrane that separates the cell from its environment and regulates the transport of molecules and signals into and out of the cell.\n    * The nuclear envelope is the membrane around the nucleus of the cell.\n    * The endoplasmic reticulum is a synthesis and transport organelle [the endoplasmic reticulum is an extension of the nuclear envelope].\n    * The Golgi apparatus acts as the packaging and delivery system for molecules.\n    * Lysosomes are the "digestive" units of the cell. They utilize enzymes to break down macromolecules and also act as a waste disposal system.\n    * Vacuoles act as storage units in some cells.\n    * Vesicles are small membrane-enclosed transport units that can transfer molecules between different compartments.
233869
You're probably referring to the plasma membrane. The interior is hydrophobic, while the exterior is hydrophillic. The phospholipids can translocate horizontally within the bilayer, but can't cross from one layer to the other. So, the membrane behaves like a fluid.  See MIT's website for more info. the link is below
694748
Receptor mediated endocytosis is a process by which cells internalize molecules or viruses. As its name implies, it depends on the interaction of that molecule with a specific binding protein in the cell membrane called a receptor.
791085
The cell membrane is a phospholipid bilayer, meaning there are two chains. Each chain has a serious of long non-polar tails (hydrophobic, hate water, non-permeable to polar molecules) with polar heads (hydrophilic, love water, permeable to polar molecules). The polar heads are on the outside of the membrane and the non-polar tails face the middle of the membrane. This structure prevents molecules from freely moving across the membrane. Embedded within the membrane are protein channels that are designed to specifically allow certain molecules through. Some of these channels open randomly, others require some kind of signal. They are selective by allowing molecules of certain size and/or charge (positive or negative) cross the membrane, also keeping in mind concentration gradients (molecules will move down their gradients). In some cases, molecules move against their gradients, but require energy to do it.
736186
Facilitated diffusion (or transport) is the diffusion across a membrane which is aided by a membrane protein usually by a channel or pore this allows molecules that cannot pass through the lipid bilayer to enter the cell. The process still occurs down a concentration gradient, like normal diffusion and it requires no energy unlike active transport. For more information you could try looking up passive transport.\n\nI hope this helps
967476
CELL MEMBRANE IS THE BOUNDARY BETWEEN IT'S CELL AND IT ENVIRONMENT
980296
The cell may become too large to take in enough food and to remove enough wastes.  Food intake and waste removal are processes that can happen only at the cell membrane.  However, as a cell becomes larger, the ratio of its surface area to its volume decreases.  This means that a larger cell will eventually have metabolic requirements due to its size that cannot be met by the limited size of the cell membrane.  Some cells, such as nerve cells, become very long and thin in order to achieve large sizes despite this limitation.
359728
Cell membranes are made of lipid bilayers, meaning it is made of a type of fat.  KOH is a strong base that is capable of reacting with the fat in the same reaction that produces soap.  This destroys the lipid bilayer
613363
because your cells are trying to maintain homeostasis- in order to work properly your cells need water to use aerobic respiration.( this is the most efficient way to produce energy) To get this water the cells use a method of transportation that allows water to move in and out of the cell membrane. your prune fingers are just the cells filling with water to promote chemical reactions.
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.
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
760480
Molecules found on the outside of the cell are endocytosed into vesicles and fuse with endosomes (which are just a collection of vesicles) once an endosome recieves the special digestive enzymes from the Golgi it becomes a lysosome.\n\nSo overall yup lysosomes are just a special vesicle!
778955
The cell membrane is a lipid bilayer made from phospholipids.  As a lipid, it is permeable to other lipids (e.g. steroid hormones) but not to polar molecules (e.g. potassium or glucose).  Polar molecules require various types of membrane proteins (e.g. potassium channels) or endocytosis (glucose) for absorption into the cell.  \n\nHope this is helpful for you.  Best wishes and good luck.
78375
Simply stated, RO is a membrane process, which removes both organic molecules and salt ions from a solution (typically water). The membrane sieves organic molecules and repels salt ions while passing pure water through the micropores in its surface.\n\nThe driving force behind RO is pressure, which is typically supplied by a centrifugal pump. This pressure is needed to overcome the inherent osmotic pressure of the solution and to supply enough energy to force water through membrane pores which are only about 5 angstroms in diameter (by comparison, a human hair has a diameter of about 500,000 angstroms).\n\nThe basic components of an RO system are the prefilter, a pump, and sepralators (spiral-wound membrane elements). The sepralators are placed in stainless steel or PVC housings, which are then manifolded together.\n\nRO systems operate in a crossflow mode whereby a single stream is fed into the RO and flows across the membrane surface. Two streams exit--the permeate and the concentrate. The permeate stream contains the water which passes through the membrane and is purified. The concentrate stream contains the water, salt ions, and organic molecules that do not pass through the membrane; the concentrate is typically plumbed to drain.\n\nThe advantage of operating in the crossflow mode is that it minimizes plugging of the very small membrane pores. However, as a result of crossflow operation, only a percentage of the feed is collected as permeate. This ratio of the permeate to the feed is called the "recovery" of the RO. Though it would seem that one would want to have as high a recovery as possible, there is a trade off--the higher the recovery goes, the poorer the permeate quality becomes. In practice, the majority of RO systems producing less than 15,000 gallons of permeate per day operate at 33% or 50% recovery.
1005164
Cells produce water and carbon dioxide as by-products of metabolic breakdown of sugars, fats, and proteins. Chemical groups such as nitrogen, sulfur, and phosphorous must be stripped, from the large molecules to which they were formerly attached, as part of preparing them for energy conversion. The continuous production of metabolic wastes establishes a steep concentration gradient across the plasma membrane, causing wastes to diffuse out of cells and into the extracellular fluid.\n\nSingle-celled organisms have most of their wastes diffuse out into the outside environment. Multicellular organisms, and animals in particular, must have a specialized organ system to concentrate and remove wastes from the interstitial fluid into the blood capillaries and eventually deposit that material at a collection point for removal entirely from the body.