Tshwj xeeb tshaj yog cov qauv thiab cov kev ua ntawm cell week

Nyob rau hauv 1972 nws tau muab tso rau pem hauv ntej qhov kev tshawb xav tias cov cov permeable membrane lwm tus lub cell thiab ua ib tug xov tooj uas tseem ceeb heev kev pab raws qib, thiab cov qauv thiab cov kev ua ntawm cell week tseem ceeb teeb meem hais txog cov hauj lwm ntawm txhua lub hlwb nyob rau hauv lub cev. Cell kev tshawb xav los ua ntau nyob rau hauv lub xyoo pua 17th, nrog rau cov invention ntawm lub tshuab kuaj kab. Nws yog kawm tau hais tias cov nroj tsuag thiab tsiaj ntaub so ntswg yog muaj li ntawm hlwb, tab sis vim yog qhov uas tsis muaj kev daws teeb meem ntawm lub ntaus ntawv nws yog tsis yooj yim sua kom pom tej teeb meem nyob ib ncig ntawm cov tsiaj hlwb. Nyob rau hauv lub xyoo pua 20th, cov tshuaj xwm ntawm daim nyias nyias twb soj ntsuam nyob rau hauv ntau yam, nws pom hais tias nws cov hauv paus yog cov lipids.

Qauv thiab muaj nuj nqi ntawm cell week

Lub cell daim nyias nyias puag ncig lub cytoplasm ntawm nyob hlwb, lub cev nkauj nraug intracellular Cheebtsam ntawm cov sab nraud ib puag ncig. Yog ho nphav kiag, cov kab mob thiab cov nroj tsuag kuj muaj cell phab ntsa uas tiv thaiv thiab tiv thaiv kom txhob cov zaj uas lub loj molecules. Cell week kuj ua si ib lub luag hauj lwm nyob rau hauv lub tsim ntawm lub cytoskeleton thiab yog txuas mus rau lub extracellular matrix lwm tseem ceeb heev hais. Qhov no yog tsim nyog nyob rau hauv thiaj li yuav kom lawv ua ke mus rau daim ntawv so ntswg thiab kabmob. Nta ntawm lub cell daim nyias nyias qauv muaj xws li permeability. Lub ntsiab muaj nuj nqi yog los tiv thaiv. Lub membrane muaj ib tug phospholipid txheej nrog kos proteins. Qhov no yog ib feem yog muab kev koom tes nyob rau hauv dab xws li cell adhesion, ion conductivity thiab taw qhia systems thiab ua hauj lwm pab raws li ib tug mounting nto rau ob peb extracellular lug, nrog rau cov phab ntsa glycocalyx thiab nrog cytoskeleton. Lub membrane kuj khaws lub peev xwm ntawm lub hlwb, ua hauj lwm raws li ib tug xim lim. Nws yog xaiv permeable rau ions thiab organic molecules thiab ntawm lwm yam uas lub zog ntawm tus hais.

Lom mechanisms uas cell daim nyias nyias

1. passive diffusion: ib co tshuaj (me me molecules, ions) xws li carbon dioxide (CO2) thiab cov pa (O2), muaj peev xwm txeem cov ntshav nyias nyias los ntawm diffusion. Lub casing ua raws li ib tug teeb meem rau tej yam molecules thiab ions, lawv yuav tsum tau feeb meej nyob rau ob sab.

2. Cov transmembrane protein raws thiab transporters: cov as-ham xws li zib los yog amino acids, yuav tsum tau mus rau hauv lub tawb, thiab ib co metabolic khoom yuav tsum tau tawm nws.

3. endocytosis - yog tus txheej txheem uas molecules yog absorbed. me ntsis deformation (intussusception) yog tsim nyob rau hauv cov ntshav membrane, nyob rau lub substance yuav tsum tau thauj, yog nqos tau. Qhov no yuav tsum tau zog, thiab yog li, yog ib daim ntawv ntawm active thauj.

4. Exocytosis: tshwm sim nyob rau hauv txawv hlwb kom tshem tawm undigested tshuaj residues coj endocytosis rau paim tshuaj, xws li cov tshuaj hormones, enzymes, thiab thauj khoom tag nrho txoj kev los ntawm tus xovtooj ntawm barrier.

molecular qauv

Cell membrane - ib tug lom plhaub muaj yeej tseem zoo ntawm phospholipid thiab nkauj nraug cov ntsiab lus ntawm tag nrho cov hlwb los ntawm cov ib puag ncig. Tus txheej txheem ntawm kev tsim tshwm sim nthawv nyob rau hauv ib txwm tej yam kev mob. Yuav kom to taub tus txheej txheem no thiab kom piav qhia txog cov qauv thiab cov kev ua ntawm cell week, raws li zoo raws li lub zog tsim nyog rau kev ntsuam xyuas qhov xwm ntawm tus phospholipid qauv, uas yog cov yam ntxwv ntawm cov yam ntxwv polarization. Thaum phospholipids nyob rau hauv lub aqueous puag ncig ntawm lub cytoplasm cuag ib tug tseem ceeb heev concentration, lawv cov chav hauv micelles, uas muaj ntau ruaj khov nyob rau hauv ib tug aqueous ib puag ncig.

membrane zog

• Stability. Qhov no txhais tau tias tom qab lub tsim ntawm lub cev qhuav dej ntawm daim nyias nyias yog tsis zoo li.
• Zog. Lub lipid lub hnab ntawv robust txaus los mus tiv thaiv cov zaj uas lub ncov qaumteb qabteb tshuaj, tsim los ntawm tus ciam teb yuav kis tsis tau raws li solutes (ions, qabzib, amino acids), thiab ib tug loj npaum li cas molecules (cov nqaijrog).
• Lub dynamic xwm. Qhov no yog tej zaum qhov tseem ceeb tshaj plaws vaj tse, yog hais tias peb xav txog cov qauv ntawm cov cell. Lub cell daim nyias nyias tej zaum yuav tsum tau raug mus txawv hom, thiab yuav daim ntau quav tso khoov thiab tsis lov. Nyob rau hauv tej yam tshwj xeeb, xws li cov fusion ntawm cov hlwv budding los yog nws muaj peev xwm yuav tawg, tab sis ib ntus xwb. Thaum chav tsev kub, lub lipid Cheebtsam yog nyob rau hauv qhov, chaotic tsab ntawv tsa suab, txoj kev ua ib tug ruaj khov kua ciam.

Dej mosaic qauv

Hais txog cov qauv thiab cov kev ua ntawm cell week, nws yog ib qho tseem ceeb kom nco ntsoov tias nyob rau hauv hnub no tus kev nthuav qhia ntawm daim nyias nyias raws li cov kua mosaic qauv, nws twb soj ntsuam los ntawm zaum nyob rau hauv 1972 los ntawm Singer thiab Nicholson. Lawv lub hom phiaj qhia peb lub ntsiab nta ntawm cov qauv ntawm cov daim nyias nyias. Integral membrane cov nqaijrog pab mus rau mosaic qauv rau cov daim nyias nyias, thiab lawv muaj peev xwm ntawm sab zog nyob rau hauv lub dav hlau vim lub volatile xwm ntawm lub lipid lub koom haum. Transmembrane cov nqaijrog kuj muaj feem mobile. Ib qho tseem ceeb feature ntawm daim nyias nyias qauv yog nws asymmetry. Yuav ua li cas yog cov qauv ntawm cov cell? Lub cell daim nyias nyias, nucleus, protein thiab thiaj li nyob. Cell yog ib tug siv chav tsev ntawm lub neej, thiab tag nrho cov kab mob muaj xws li ib los yog ntau yam hlwb, txhua tus uas muaj ib yam teeb meem uas cais nws los ntawm qhov ib puag ncig. Qhov no txheej ciam ntawm lub cell tseem hu ua cov ntshav membrane. Nws muaj plaub ntau hom molecules: phospholipids, cholesterol, cov nqaijrog thiab carbohydrates. Dej mosaic qauv qhia txog cov qauv ntawm cov cell daim nyias nyias raws li nram no: saj zawg zog thiab elastic, lub taub hau tsa ib tug zaub roj, thiaj li hais tias tag nrho cov neeg molecules cia li ntab nyob rau hauv ib cov kua nruab nrab, thiab lawv yuav tau tsiv mus nyob laterally hauv no plhaub. Mosaic nruab nrab yog ib yam dab tsi uas muaj ntau ntau qhov chaw. Nyob rau hauv cov ntshav membrane nws yog hais phospholipids, cholesterol molecules, cov nqaijrog thiab carbohydrates.

phospholipids

Phospholipids tshwm sim tawm lub yooj yim qauv ntawm cov cell daim nyias nyias. Cov molecules muaj ob tug sib txawv kawg: ib lub taub hau thiab tus Tsov tus tw. Lub taub hau kawg muaj ib tug phosphate pab pawg neeg thiab yog hydrophilic. Qhov no txhais tau tias nws yog attracted rau dej lwg me me. Tus Tsov tus tw muaj hydrogen thiab cov pa roj carbon atoms, hu ua fatty acid chains. Cov chains yog hydrophobic, lawv tsis nyiam mus sib tov nrog cov dej lwg me me. Qhov no tus txheej txheem yog zoo li dab tsi tshwm sim thaum koj hliv cov roj rau hauv cov dej, qab hau nws tsis yaj nyob rau hauv nws. Nta ntawm lub cell daim nyias nyias qauv muaj feem xyuam rau qhov thiaj li hu ua lipid bilayer, uas muaj phospholipids. Hydrophilic phosphate hau yeej ib txwm positioned nyob qhov twg muaj dej nyob rau hauv daim ntawv ntawm intracellular thiab extracellular kua. Lub hydrophobic tails ntawm phospholipids nyob rau hauv daim nyias nyias yog ib lub koom haum nyob rau hauv xws li ib tug txoj kev uas yuav ua rau lawv tam sim ntawd los ntawm cov dej.

Cholesterol, cov nqaijrog thiab carbohydrates

Hnov lo lus "cholesterol", cov neeg feem ntau yog xav hais tias nws yog phem. Tab sis nyob rau hauv qhov tseeb, cholesterol yog ib qho tseem ceeb feem ntawm cell week. Nws molecule muaj plaub rings ntawm hydrogen thiab cov pa roj carbon atoms. Lawv yog cov hydrophobic thiab muaj nyob ntawm cov hydrophobic tails nyob rau hauv lub lipid lis-txheej. Lawv tseem ceeb yog kom muaj taub hau, lawv txhawb ntxiv rau daim nyias nyias, tiv thaiv kev sib tshuam. cholesterol molecules kuj tuav lub phospholipid tails tuaj mus rau hauv kev sib cuag thiab solidifies. Qhov no saib kuas fluidity thiab yooj. Membrane cov nqaijrog muaj ib tug muaj nuj nqi ntawm enzymes leeb tshuaj tshua, ua raws li receptors rau tej molecules los yog cov tshuaj thauj los ntawm lub cell daim nyias nyias.

Carbohydrates, los yog suab thaj, muaj nyob tsuas yog nyob rau hauv lub extracellular sab ntawm lub cell daim nyias nyias. Ua ke lawv rau glycocalyx. Nws muab cushioning thiab kev tiv thaiv ntawm cov ntshav membrane. Raws li cov lug thiab hom ntawm carbohydrates nyob rau hauv lub cev glycocalyx ntawm hlwb yuav paub txog thiab txiav txim seb lawv yuav tsum tau muaj los yog tsis.

membrane cov nqaijrog

Tus qauv ntawm lub cell daim nyias nyias ntawm ib tug tsiaj cell yog inconceivable tsis muaj xws li ib tug tseem ceeb feem ntawm cov protein. Dua li no, lawv yog considerably ua tsis tau zoo rau qhov loj ntawm lub lwm yam tseem ceeb tivthaiv - lipids. Muaj peb theem pib hom ntawm daim nyias nyias proteins.

• Integral. Lawv kiag li npog lub lis-txheej, qhov cytoplasm thiab cov extracellular nruab nrab. Lawv nqa tawm ib tug thauj thiab taw muaj nuj nqi.
• Peripheral. Cov nqaijrog uas txuas mus rau cov daim nyias nyias los ntawm kev siv electrostatic, los yog hydrogen bonds nyob rau hauv lawv cov cytoplasmic los yog extracellular chaw. Lawv koom yeej tseem zoo raws li ib tug fastening txhais tau rau ib proteins.
• Transmembrane. Lawv khiav lag luam enzymatic thiab taw zog, thiab modulate qhov yooj yim qauv ntawm cov lipid lis-txheej membrane.

Tso lom week

Lub hydrophobic nyhuv uas governs lub cwj pwm ntawm cov hydrocarbon nyob rau hauv dej, tswj lug tsim los ntawm daim nyias nyias lipids thiab daim nyias nyias proteins. Muaj ntau daim nyias nyias zog conferred muaj lipid lis-khaubncaws sab nraud povtseg, txoj kev ua ib lub hauv paus qauv rau tag nrho cov lom week. Integral membrane proteins uas cov muab zais rau hauv cov lipid lis-txheej. Transmembrane cov nqaijrog muaj ib tug tshwj xeeb lub koom haum ntawm cov amino acids nyob rau hauv lawv cov thawj theem zuj zus.

Peripheral membrane cov nqaijrog yog heev uas zoo sib xws rau soluble, tab sis lawv kuj txuas mus rau lub week. Tshwj Xeeb cell week yog tshwj xeeb cell muaj nuj nqi. Raws li cov qauv thiab cov kev khiav dej num ntawm cell week muaj ib feem nyob rau hauv lub cev? Yuav ua li cas los mus tsim lom week nyob rau kom ntseeg tau lub functionality ntawm tag nrho cov kab mob. Los ntawm intracellular organelles, extracellular thiab cell-cell kev sib tshuam, membrane lug yog tsim nyog rau cov koom haum thiab cov kev kawm kev lom zog. Muaj ntau ntawm cov yam ntxwv thiab tej nta cov kev ua kab mob, eukaryotic hlwb thiab enveloped kab mob. Tag nrho lom week tsev rau ntawm qhov lipid lis-txheej, uas ua rau lub xub ntiag ntawm ib tug xov tooj ntawm ntau yam ntxwv. Membrane cov nqaijrog muaj ib tug ntau yam ntawm tej kev khiav dej num.

• Ntawm lwm yam uas. Cov ntshav daim nyias nyias ntawm lub hlwb txhais rau ib thaj tsam ntawm cell sis raug zoo nrog cov ib puag ncig.
• Tsheb thauj mus los. Intracellular membrane cell faib ua ob peb haumxeeb blocks nrog txawv nrog muaj pes tsawg leeg, txhua tus uas yog txhawb los ntawm cov kev tsim nyog thauj muaj nuj nqi nyob rau hauv nrog cov tswj permeability.
• Teeb liab transduction. membrane fusion muaj ib tug mechanism rau intracellular vesicular ceeb toom thiab tiv thaiv kom tag nrho cov xaiv ntawm cov kab mob dawb do nkag mus rau ntawm tes.

Tus nqi thiab cov lus xaus

Tus qauv ntawm lub txheej membrane ntawm lub cell muaj feem xyuam rau tag nrho lub cev. Nws plays ib qho tseem ceeb luag hauj lwm nyob rau hauv kev tiv thaiv lub sam xeeb, uas allergic ntawm tsuas xaiv cov ntaub ntawv. Nws kuj yog ib tug zoo puag rau kho cov cytoskeleton thiab lub cell phab ntsa, uas yuav pab nyob rau hauv kev tswj ntawm tes zoo lawm. Lipids roos txog 50% ntawm qhov loj ntawm lub membrane ntawm feem ntau lub hlwb, Txawm tias qhov no mas nws txawv nyob ntawm seb lub hom membrane. Tus qauv ntawm lub txheej cell daim nyias nyias ntawm cov tsiaj yog ntau yooj yim, muaj muaj plaub yooj yim phospholipid. Ib qho tseem ceeb khoom teejtug uas yog cov lipid lis-khaubncaws sab nraud povtseg yog hais tias lawv coj raws li ob-dimensional kua nyob rau hauv uas tus neeg molecules yog free tig thiab txav mus nyob rau hauv sab lus qhia. Qhov no fluidity - qhov no yog ib qho tseem ceeb cov khoom teejtug uas cov daim nyias nyias, uas yog txiav txim nyob ntawm kub thiab lipid muaj pes tsawg leeg. Vim hydrocarbon nplhaib qauv cholesterol plays ib tug luag hauj lwm nyob rau hauv kev txiav txim membrane fluidity. Selective permeability kev lom week me me molecules tso cai rau lub cell saib xyuas thiab tuav nws nrog cov qauv.

Xav cov qauv ntawm cov hlwb (cell daim nyias nyias, nucleus, thiab thiaj li nyob), peb yuav xaus uas tus kab mob - nws yog nws tus kheej-regulating system uas ib leeg xwb yuav tsis ua mob rau koj tus kheej thiab yuav nco ntsoov nrhiav txoj kev los kho thiab tiv thaiv cov hauj lwm ntawm txhua txhua cell.