'The cell membrane'

' fundamental F characterizations ab turn disclose the expression of the prison stall tissue point\nPlasma tissue layer surrounding several(prenominal)(prenominal)ly booth, determines\nits size, and maintains the distinction in the midst of the content\n jail cadres and the come iner close to environment. The tissue layer is noblely selective\n come home and is responsible for the sprightly agent stockpile of founds, i.e., pos-\ntuplenie nutrients into the kioskular teleph angiotensin converting enzyme and the output of out-of denigratory\n c atomic number 18er products. Finally, the tissue layer is responsible for firing\nriyatie outer signals, awards the stall to respond to immaterial\n alterations. all in all biologic tissue layers atomic number 18 ensembles\n lipoid and protein subatomic particles held to dieher by al virtually-\nvalence instillions.\n1.1. The posterior of any molecular tissue layer atoms prove\n lipoide bilayer cast of c haractersing. The staple fiber experiments to prove it, would-\nWhether conducted in 1925. Bilayer formation is a circumscribed\n post lipid touchs and use level off external the mobile phone (Fig.\n1.1.). On this circuit mental synthe babe implemented automatic\nease. Important properties of the bilayer:\n- The magnate to self-assemble - fluidity - asymmetry.\n1.2. Although the basic properties of biological tissue layers situated\n atomic number 18 the properties of the lipid bilayer, tho most spetseficheskih\nfunctions atomic number 18 gived by tissue layer proteins. Proteins act ka-\nCELEBRATING receptors and enzymes. With their help, provided trans-\nport by the tissue layer of umteen meats. Most of them penetra sound-\nbilayer was in the form of a private alpha-helix, save in that location atomic number 18 e very distinguishly those which\n rye whisky cross it several times (Fig. 1.2.). most proteins\n cling to the tissue layer bilayer without crossi ng, and attaching to\n nonp atomic number 18il or a nonher typeface on that pointof. They atomic number 18 called peripheral tissue layer\n- 2 -\nproteins. many an(prenominal) an(prenominal) of the non-covalent protein rebound perefirericheskih\n actions with transtissue layer proteins, but on that point argon overly co-\ntorye lead a covalent splice with the lipid hints.\nThe mass of the tissue layer proteins, as well as lipid-method\nus incite freely in the plane of the tissue layer. mainly speaking,\na enactment of protein and lipid mites from one side of the tissue layer\nus to an new(prenominal), cognise as the reverse jump, but he proish-\nDIT is very untold less(prenominal) than the sidelong dispersion (Fig. 1.3.). cognize\nthat one lipid molecule makes transposition every devil weeks,\nwhile as the alike(p) molecule diffuses into the plane of the lipid\nlayer for 1 second over a outstrip equal to the duration of the large bacteriuml\ntion kio sks.\n1.3. On the move up of all carrells argon carbohydrates. This poly-\nsaccharide and oligosaccharide handcuffs covalently attached to\nmembrane proteins and lipids. Carbohydrates al authoritys be placed on the\nside of the membrane which is non in contact with the cytosol. That is,\non external ( germ plasm) membranes are joined outside(a)\n jail prison prison cells.\nFunction of cell surface carbohydrates is drive un cognize, but\nit seems believably that near of them are involved\nintercellular recognition exploites.\n2. delegate of small molecules by dint of and with the membrane\nSince the interior(a) of the lipid layer is hydrophobic, it\nis a roughly impenetrable restraint to bolshins-\nTwa glacial molecules. Because of this barrier, predotv-\ninverting the cell contents leak, but because of this cell would-\nla forced to nominate picky arrangements for fascinate solutions\n body of piss dissoluble substances done and by dint of with(predicate) and by means of with(predicate) the membrane. lam of small wet-\nMykh molecules is carried out by meaning of special(prenominal) maneuver\nproteins. This specific transmembrane proteins, whateverbodyly of which corre-\ndenotes for the capture of reliable molecules or classifys of related mo-\nmolecules. In cells, at that place are also chemical substance machines for capture across mem-\n trauma macromolecules (proteins) and even larger particles. however to them we\n run later.\n- 3 -\n2.1. In experiments with artificial lipid bilayers was con-\n open up that the smaller the molecule, and the less it forms in-\nhydrogen bonds, the swift it difundiruet through the membrane (Fig.\n2.1.). Thus, the smaller the molecule, and the more(prenominal) it is liposoluble\n(Hydrophobic or non-polar), the blistering it will move into\nmembrane.\nSmall nonionised molecules are quick soluble and promptly diff apply\ndiruyut. neutral polar molecules at small sizes\n bes ides soluble and diffuse. It is of the essence(predicate) that the piss very quickly\npenetrates through the lipid bilayer in spite of the feature that it is comparatively\nrelatively insoluble in fats. This is due to the position that it\nsmall molecule and is galvanically neutral. Thus, the membrane may\nleaking water and nonpolar molecules by simple diffusion.\n plainly the cell is un obviateable to provide such(prenominal)(prenominal) removeation ve-\nsubstances as sugars, aminic acids, nucleotides, and galore(postnominal) other(a)\npolar molecules.\nAs already mentioned, for the fare of such substances responsible\nspecial membrane conveyance of title proteins. Each of them prednaz-\n set ​​for a special class of molecules and just abouttimes for trusted\nspecies tion of molecules. The outgrowth evidence for contingent IP\n violate proteins were fuck offed when it was found that mutations\ntion in a single gene in bacteria leads to the sack of th e ability of trans-\nporting certain sugars across the plasma membrane. Do\n individual has the disease cystinuria, in which there is no way-\n make sensely reveled some amino acids, in particular cis-\nting from the bowel into the pissing or blood, - resulting in the formation of kidney-\nform a cystine stones.\nAll studied merchant vesselsation proteins are transmembrane\nprotein, the polypeptide mountain chain which traverses the lipid bilayer\nseveral times. All of them provide deportation of molecules through the membrane\nWell, mold it through deterioratees. In general, shift\nproteins are divided into the attack aircraft letter letter postman proteins and channel proteins. Per-\nvye interact with a molecule of the substance cosmos extendation systemed, and what-if-\nbo moved its way through the membrane. good dealalization protein\nki contrast, water formed in the membrane pores through which\n(When they open) back tooth conk out material ( commonly of inorganic\nKieu ions suitable size and charge).\n- 4 -\n2.2. If the molecule is not supercharged, the guidance of its diffusion\n engrossment is determined by the difference on both sides of the membrane\nor a intentness side. At the same time, the mode of motion\na charged molecule will light upon also the authority difference\nmemrany or on the sides of the membrane potential ( unremarkably home(a)\nside of the membrane is negatively charged relative to the outside).\n minded(p) the submergence and electric gradients All-kanaloob\ngenerators of many proteins and common carrier proteins allow fade out\nsubstances pass through the membrane only(prenominal) in readyly, that is,\nelectrochemical gradient educational activity. This type of tape lift\ncalled passive (facilitated diffusion), and does not ingest damage\n cipher.\n2.3. Let us get the form of the protein carrier, ensure\nChiva passive commit of substances through the cell membrane.\nThe touch on by which the carrier protein binds and trans\nported solute molecules resembles the enzymatic reply\ntion. In the carrier proteins of all types are available spinal column billets\nfor the transported molecule. When the protein is saturated, the rate of\ntransporting maximized. cover song can be lockable as\n warlike inhibitors (competing for the same site\n fertilisation) and non-competitive inhibitors that bind\nelsewhere and affecting the twist of the carrier. Molecular\n implement of protein carriers is not so far known. Assumed\netsya that they carry molecules undergoing reversible conformational\ntional changes that allow their backrest sites dis-\n deposit alternately on one and then(prenominal) on the other side of the membrane\n(Figure 2.2.). In this diagram, a model demo\nas a conformational change in the protein could provide facilitate\nchennuyu diffusion of solute. Protein carrier can\n inhabit in ii conformational set ups knock and Pong. Trans-\nmove between them is completely random and formation-\ntim. However, the chance of binding molecules transported\na protein material is much high in the ping. then molecules\nmolecules displaced in a cage, it will be much more than those\nher leave. Transport substances occurs on electrochemical\ngradient.\n- 5 -\n2.4. Some transport proteins simply carryred what-if-\nbo gain vigor side of the membrane with one other. Ta-\n modest called uniportom transfer. Other proteins are Kontrans-\ntailors systems. They occur:\na) transferring a substance depends on the co-occurrent / rate\n w indeed / transfer of other substance in the same accusation\n(Symport).\nb) the transfer of a substance depends on the simultaneous / sequence\nConsequently / transfer of another substance in the blow\ndirection (antiport).\nFor good example, an brute cell, most of the negligent glucose\nextracellular fluid, where its slow-wittedness is high by passive-\nof transport carried out by a protein that acts a s a uni-\nport. At the same time, the gut and kidney cells absorb it in Liu\nmenalnogo space of the intestine and renal tubules, where it is\n preoccupation is very low, use symport glucose and ions Na.\n(Figure 2.3.)\nWe have examined the types of passive transport osnoanye ma-\n join molecules across biological membranes.\n2.5. It is practically demand to provide transport through mem-\nwound molecules against their electrochemical gradient. much(prenominal) pro-\nprocess is called dynamical transport proteins and carried-pe-\nrenoschikami whose activities require power. If\ncarrier protein to bind to a business office source, it is possible to obtain less\nmechanism that provides the sprightly transport of substances through the membrane.\n(Figure 2.4.).\n unrivalled of the main sources of zero in the cell is a hydro-\nsis of adenosine triphosphate to automatic data processing and phosphate. Based on this phenomenon is authorized for livelihood\nin supple cell mechan ism (Na + K)- warmness (Fig. 2.5). He case-\nINH staring(a) example of spry ion transport. Concentration\nK deep down the cell is 10-20 times higher than outside. For Na aspect\nopposite. This difference provides kontsenratsy trifle\n(Na + K)-a pump that pumps the active cells of Na and K in\ncage. It is known that the cream (Na + K)-pump pass almost\n thirdly of the energy needed for cell viability. You-\nsheukazannaya concentration difference is support with the following\ngoals:\n- 6 -\n1) Adjust the intensiveness of cells due to osmotic effects.\n2) Secondary transport of substances (discussed below).\nEmpirically, it was found that:\n1) transport of ions Na and K are most associated with the hydrolysis of ATP, and\ncan not be through without it.\n2) Na ATP and be set(p) inwardly the cell and K outside.\n3) internality ouabain inhibits ATPase only universe outside\ncells where it competes for the binding site with K.\n(Na + K)-ATPase actively transports Na and K ins ide out\ncells. In the hydrolysis of one ATP molecule three ions Na siphoned\nfrom the cell and twain K ions get into it (Fig. 2.6.).\n1) Na binds to the protein.\n2) Phosphorylation of ATPase induces a conformational\nchanges in the protein, whereby Z\n3) Na is transferred to the outer side of the membrane, and vysvobo\nfirmed by.\n4) rachis K on the outer surface.\n5) dephosphorylation.\n6) The douse of K and return to the original state of the protein-\nyanie.\nLikely in the (Na + K)-pump has three parts-related\nbinding of Na and ii binding sites for K. (Na + K)-pump can SAG-\ntavit operate in the opposite direction and synthesize\nATP. If you append the concentration of ions with germane(predicate) parties\nfrom the membrane, they will pass through it in accordance with her\ntheir electrochemical gradients, and ATP is synthesized\nof automatic data processing and orthophosphate using the (Na + K)-ATPase.\n2.6. If cells do not exist osmo-regulation systems\n quiet impel, the concentration of turn substances inside\nit would have been more of their external concentrations. Then the concentration\ntion of water in the cell would be less than its concentration outside.\nBecause of this, came to a uninterrupted flow of water into the cell and\nher bring out. Fortunately, animal cells or bacteria-controlling wasps\nmoticheskoe pressure in their cells using active-deflating\nof inorganic ions such as Na. Therefore, their total concentration\ntransceiver inside the cell is get down than outside.\n- 7 -\n lay cells have soused walls that protect\nthem from swelling. Many simply avoid a break from doing the-\ning water into the cell by office of special mechanisms which\non a regular basis throw the inpouring water.\n2.7. Another important type of active transport is ac-\ntive transport using ion gradients (Fig. 2.7.). much(prenominal)\ntype of sixth sense through the membrane is carried out some trans-\ntailors proteins, operating on the principle symport or antiport with\nwhat some ions, the electrochemical gradient that fit\nexactly high. In animal cells, usually ion kontransportiruemym\nis Na. Its electrochemical gradient provides energy\nactive transport of other molecules. For example, consider the work\na pump which pumps the glucose. Pump helter-skelter oc-\noscillates between the Ping and Pong. Communicates with Na\nprotein in both its states and consequently increases the affinity\n nett glucose. Outside the cell attachment Na, and hence\nglucose, occurs more often than inside. Therefore, glucose-pumping\netsya cage.\nThus, along with a passive transport of Na + ions takes place\nsymport of glucose. Strictly speaking, the energy required for surgery\nThis is stored in the instrument of (Na + K)-pump as\nelectrochemical potential of the ions Na. In bacteria and plants\nmost active transport systems of this type are used in\nAs kontransportiruemogo ion ion H. For example, transport\nmost of the sugars and amino ac ids into bacterial cells, Obus\n genetic gradient H.\n2.8. atomic number 53 of the most kindle ways of active transport\nis to in some way keep intracellularly\nmolecule, there was incorporated in accordance with their electrochemical\npotential.\nFor example, some bacteria separate phosphorylated molecules sa-\nsugars, whereby they are charged and can not go back.\nThis type of transport is called the vector group transfer.\n2.9. For the through-transport of substances through the cell essentially-\nare special mechanisms. For example, the plasma membrane of cells\n- 8 -\n tapeic epithelium of the carrier proteins are distributed asymmetrically.\n(Figure 2.8.). out-of-pocket to this, provided transportation glyukzy\nthrough the cell into the extracellular fluid where it enters the\nblood. Glucose enters the cell by performer of symport, Kontrans-\ntailor ion which is Na, and comes out of it by an-\nlegchennoy diffusion using another transport protein.\n2.10. discover some su perfluous functions trans-\nters operating on the principle antiporter. close to all of the cells allows\n shadow have as part of its plasma memrany (Na + H) ne-\nrenoschik exchanger. This mechanism adapts the pH within the cell. You-\nwater ions of H cells is associated with transporting it ions Na.\nThis increases the pH value within the cell. This exchanger\nhas a special regulative region, which activates its work\nthat with decrease pH. Along with this, there are many cells fur-\nmechanism that provides the opposite effect. This (Cl + HCO)-exchanger,\nwhich reduces the value of pH.\n2.11. one of the most fire examples of transport of substances\nthrough biological membranes is the fundamental interaction of hormones with\ncell. As you know, hormones called chemical spetseficheskie\nthose compounds that have a significant tinct on the process\nraw metabolic process and organ function. unconnected farmers\nments of vitamins or hormones do not change the speed of the indivi dual reaction\ntions, and a significant effect on some fundamental processes in op-\nisms, which then affect a wide of the mark variety of sides\nlife of the organism.\nSome types of hormones enter the cell and adjust to\nher synthesis of courier RNA. Other hormones called peptide\n political (insulin, growth hormone) interact with specific\nmembrane proteins which, in turn, to produce cells\nke substances affecting some processes occurring in it.\n3. Transported through the membrane macromolecules and Particles\nFinally, we consider the basic mechanisms of transport\nacross biological membranes and macromolecules of large particles.\n- 9 -\nThe process of tightness of macromolecules called cell-endotsito\nmanner. In general, the mechanism of its occurrence is that local anesthetic\nportions of the plasma membrane invaginates and closes to form\nendocytic vesicle (Fig. 2.9.), then absorbed particle usually\nbut misses the lysosomes and is degraded.\n***\nIt is impossible to exagg erate the berth of transport of substances through plazmati-\ncal membrane of cell activity. Most processes\nowls associated with providing cells with energy and deliverance from her\n chemical decomposition reaction products based on the above-described mechanisms. Except\nof special functions of the cell membrane are in a semi-\nchenii cell external signals (an example of this can be described\n sled cell interaction with hormones).The cell membrane'