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Topic: Ion gradient

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	RTFTechnologies Ion Gradient Formation in Lithium Cells
		During current generation, an ion gradient forms in a lithium cell since the rate of ion transport away from the anode and cathode of the cell is less than the rate at which the ions accumulate at the originating electrode.
		The increasing viscosity of the electrolyte decreased ion mobility and the rate of ion diffusion of the cell causing areas of higher ion density localized at the surfaces of the anode and cathode.
		The increasing viscosity of the electrolyte decreased ion mobility and the rate of ion diffusion in the cell causing areas of high ion concentration localized at the surfaces of the anode and cathode.
	www.rtftechnologies.org /chemtech/licell.htm (3311 words)

	Intracellular Ion Environment and Membrane Electric Potential
		The movement of ions across the plasma membrane and organelle membranes is mediated by several types of transport proteins: all symporters and certain antiporters cotransport ions simultaneously along with specific small molecules, whereas ion channels, ion pumps, and some antiporters transport only ions.
		In all cases, the rate and extent of ion transport across membranes is influenced not only by the ion concentrations on the two sides of the membrane but also by the voltage (i.e., the electric potential) that exists across the membrane.
		However, continued right-to-left movement of the Na ions eventually is inhibited by the mutual repulsion between the excess positive (Na) charges accumulated on the left side of the membrane and by the attraction of Na ions to the excess negative charges built up on the right side.
	www.ncbi.nlm.nih.gov /books/bv.fcgi?rid=mcb.section.4055 (2011 words)

	Electrochemical gradient - Wikipedia, the free encyclopedia
		Second, a chemical component is caused by a differential concentration of ions across the membrane.
		Electrochemical gradients are analogous to hydroelectric dams and equivalent to the water pressure across the dam.
		Cotransport of ions by symporters and antiporter carriers are common to actively move ions across biological membranes.
	en.wikipedia.org /wiki/Electrochemical_gradient (1011 words)

	cellulartransport
		Ion channels are transmembrane proteins that allow ions to move across membranes with their concentration gradient at high rates.
		The gradient continues to favor input of the sugar because the previous molecules have been slightly altered, and the phosphorylated glucose is not shipped out.
		The movement of 2 sodium ions into the cytoplasm, which is lesser in sodium ion concentration, changes the conformation of the transport protein, and glucose is released.
	members.tripod.com /andykahn/cellulartransport.htm (1617 words)

	Bioelectricity of cell membranes
		Any ion that forms an ion gradient across a membrane, and that is permeable contributes to the actual membrane potential.
		While ion gradients are the result of pumps that move ions across membranes in an ATP dependent fashion (e.g.
		R is the gas constant, T the actual temperature, z the number of charges of the ion species, F the Faraday constant, and C(out) and C(in) the extracellular and intracellular concentrations of the ion.
	www.whatislife.com /reader2/membrane_bioelectricity.htm (6367 words)

	Gradient - Wikipedia, the free encyclopedia
		See image gradient for the term used in graphics; slope for the measure of steepness of a straight line, and grade for the grade or gradient of roads and other geographic features.
		In vector calculus, the gradient of a scalar field is a vector field which points in the direction of the greatest rate of increase of the scalar field, and whose magnitude is the greatest rate of change.
		The gradient of H at a point is in the direction of the steepest slope or grade at that point.
	en.wikipedia.org /wiki/Gradient (602 words)

	Brain and Behavior (IPHY 3730), University of Colorado at Boulder
		Membrane proteins in a nerve cell have a number of specific functions, such as permitting selective passive of an ion (=ion channel), moving an ion against a concentration gradient (=ion pump), or acting as a receptor which communicates information about events in the immediate environment.
		Ion distribution across the plasma membrane is based largely on physical laws involving ion charge and concentration.
		1) act as ion channels, as in nerve function 2) act as a receptor for a hormone/neurotransmitter 3) are carrier molecules for specific substances 4) docking proteins for vesicle identification 5) glycoproteins are markers for cell-cell identification.
	www.colorado.edu /intphys/Class/IPHY3730/03plasmamembrane.html (1826 words)

	Re: How does the brain produce electricity?
		The electro-chemical gradient is the basis of nerve cell signalling, because it is basically potential energy.
		One consequence of making chemical gradients with charged particles, is that the concentration gradient results in a charge gradient with one side of the membrane becoming more positively charged and the other side becoming negatively charged.
		Thus, the ion pumps behave as a constant current source by creating the ion gradients across the membrane, a process requiring large amounts of energy in the form of ATP.
	www.madsci.org /posts/archives/dec97/880395992.Ns.r.html (1001 words)

	lc20elc1
		Ions are attracted by opposite charge; repelled by the same charge.
		At any given time, a fraction of these transported ions are leaking back across the membrane, passing down their concentration gradients through their specific ion channels.
		For any given ion concentration gradient, the term equilibrium potential refers to that (equal and opposite) electrical potential which is sufficient to counterbalance diffusion and maintain the equilibrium state, i.e.
	www.sbs.utexas.edu /shankland/lc20elc1.htm (1126 words)

	Lecture 7
		Cells maintain a hydrogen ion gradient across the plasma membrane and use this gradient to power a number of cellular processes, particularly ion uptake.
		Ions are now in contact with the cell membrane, and can be taken up into the symplast of the root cortex.
		Ions are then passed on to the parenchyma of the stele.
	nas.cl.uh.edu /novotny/pph07.htm (1057 words)

	Generation of resting membrane potential -- Wright 28 (4): 139 -- Advances in Physiology Education (Site not responding. Last check: 2007-11-04)
		ion transport is beyond the scope of this presentation).
		ions, is the basis for generation of transmembrane voltage differences.
		ion, as is evident from inspection of the Goldman equation.
	advan.physiology.org /cgi/content/full/28/4/139 (2563 words)

	Potassium Ion Channels - Rod MacKinnon
		occurs as ion enters filter [see figure], where only half of the remaining six are occupied at any one time.
		arrows indicate ion shifts that are linked directly to concerted ion entry into and exit from the pore.
		ions are numbered to indicate the location of binding sites in the filter; position 1 is closest to the
	fig.cox.miami.edu /~cmallery/255/255ion/K_channel.htm (354 words)

	Transporters
		For an ion, G is determined by both the concentration gradient AND the electrical gradient (includes the ion charge and the membrane potential)=electrochemical potential
		The carrier protein binds an ion on the inside of the cell; energy from ATP is used to drive a change in conformation (shape) of the carrier protein-exposing the ion to the outside of the cell; the ion is released from the binding site to the outside
		In animals, the Na gradient generated by the Na ATPase is used to drive the active transport uptake of nutrients, such as glucose and amino acids and to drive the active transport of H
	www.esf.edu /efb/course/EFB325/lectures/transpor.htm (916 words)

	TRANSPORT MECHANISMS
		Ion transport (for the most part ion transport is under the same principles as discussed for facilitated diffusion and the to be discussed phenomenon of active transport)
		(n is the charge of the ion, T absolute temperature, R is the gas constant, and F is the Faraday constant.) The membrane voltage potential is proportional to the natural log of the ion concentration gradient.
		The concentration gradient and the charge gradient favors the diffusion of the Na+ back into the cell, but it can not pass through the phospholipid bilayer because of the charge on the Na+.
	www.mrs.umn.edu /~goochv/CellBio/lectures/transport/transport.html (2232 words)

	Columbia Linear Machine (CLM) (Site not responding. Last check: 2007-11-04)
		An ICRF mesh in the transistion region ensures heating of ions in the radial center of the plasma, hence producing an ion temperature gradient, facilitating the studies of the Ion Temperature Gradient (ITG) instabilities.
		A small ion beam source (IBS) is located at the end of the experimental region.
		This ion beam (also configurable as an electron beam) is used as a remote suppressor for feedback control studies.
	www.ap.columbia.edu /apam/plasma/clm.html (469 words)

	Properties of the Stochastic Energization-Relaxation Channel Model for Vectorial Ion Transport -- Muneyuki and Fukami ... (Site not responding. Last check: 2007-11-04)
		A model for the primary active transport by an ion pump protein is proposed.
		The rate constant of ion transfer between the adjacent binding sites is defined by the height of the potential barrier.
		Hammes, G. Unifying concept for the coupling between ion pumping and ATP hydrolysis or synthesis.
	www.biophysj.org /cgi/content/full/78/3/1166 (4964 words)

	COMPONENTS OF THE HPLC SYSTEM \| Resources for Analytical Chemistry and Seperation Science
		There are two options for gradient mobile phase operation - high pressure mixing which requires a pump for each solvent, and, low pressure mixing which requires only one pump (placed after a proportioning valve assembly that contains a multi-solvent inlet port).
		Because of its extreme sensitivity to the mobile phase, this detector may not be used without adequate pulse-damping within the LC pump, nor is it suitable for gradient applications because of the changing mobile phase composition.
		The addition of a chemical suppressor between the column and conductivity detector serves to reduce the eluant conductivity, allowing the use of gradient elution and the determination of ppb levels with minimum baseline drift.
	www.laballiance.com /la_info/support/hplc4.htm (1524 words)

	BCH 4053 Biochemistry I (Site not responding. Last check: 2007-11-04)
		These ions are transported in opposite directions at the same time, thus, the transport is electrically neutral.
		ions is driven simply by relative concentration gradients of these ions across the membrane.
		Use of such an existing ion gradient by another transport process is referred to as a secondary active transport process.
	wine1.sb.fsu.edu /BCH4053/Lecture16/Lecture16.htm (1984 words)

	Wendell Horton: Current Abstracts
		The large ion gyroradius conductance of the quasineutral sheet produced the energization of the central plasma sheet (CPS) while the unloading is triggered when the net geotail current or current density exceeds a critical value.
		In this work a new model of the ion thermal transport, based on the long wave-length behavior of the ion-temperature-gradient-driven turbulence, is introduced.
		A relevant property of the model is that the thermal conductivities grow with minor radius, as a consequence of the positive dependence of the correlation length and of the inverse of the correlation time on the ion temperature gradient.
	www.ph.utexas.edu /dept/research/horton/abstracts.html (1036 words)

	[No title]
		Answer: The Na+ and K+ gradients collapse in the absence of pump activity due to ions leaking across the plasma membrane, at a rate proportional to PNa and PK.
		Ion flow through these channels is coupled to the membrane potential and the concentration gradient.
		The activity of the Na+/H+ exchange is decreased due to the increased lumenal [H+] and Cl- is unable to enter the cell due to the absence of the exchanger.
	cim.ucdavis.edu /masters/sessions2002/Session5_ICA.doc (3180 words)

	Dr. Dale Dubin - The MD Site -
		but you may be a little uncertain about the function of ion channels, ion pumps, and ion exchangers of cardiac cells.
		The controlled movement of three little ions is the basis of cardiac physiology.
		Ion Adventure in the Heartland is brief in text, yet every page is profusely illustrated in three-dimensionally-rendered, color illustrations; with a learning system that reinforces your comprehension.
	www.themdsite.com /ion.cfm (1258 words)

	separationsNOW..com: Ion Chromatography Ezine
		This review focuses on current developments in monolithic stationary phases for the fast analysis of inorganic ions and other small molecules in ion chromatography and capillary electrochromatography, concentrating on the properties of organic, polymeric monolithic materials.
		In this paper the compound-specific determination of stable carbon isotopes of organic acids in gaseous and aerosol phases, as well as of water-soluble organic carbon, was effected by sampled with a wet effluent diffusion denuder/aerosol collector coupled to an ion chromatography system which allows fraction collection of the organic acids for subsequent isotope analysis.
		Researchers have investigated the persistence of four commonly used pesticides in water from nursery collection ponds using a combination of ion chromatography, gas chromatography and filtration.
	www.separationsnow.com /coi/rss/Feature_2_5.xml (752 words)

	Bioenergetic Aspects of Halophilism -- Oren 63 (2): 334 -- Microbiology and Molecular Biology Reviews (Site not responding. Last check: 2007-11-04)
		of an inorganic ion gradient are energetically costly.
		ion for every two protons entering the cell (94, 117).
		Isolation and characterization of salt-sensitive mutants of the moderate halophile Halomonas elongata and cloning of the ectoine synthesis genes.
	mmbr.asm.org /cgi/content/full/63/2/334 (9705 words)

	Nonlinear Ion-Mixing-Mode Particle Transport in the Dissipative Trapped Electron Regime -- from Mathematica Information ...
		The renormalized dissipative nonadiabatic trapped electron phase-space density response is derived and used, along with an ansatz for the turbulently broadened frequency spectrum, to calculate the nonlinear particle flux.
		In the lower-temperature end of this regime, trapped electrons are collisional and all components of the quasilinear particle flux are outward (i.e., in the direction of the gradients).
		Nonlinear effects can alter the phase between the nonadiabatic trapped electron phase-space density and the electrostatic potential, producing inward components in the particle flux.
	library.wolfram.com /infocenter/Articles/2456 (227 words)

	Outline for Lecture #5
		Overall reaction usually has large, negative standard delta G because in overall reaction transport of X (uphill, against the gradient) is coupled to a very downhill reaction, as shown in II.
		Y runs down its gradient, and the energy obtained is used to drive X up its gradient.
		Most (but not all) individual "pump" proteins work only one way in cells, because the standard delta G for the "usual" direction is very negative.
	www.columbia.edu /cu/biology/courses/c2006/lectures/lect5.04.html (2224 words)

	Energy Conservation in Acetogenic Bacteria -- Müller 69 (11): 6345 -- Applied and Environmental Microbiology (Site not responding. Last check: 2007-11-04)
		Acetogenesis and ATP synthesis in Acetobacterium woodii are coupled via a transmembrane primary sodium ion gradient.
		ATP synthases: probing the liganding groups for Na and Li in the c subunit of the ATP synthase from Propionigenium modestum.
		The sodium ion cycle in acetogenic and methanogenic bacteria: generation and utilization of a primary electrochemical sodium ion gradient, p.
	aem.asm.org /cgi/content/full/69/11/6345 (4558 words)

	Energization of Plant Cell Membranes by H+-Pumping ATPases: Regulation and Biosynthesis -- Sze et al. 11 (4): 677 -- ... (Site not responding. Last check: 2007-11-04)
		The circulation of ions across biological membranes is a fundamental
		Barkla, B.J., and Pantoja, O. (1996) Physiology of ion transport across the tonoplast of higher plants.
		Palmgren, M.G. (1998) Proton gradients and plant growth: Role of the plasma membrane H
	www.plantcell.org /cgi/content/full/11/4/677 (6260 words)

	IonPac AS11 Anion-Exchange Column (Site not responding. Last check: 2007-11-04)
		AS11 was specifically designed for fast, gradient screening of inorganic anions and organic acid anions in simple sample matrices.
		ULTRA II, is used for electrolytically regenerated suppression of ion chromatography applications requiring high capacity, fast start-up, and sensitivity.
		The ICS-2000 is the world's first integrated Reagent-Free™ ion chromatograph for isocratic and gradient ion analysis.
	www1.dionex.com /en-us/columns_accessories/ion_exchange/cons3608.html (599 words)

	From the Cover: Sodium ion cycling mediates energy coupling between complex I and ATP synthase -- Gemperli et al. 100 ... (Site not responding. Last check: 2007-11-04)
		From the Cover: Sodium ion cycling mediates energy coupling between complex I and ATP synthase -- Gemperli et al.
		During NADH oxidation, two sodium ions are transported from the cytoplasmic (N-) side to the periplasmic (P-) side of the membrane (11).
		of the positively charged Na ions is compensated by the efflux of protons by the protonophore.
	www.pnas.org /cgi/content/full/100/3/839 (4043 words)

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