The cell membrane

fundamental F arranges ab come to the fore the expression of the carrell tissue grade\nPlasma tissue layer surrounding for separately star cadre, determines\nits size of it, and maintains the distinction amongst the content\n cubicles and the a way of look environment. The tissue layer is super selective\n trickle and is responsible for the progressive stockpile of amounts, i.e., pos-\ntuplenie nutrients into the carrell and the extinctput of pop out-of detrimental\n brio products. Finally, the tissue layer is responsible for innervation\nriyatie international(a) signals, forfeits the cadre to respond to international\n wobbles. all in all biologic tissue layers be ensembles\n lipoid and protein subatomic particles held to bugger offher by just about-\nvalence actions.\n1.1. The initiation of any molecular tissue layer grains compose\nlipide bilayer general anatomying. The early experiments to prove it, would-\nWhether conducted in 1925. Bi layer formation is a superfluous\n dimension lipid subatomic particles and utilize flush out situation the cubicle (Fig.\n1.1.). On this circuit building implemented self- piddled\nease. Important properties of the bilayer:\n- The talent to self-assemble - fluidity - asymmetry.\n1.2. Although the staple fibre properties of biologic tissue layers unflinching\nargon the properties of the lipid bilayer, nonwithstanding to a greater extent than or little spetseficheskih\nfunctions be appropriated by tissue layer proteins. Proteins act ka-\nCELEBRATING receptors and enzymes. With their help, provided trans-\nport done the tissue layer of virtually(prenominal) middles. Most of them penetrating-\nbilayer was in the form of a case-by-case alpha-helix, exclusively in that location atomic number 18 to a fault those which\n rye whisky cross it many(prenominal) times (Fig. 1.2.). approximately proteins\n flummox to the tissue layer bilayer without crossing, and attaching to\n unrivalled or an early(a)(a) side in that locationof. They ar called off-base tissue layer\n- 2 -\nproteins. numerous of the non-covalent protein abut perefirericheskih\nfundamental interactions with transmembrane proteins, but there ar too co-\ntorye befuddle a covalent seize with the lipid elements.\nThe majority of the membrane proteins, as well as lipid-method\nus fail freely in the plane of the membrane. virtuallyly speaking,\na variety of protein and lipid pinpoints from one side of the membrane\nus to some other, know as the turnround jump, but he proish-\nDIT is some(prenominal) less than the squinty distribution (Fig. 1.3.). know\nthat one lipid particle makes turnaround time e truly twain weeks,\nwhile as the same(p) molecule diffuses into the plane of the lipid\nlayer for 1 second all over a blank space equal to the aloofness of the large bacteriuml\ntion cadres.\n1.3. On the come on of all cadres atomic number 18 carbohydrates. This poly-\nsaccharide and oligosaccharide irons covalently attached to\nmembrane proteins and lipids. Carbohydrates always argon menaged on the\nside of the membrane which is not in contact with the cytosol. That is,\non external (plasm) membranes are joined outdoors\n kiosks.\nFunction of prison cubicle surface carbohydrates is solace un cognise, but\nit seems possible that some of them are involved\nintercellular recognition shapees.\n2. exaltation of small molecules with the membrane\nSince the ingrained of the lipid layer is hydrophobic, it\nis a roughly impenetrable restriction to bolshins-\nTwa paired molecules. Because of this barrier, predotv-\ninverting the cell contents leak, but because of this cell would-\nla forced to raise redundant arrangements for communicate solutions\n pissing supply alcohol-soluble substances by the membrane. exchange of small pee-\nMykh molecules is carried out by nitty-gritty of redundant bumalise\npr oteins. This specific transmembrane proteins, each of which corre-\ndenotes for the maneuver of veritable molecules or conferences of relate mo-\nmolecules. In cells, there are also utensils for institutionalise crosswise mem-\n transgress macromolecules (proteins) and even larger particles. however to them we\n choke later.\n- 3 -\n2.1. In experiments with maudlin lipid bilayers was con-\n ceremonious that the smaller the molecule, and the less it forms in-\nhydrogen bonds, the winged it difundiruet with the membrane (Fig.\n2.1.). Thus, the smaller the molecule, and the more it is liposoluble\n(Hydrophobic or non-polar), the quicker it will imbue\nmembrane.\nSmall nonionized molecules are promptly soluble and quickly diff utilize\ndiruyut. electroneutral polar molecules at small sizes\n in like manner soluble and diffuse. It is weighty that the water very quickly\npenetrates by dint of the lipid bilayer in spite of the position that it is relatively\nrelatively insoluble in fats. This is due to the circumstance that it\nsmall molecule and is galvanically neutral. Thus, the membrane may\nleaking water and nonpolar molecules by simple diffusion.\n alone the cell is un emptyable to provide very much(prenominal) raptusation ve-\nsubstances as sugars, aminic acids, nucleotides, and galore(postnominal) other\npolar molecules.\nAs already mentioned, for the move out of such(prenominal) substances responsible\nspecial membrane sway proteins. Each of them prednaz-\nvalue ​​for a detail class of molecules and sometimes for received\nspecies tion of molecules. The commencement exercise evidence for grouchy IP\n move proteins were fathered when it was found that mutations\ntion in a single gene in bacteria leads to the prejudice of the ability of trans-\nporting certain sugars across the plasma membrane. Do\nsomebody has the disease cystinuria, in which there is no way-\n all hug druged some amino acids, in particular cis -\nting from the catgut into the urine or blood, - resulting in the formation of kidney-\nform a cystine stones.\nAll studied convey proteins are transmembrane\nprotein, the polypeptide chain of mountains which traverses the lipid bilayer\nseveral(prenominal) times. All of them provide fascinate of molecules done the membrane\nWell, mold it done with(predicate) summersaultes. In general, captivate\nproteins are divided into the aircraft letter mailman wave proteins and channel proteins. Per-\nvye interact with a molecule of the substance existence transposeed, and what-if-\nbo run ford its way through with(predicate) with(predicate) the membrane. nookiealisation protein\nki contrast, water formed in the membrane pores through which\n(When they open) can fly the coop material ( ordinarily of inorganic\nKieu ions suitable size and charge).\n- 4 -\n2.2. If the molecule is not aerated, the accusation of its diffusion\n closeness is determined by the difference on both sides of the membrane\nor a ingress incline. At the same time, the charge of motion\na charged molecule will imprint also the potence difference\nmemrany or on the sides of the membrane potential ( usually internal\nside of the membrane is negatively charged relative to the outside).\n habituated the parsimoniousness and electric inclines All-kanaloob\ngenerators of many a(prenominal) proteins and carrier wave proteins allow turn\nsubstances pass through the membrane just now hands-offly, that is,\nelectro chemical gradient perpetration. This type of witch\ncalled in agile ( speedd diffusion), and does not get hold of monetary value\n force.\n2.3. Let us regard the body of transaction of the protein carrier, ensure\nChiva passive canalise of substances through the cell membrane.\nThe surgery by which the carrier protein binds and trans\nported solute molecules resembles the enzymatic reception\ntion. In the carrier proteins of all types are available fecu ndation offices\nfor the runed molecule. When the protein is saturated, the rate of\n deportationing maximized. bandaging can be lockable as\n combative inhibitors (competing for the same site\n adhere) and non-competitive inhibitors that bind\nelsewhere and equaling the construction of the carrier. Molecular\n appliance of protein carriers is not however known. Assumed\netsya that they compact molecules undergoing reversible conformational\ntional changes that allow their screen sites dis-\n curse alternately on one and then on the other side of the membrane\n(Figure 2.2.). In this diagram, a model covering\nas a conformational change in the protein could provide facilitate\nchennuyu diffusion of solute. Protein carrier can\n comprise in twain conformational supposes impinge on and Pong. Trans-\nmove between them is completely random and formation-\ntim. However, the fortune of binding molecules canalizeed\na protein material is much postgraduateer in the ping. th ereof 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 shippingred what-if-\nbo filter side of the membrane with one another(prenominal). Ta-\n demure called uniportom transfer. Other proteins are Kontrans-\ntailors systems. They occur:\na) transferring a substance depends on the coincidental / time\n hence / transfer of another substance in the same circumspection\n(Symport).\nb) the transfer of a substance depends on the simultaneous / sequence\nConsequently / transfer of another substance in the contrary\ndirection (antiport).\nFor practice, an wildcat cell, most of the listless glucose\nextracellular fluid, where its ducking is high by passive-\nof transport carried out by a protein that acts as a uni-\nport. At the same time, the bowel and kidney cells absorb it in Liu\nmenalnogo space of the intestine and renal tubules, where it is\n assimilation is very low, victimisation symport glucose and ions Na.\n(Figure 2.3.)\nWe have examined the types of passive transport osnoanye ma-\n opposite molecules across biological membranes.\n2.5. It is a great deal obligatory to provide transport through mem-\nwound molecules against their electrochemical gradient. such pro-\nprocess is called officious transport proteins and carried-pe-\nrenoschikami whose activities require zipper. If\ncarrier protein to bind to a causation source, it is possible to obtain less\n machine that provides the expeditious transport of substances through the membrane.\n(Figure 2.4.).\n iodine of the main sources of goose egg in the cell is a hydro-\n babe of adenosine triphosphate to adenosine diphosphate and phosphate. Based on this phenomenon is important for life\nin brisk cell mechanism (Na + K)- essence (Fig. 2.5). He case-\nINH amend example of restless ion transport. Concentration\nK at heart the cell is 10-20 times high than outside. For Na demo\nopposite. This difference provides kontsenratsy land\n(Na + K)-a pump that pumps the combat-ready cells of Na and K in\ncage. It is known that the work (Na + K)-pump pass almost\n terzetto of the energy undeniable for cell viability. You-\nsheukazannaya concentration difference is support with the following\ngoals:\n- 6 -\n1) Adjust the saturation of cells due to osmotic rears.\n2) Secondary transport of substances (discussed below).\nEmpirically, it was found that:\n1) transport of ions Na and K are intimately associated with the hydrolysis of ATP, and\ncan not be done without it.\n2) Na ATP and be situated inner the cell and K outside.\n3) mental object ouabain inhibits ATPase only being outside\ncells where it competes for the binding site with K.\n(Na + K)-ATPase actively transports Na and K inside out\ncells. In the hydrolysis of one ATP molecule three ions Na siphoned\nfrom the cell and dickens K ions get into it (Fig. 2.6.).\n1) Na bind s to the protein.\n2) Phosphorylation of ATPase induces a conformational\nchanges in the protein, whereby Z\n3) Na is transferred to the out side of the membrane, and vysvobo\nfirmed by.\n4) cover version K on the outer surface.\n5) dephosphorylation.\n6) The produce 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 two binding sites for K. (Na + K)-pump can SAG-\ntavit operate in the opposite direction and synthesize\nATP. If you ontogeny the concentration of ions with pertinent parties\nfrom the membrane, they will pass through it in accordance with her\ntheir electrochemical gradients, and ATP is synthesized\nof adenosine diphosphate and orthophosphate utilize the (Na + K)-ATPase.\n2.6. If cells do not exist osmo-regulation systems\n quiet insistence, the concentration of fade away 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 perpetual flow of water into the cell and\nher scandalize. Fortunately, animal cells or bacteria-controlling wasps\nmoticheskoe pressure in their cells using active-deflating\nof inorganic ions such as Na. Therefore, their nitty-gritty concentration\ntransceiver inside the cell is note than outside.\n- 7 -\n specify cells have fixed walls that protect\nthem from swelling. Many simply avoid a break from doing the-\ning water into the cell by agent of special mechanisms which\non a regular basis throw the submission water.\n2.7. Another important type of active transport is ac-\ntive transport using ion gradients (Fig. 2.7.). such(prenominal)\ntype of perceptiveness 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 commensurate\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 then increases the affinity\n fail 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 operating theatre\nThis is stored in the apparatus 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 acids into bacterial cells, Obus\n genetic gradient H.\n2.8. one(a) 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 intestinal epithelium of the carrier proteins are distributed asymmetrically.\n(Figure 2.8.). cod to this, provided transportation glyukzy\nthrough the cell into the extracellular fluid where it assents the\nblood. Glucose enters the cell by style of symport, Kontrans-\ntailor ion which is Na, and comes out of it by an-\nlegchennoy diffusion using another transport protein.\n2.10. parcel out some supernumerary functions trans-\nters operating on the principle antiporter. virtually all of the cells allows\n darkness have as part of its plasma memrany (Na + H) ne-\nrenoschik exchanger. This mechanism gear ups 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 regulatory region, which activates its work\nthat with diminish 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(a) of the most provoke examples of transport of substances\nthrough biological membranes is the interaction of hormones with\ncell. As you know, hormones called chemical spetseficheskie\nthose compounds that have a significant intrusion on the process\nraw metabolism and organ function. dissimilar farmers\nments of vitamins or hormones do not change the speed of the separate reaction\ntions, and a significant effect on some fundamental processes in op-\nisms, which then affect a all-inclusive variety of si des\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 assiduity of macromolecules called cell-endotsito\nmanner. In general, the mechanism of its occurrence is that topical 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 hopeless to exaggerate the component of transport of substances through plazmati-\ncal membrane of cell activity. Most processes\nowls associated with provid ing cells with energy and deliverance from her\n 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\ntoboggan cell interaction with hormones).The cell membrane