Cell membrane - cov txheej txheem ntawm cov cell, tiv thaiv nws los ntawm ib puag ncig sab nraud. Nrog kev pab los ntawm nws, nws cuam tshuam nrog qhov chaw intercellular thiab yog ib feem ntawm cov kab mob lom. Nws daim nyias nyias muaj cov qauv tshwj xeeb uas muaj cov lipid bilayer, ib qho thiab ib nrab ntawm cov protein. Cov tom kawg yog cov molecules loj uas ua haujlwm ntau yam. Feem ntau, lawv tau koom nrog hauv kev thauj cov khoom tshwj xeeb, qhov concentration ntawm qhov sib txawv ntawm daim nyias nyias yog ua tib zoo tswj.
Txoj kev npaj ntawm cell membrane qauv
Lub plasma membrane yog ib qho kev sib sau ntawm cov roj molecules thiab cov proteins nyuaj. Nws cov phospholipids, nrog rau lawv cov hydrophilic residues, yog nyob rau sab nraud ntawm daim nyias nyias, tsim cov lipid bilayer. Tab sis lawv cov cheeb tsam hydrophobic, muaj cov fatty acid residues, yog tig mus rau sab hauv. Qhov no tso cai rau koj los tsim cov kua dej-kua siv lead ua uas tuaj yeem hloov pauv cov duab tas li thiab nyob rau hauv qhov sib npaug sib npaug.
Cov qauv ntawm cov qauv no tso cai rau koj txwv lub xovtooj ntawm qhov chaw intercellular, vim tias daim nyias nyias yog impermeable rau dej thiab tag nrho cov tshuaj yaj hauv nws. Ib co complex integral proteins, semi-integral thiab nto molecules yog immersed nyob rau hauv lub thickness ntawm daim nyias nyias. Los ntawm lawv, lub cell cuam tshuam nrog lub ntiaj teb sab nraud, tswj hwm homeostasis thiab tsim cov ntaub so ntswg lom neeg.
YPlasma membrane proteins
Txhua cov protein molecules uas nyob rau ntawm qhov chaw lossis hauv cov tuab ntawm cov plasma membrane tau muab faib ua hom nyob ntawm qhov tob ntawm lawv qhov tshwm sim. Muaj cov proteins uas nkag mus rau hauv lipid bilayer, ib nrab ntawm cov proteins uas tshwm sim hauv thaj av hydrophilic ntawm daim nyias nyias thiab tawm mus rau sab nraud, nrog rau cov proteins uas nyob rau sab nraud ntawm daim nyias nyias. Integral protein molecules permeate plasmalemma nyob rau hauv ib txoj kev tshwj xeeb thiab tuaj yeem txuas nrog lub receptor apparatus. Ntau ntawm cov molecules permeate tag nrho cov membrane thiab hu ua transmembrane. Tus so yog anched nyob rau hauv hydrophobic feem ntawm daim nyias nyias thiab tawm mus rau sab hauv lossis sab nrauv.
Feem ntau, ion channels ua raws li cov proteins uas tsis sib xws. Cov qauv no yog lub luag haujlwm rau kev thauj mus los ntawm qee yam khoom mus rau hauv lossis tawm ntawm lub cell. Lawv muaj ob peb protein subunits thiab ib tug active site. Thaum raug rau ib qho ligand ntawm qhov chaw ua haujlwm, sawv cev los ntawm ib qho tshwj xeebamino acids, muaj kev hloov nyob rau hauv lub conformation ntawm ion channel. Cov txheej txheem zoo li no tso cai rau koj qhib lossis kaw cov channel, yog li pib lossis nres cov khoom thauj khoom nquag.
Qee lub ion channel qhib feem ntau, tab sis thaum lub teeb liab tau txais los ntawm cov protein receptor lossis thaum ib qho ligand txuas, lawv tuaj yeem kaw, nres cov ion tam sim no. Lub hauv paus ntsiab lus ntawm kev ua haujlwm no npau taws mus rau qhov tseeb tias kom txog thaum lub receptor lossis lub teeb liab humoral tau txais kom tsis txhob muaj kev thauj mus los ntawm qee yam khoom, nws yuav ua tiav. Thaum lub teeb liab tau txais, kev thauj khoom yuav tsum nres.
Feem ntau ntawm cov proteins ib txwm ua raws li cov ion channel ua haujlwm los tiv thaiv kev thauj mus los kom txog rau thaum ib qho ligand txuas mus rau qhov chaw nquag. Tom qab ntawd qhov kev thauj mus los ion yuav raug qhib, uas yuav tso cai rau lub membrane kom rov ua dua. Qhov no algorithm ntawm kev khiav hauj lwm ntawm ion channel yog ib yam rau cov hlwb ntawm excitable tib neeg cov ntaub so ntswg.
Nyob ntawm cov proteins embedded
Txhua daim nyias nyias cov proteins (ib qho, ib nrab thiab ib nrab) ua haujlwm tseem ceeb. Nws yog qhov tseeb vim tias lawv lub luag haujlwm tshwj xeeb hauv lub neej ntawm cov cell uas lawv muaj qee yam kev koom ua ke rau hauv phospholipid membrane. Qee cov proteins, feem ntau cov no yog cov ion channel, yuav tsum ua kom tag nrho cov plasmalemma thiaj li paub txog lawv txoj haujlwm. Tom qab ntawd lawv hu ua polytopic, uas yog, transmembrane. Lwm tus neeg nyob hauv thaj chaw los ntawm lawv qhov chaw thauj tog rau nkoj hauv qhov chaw hydrophobic ntawm phospholipid bilayer, thiab qhov chaw nquag txuas mus rau sab hauv lossis tsuas yog mus rau sab nraud.nto ntawm cell membrane. Tom qab ntawd lawv hu ua monotopic. Feem ntau lawv yog cov receptor molecules uas tau txais lub teeb liab los ntawm qhov chaw ntawm daim nyias nyias thiab xa mus rau qhov tshwj xeeb "intermediary".
Txhim kho cov proteins ib txwm
Tag nrho cov molecules tag nrho nkag mus rau thaj tsam hydrophobic thiab raug kho rau hauv nws txoj hauv kev uas lawv txoj kev txav tsuas yog tso cai raws li daim nyias nyias. Txawm li cas los xij, kev nkag mus ntawm cov protein mus rau hauv lub cell, ib yam li kev tshem tawm ntawm cov protein molecule los ntawm cytolemma, yog tsis yooj yim sua. Muaj ib qho kev sib txawv uas cov proteins ntawm cov membrane nkag mus rau cytoplasm. Nws yog txuam nrog pinocytosis los yog phagocytosis, uas yog, thaum lub cell captures ib tug khoom los yog kua thiab ib puag ncig nws nrog ib daim nyias nyias. Tom qab ntawd nws tau rub mus rau hauv nrog rau cov proteins uas nyob hauv nws.
Tau kawg, qhov no tsis yog txoj hauv kev zoo tshaj plaws los pauv lub zog hauv lub xov tooj ntawm tes, vim tias tag nrho cov proteins uas yav dhau los ua haujlwm ua cov receptors lossis ion channel yuav raug zom los ntawm lysosome. Qhov no yuav xav tau lawv cov synthesis tshiab, uas ib feem tseem ceeb ntawm lub zog reserves ntawm macroergs yuav siv. Txawm li cas los xij, thaum lub sij hawm "kev siv" ntawm cov molecules ntawm ion channels los yog receptors feem ntau puas, mus txog rau lub detachment ntawm seem ntawm cov molecule. Qhov no kuj yuav tsum tau lawv resynthesis. Yog li ntawd, phagocytosis, txawm tias nws tshwm sim nrog kev sib cais ntawm nws tus kheej receptor molecules, kuj yog ib txoj hauv kev ntawm lawv qhov kev txuas ntxiv mus tas li.
Hydrophobic kev sib cuam tshuam ntawm ib qho proteins
Raws li nws yogRaws li tau piav saum toj no, ib qho membrane proteins yog complex molecules uas zoo li yuav daig nyob rau hauv lub cytoplasmic membrane. Nyob rau tib lub sijhawm, lawv tuaj yeem ua luam dej dawb hauv nws, txav mus rau plasmalemma, tab sis lawv tsis tuaj yeem tawg tawm ntawm nws thiab nkag mus rau qhov chaw intercellular. Qhov no yog pom tau hais tias vim qhov peculiarities ntawm hydrophobic kev sib cuam tshuam ntawm ib qho proteins nrog membrane phospholipids.
Cov chaw ua haujlwm ntawm cov proteins ib txwm muaj nyob rau sab hauv lossis sab nrauv ntawm lipid bilayer. Thiab qhov tawg ntawm macromolecule, uas yog lub luag haujlwm rau kev txhim kho nruj, yog ib txwm nyob ntawm thaj chaw hydrophobic ntawm phospholipids. Vim muaj kev cuam tshuam nrog lawv, tag nrho cov transmembrane proteins yeej ib txwm nyob rau hauv lub thickness ntawm cell membrane.
Kev ua haujlwm ntawm ib qho macromolecules
Txhua qhov sib xyaw ua ke cov protein muaj qhov chaw thauj tog rau nkoj nyob ntawm cov hydrophobic residues ntawm phospholipids thiab lub chaw ua haujlwm. Qee cov molecules tsuas muaj ib qho chaw ua haujlwm thiab nyob rau sab hauv lossis sab nraud ntawm daim nyias nyias. Tseem muaj cov molecules nrog ntau qhov chaw ua haujlwm. Tag nrho cov no nyob ntawm cov haujlwm ua los ntawm cov khoom siv thiab cov khoom siv peripheral. Lawv thawj txoj haujlwm yog kev thauj mus los.
Protein macromolecules, uas yog lub luag haujlwm rau kev nkag mus ntawm ions, muaj ntau lub subunits thiab tswj cov ion tam sim no. Feem ntau, plasma daim nyias nyias tsis tuaj yeem dhau hydrated ions, vim nws yog lipid los ntawm xwm. Lub xub ntiag ntawm ion channels, uas yog ib feem ntawm cov protein, tso cai rau ions nkag mus rau hauv lub cytoplasm thiab recharge lub cell membrane. Qhov no yog lub ntsiab mechanism rau qhov tshwm sim ntawm daim nyias nyias muaj peev xwm ntawm excitable cov ntaub so ntswg hlwb.
Receptor molecules
Qhov thib ob muaj nuj nqi ntawm ib qho molecules yog receptor muaj nuj nqi. Ib qho lipid bilayer ntawm daim nyias nyias siv kev tiv thaiv kev ua haujlwm thiab txwv tag nrho cov cell los ntawm ib puag ncig sab nraud. Txawm li cas los xij, vim muaj cov receptor molecules, uas sawv cev los ntawm cov proteins ib txwm muaj, lub xov tooj ntawm tes tuaj yeem tau txais cov cim los ntawm ib puag ncig thiab cuam tshuam nrog nws. Ib qho piv txwv yog cardiomyocyte adrenal receptor, cell adhesion protein, insulin receptor. Ib qho piv txwv tshwj xeeb ntawm cov protein receptor yog bacteriorhodopsin, ib qho tshwj xeeb membrane protein pom nyob rau hauv qee cov kab mob uas tso cai rau lawv teb rau lub teeb.
Intercellular interaction proteins
Pab pawg thib peb ntawm kev ua haujlwm ntawm cov proteins ib txwm yog kev siv ntawm kev sib cuag ntawm tes. Ua tsaug rau lawv, ib lub xovtooj tuaj yeem koom nrog lwm tus, yog li tsim cov saw hlau ntawm cov ntaub ntawv xa mus. Nexuses ua haujlwm raws li cov txheej txheem no - qhov sib txawv ntawm kev sib txuas ntawm cardiomyocytes, uas dhau los ntawm lub plawv dhia. Tib lub hauv paus ntsiab lus ntawm kev ua haujlwm yog pom nyob rau hauv synapses, los ntawm qhov uas ib qho impulse kis tau rau hauv cov hlab ntsha.
Los ntawm cov proteins ib txwm, cov hlwb kuj tuaj yeem tsim kev sib txuas ntawm cov neeg kho tshuab, uas yog ib qho tseem ceeb hauv kev tsim cov ntaub so ntswg. Tsis tas li ntawd, cov proteins ib txwm tuaj yeem ua lub luag haujlwm ntawm daim nyias nyias enzymes thiab koom nrog kev hloov pauv ntawm lub zog, suav nrog cov paj hlwb impulses.
