what is the function of a channel protein?
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Transmembrane proteins form channels through the lipid bilayer.\nThere are different sorts of channels, ion channels for example.\nIn the case of ions, they would not normally be able to cross the membrane, a channel protein (plus associated mechanisms) make it possible.
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1. I guess You think about the nexuses. Its a metabolic and ionic connection of cells in form of ionic channels (built by proteins called conexones or conexone proteins).It provides rapid transport of membrane polarization changes. Its a form of electric synapses.\n2.I guess You think about the lysosomes. They're created by Golgi's Apart ('Trans" side).Lysosomic enzymes are created by Rough Endoplasmic Reticulum and GA. Lysosomical endoenvironment's pH is about 5. Function- to connect with endosomes, phagosomes and autophagosomes and to catalyze and guide analysis reaction (some kinds of digestive reactions).
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LIPIDS:\nOne function for Lipids is that of Energy storage. Lipids contain a lot of calories in a small space. Since Lipids are generally insoluble in polar substances such as water, they are stored in special ways in you body's cells. Lipids can also function as structural components in the cell. Phospholipids are the major building blocks of cell membranes. Lipids are also used as hormones that play roles in regulating our Physiology (metabolism). \n\nCARBOHYDRATES:\nThe main function of carbohydrates is to provide energy, but they also play an important role in the structure and function of the body organs and nerve cells \n\nPROTEINS:\nProteins have many functions. They serve as enzymatic catalysts, are used as transport molecules (hemoglobin transports oxygen) and storage molecules (iron is stored in the liver as a complex with the protein ferritin); they are used in movement (proteins are the major component of muscles); they are needed for mechanical support (skin and bone contain collagen-a fibrous protein); they mediate cell responses (rhodopsin is a protein in the eye which is used for  vision); antibody proteins are needed for immune protection; control of growth and cell differentiation uses proteins (hormones).  These are just a few examples of the many, many functions of proteins.
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I hope i understand your question-\nForces: Osmosis = 1\n              Facaltative diffution =2\n               \n2.Thier is the NA/K pump in cell membranes that control water level\n1.The albumin in tissues that regulates homeostasis\n1 and 2.There is the CL pump that also regulates water in the cell membrane. \nThink those are the main ones
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The plasma membrane or the cell membrane is semi-permeable.Its function is to regulate the exchange of materials between the cytoplasm and extracellular fluid.
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Proteins are large molecules that are made from amino acids, which are small molecules.
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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.
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There are potassium ion channel pumps on the cell membrane. This pump pumps out CL ions and bring in K+ ions. It  goes against the flow of diffusion, so energy is needed. When an action potential is created, it oppens Cl- gated channels which, due to the differnt concentrations (more on the outside) the CL rushes back in, creating a change in cell voltage.
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"Aquaporin" is a class of molecules, so which one are you looking for the formula for?  And what possible reason might you have for wanting to know? LOL\n\nHere's a link that explains what they are, (they are basically conglomerate protein molecules) and as you can see the 'chemical formula' might be somewhat clumsy and unenlightening!
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Abstract. \n...membranes, microvilli, and membrane projections, and act as crosslinkers between the actin cytoskeleton and proteins of the cell surface...\nhttp://147.52.72.117/IJO/2002/volume21/number5/935-940.pdf \n\n \nforthcoming meetings\nAim: to learn techniques commonly used to analyse signal transduction ... and cell adhesion (cytoskeleton, cell adhesion proteins, extracellular\nhttp://www.usgeb.ch/skmb2005.html \n\n \nBTO\n...and function of proteins, methods of ... Cytoskeleton and cell motility. ... Describe and use structure determination techniques to analyse\nhttp://www.bto.ed.ac.uk/courses/year1/index0506.phtml \n\n \nRandall Division o f Cell and Molecular Biophysics\n...actin cytoskeleton during migration. I use a number of different advanced imaging techniques to analyse ... analysis of interacting proteins by\nhttp://www.kcl.ac.uk/depsta/biomedical/randall/mparsons.html \n\n \nGlossaire (ULg)\nAnkyrins. A family of membrane-associated proteins responsible for the attachment of the cytoskeleton. Note: membrane proteins \nhttp://www.ebm.lib.ulg.ac.be/prostate/gloss.htm \n\n \nThe role of the axolemma in the initiation of traumatically induced...\n...proteins. Transmembrane proteins such ... matrix to the cytoskeleton via the ... Biophysical investigations have used novel techniques to\nhttp://www.jnnp.com/cgi/content/full/64/3/285 \n\n \nThe tiniest parts of \n...are as dispart as the techniques and ... natural science, is to analyse the ... energy or information, signal transducers, cytoskeleton...\nhttp://www.uni-leipzig.de/~philos/psarros/preprints/the_tiniest_parts_of.html \n\n \nGenome Biology | Full text | Analysis and functional classification\n...as well as the development of new techniques for ... genes encoding cytoskeleton proteins (such as myosin, actin, UNC-87, troponin T) and\nhttp://genomebiology.com/2003/4/4/R26 \n\n \nStudy Abroad 2004 INTRODUCTION 2 Deakin University's unique Study \nUnit Handbook GUIDE TO UNIT DESCRIPTIONS ACD206/306 Dance Production and Analysis Second semester, 1 credit point Prerequisite ACD203 or Level One \nhttp://www.deakin.edu.au/international/Documents/Brochures/SAHandbook.pdf \n\n \nAdrian Harwood\n...genetic, biochemical and cell biological techniques to analyse the ... has both a cytoskeleton and a network ... SH2 domain proteins,\nhttp://www.ucl.ac.uk/LMCB/pages/harwood.html
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To get the right answer you need to ask the right question. \n\nWhat you are looking for is tools and techniques for Protein Structure Modeling. \n\nJust type "Protein Structure Modeling" in Google and you should get a bazillion hits!\n\nHere are a few sites to get you going anyway:
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Entire courses and course of study are devoted to this question.  But here are some examples:\n\nSignal Transduction Pathways - This is a really broad category.  Cells communicate with the extracellular "milieu" using surface receptors.  When a certain signal molecule binds to the receptor, this initiates a signal cascade.  At the end of many of these cascades are transcription factors and regulatory pathways that can initiate or block transcription.  So the presence or absence of certain substances results in certain molecules that initiate transcription of certain genes.\n\nRhythms - Some proteins can interact with other proteins and regulate each others presence or absence.  This is particularly important for circadian rhythms and regulation of the cell cycle.  One protein initiates transcription of the another protein, and this other protein in turn down regulates transcription of the original protein.  The other protein eventually degrades, the the original protein's function returns.   \n\nIn essence, cells can sense what they need through proteins.  These proteins can signal other proteins which can eventually lead to the initiation or blocking of transcription. \n\nHope that helps!
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Glucose, sodium ions and choride ions are just a few examples of molecules and ions that must efficently get across the plasma membrane but to which the lipid bilayer of the membrane is virtually impermiable. Their transport must therefore be "facilitated" by proteins that span the membrane and provide an alternative route or bypass. Facilitated diffusion is the name given this process. It is similar to simple diffusion in the sense that it does not require expenditure of metabolic energy and transport is again down an electrochemical gradient. \n\nTwo major groups of integral membrane proteins are involved in facilitated diffusion: \n\nCarrier proteins(also known as permeases or transporters) bind a specific type of solute and are thereby induced to undergo a series of conformational changes which has the effect of carrying the solute to the other side of the membrane. The carrier then discharges the solute and, through another conformational change, reorients in the membrane to its original state. Typically, a given carrier will transport only a small group of related molecules.\n\nSome important and illustrative groups of transporters are: \nCertain of the hexose transporters, which transport glucose and similar monosaccharides into and out of cells.\n \nBand 3, the anion transporter, which facilitates transport of bicarbonate and chloride ions \n\n\nIon Channels do not really bind the solute, but are like hydrophilic pores through the membrane that open and allow certain types of solutes, usually inorganic ions, to pass through. In general, channels are quite specific for the type of solute they will transport and transport through channels is quite a bit faster than by carrier proteins. Additionally, many channels contain a "gate" which is functions to control the channel's permiability. When the gate is open, the channel transports, and when the gate is closed, the channel is closed. Such gates can be controlled either by voltage across the membrane (voltage-gated channels) or have a binding site for a ligand which, when bound, causes the channels to open (ligand-gated channels).\n\nIon channels allow currents the be carried across the membrane and are thus of particular importance in the physiology of excitable cells like neurons and muscle cells.
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Chaperone proteins help newly made protein to fold into the appropriate secondary and tertiary structures (since primary structure is already created during translation, well there are some post tranlational modifications). It also prevents the protein from escaping into the cytoplasm, and prevents it from be degraded.
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Linker or adapter proteins provide mechanisms through which  effector proteins (which bind to other proteins and alter their activities) can be amplified and/or regulated.\n\nI think, anyway. Could be wrong.
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Proteins can not penetrate plasma membranes\nCyclic AMP (mediates neurotransmitters)\nHormone (first messenger) binds to receptor\nReceptor binds G-protein\nG-protein binds GTP, releasing GDP (has GTPase)\nActivated G-protein moves along membrane binds to Adenalyte cyclase,\nhydrolyzes it’s bound GTP to GDP.\ncAMP generated from ATP (secondary messenger)\nCyclic AMP (cAMP) diffuses throughout cell, triggering protein kinases\n(enzymes)\nExample: Epinephrine (adrenaline) on fat cell-break down glycogen and fat.\nPhosphodiesterase (intercellular enzyme) degrades cAMP\nImplications\nMultiplier effect: 1 Adenylate cyclase: ?? cAMP\nKinase catalyzes hundreds of reactions\nSingle hormone may catalyze millions of product molecules\nSequence regulated by:\nTarget cell type, specific protein kinases, and the initiating hormone\nSecondary messenger system: The PIP-Calcium signal mechanism\nSome hormones (e.g. epinephrine) mediated by Calcium, not cAMP.\nHormone binds to receptor\nG protein activated as GTP binds, displacing GDP\nG protein binds to and activates a membrane bound phospholipase, and\ninactivates\nPhospholipase splits PIP2 into IP3 and diacylglycerol (secondary messengers)\nPIP2 : phosphatidyl inositol biphosphate; IP3: inositol triphosphate\nIP3: Calcium from ER (endoplasmic reticulum)\nDiacylglycerol: Protein kinases\nCa2+: alters plasma membrane ion channels and also binds to Calmodulin, which\namplifies cellular response (decreases the energy of activation)\n\nalso see:
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This lacks an actual question, but I see what your teacher is aiming at. \nHint: what is the main function of the large intestin? What is reabsorbed there that you wouldn't especially need in aquatic environments?