28513020
| Pregunta | Respuesta |
| Cell/Plasma membrane functions | • Physical and protective barrier • Regulate transport • Allow cell-recognition and cell communication • Mechanical properties (continuity, capacity for movement and expansion) • Internal membrane (eukaryotes) (enclosing an intracellular compartment, differences in protein membranes – responsible for giving each organelle its distinctive character) |
| Vilken fosfolipid är vanligast? | phosphatidylcholine |
| 3 main types of membrane lipids | - phospolipids - cholesterol - glykolipid |
| På vilka sätt kan lipid molekylerna flytta på sig i membranet? | Lateral difussion Flexion Rotation Flip-flop |
| Hur påverkar längden på fettkedjan fluiditeten? | Längre => mer interaktioner => mindre flytande |
| Hur reguleras fluiditeten hos djurceller? | Av kolesterol |
| Var syntetiseras nya membran lipider? | På cytosol sidan av ER |
| scramblase | Flyttar fosfolipider mellan de båda lagrena för att få en symmetrisk form |
| Flippases | flyttar specifika fosfolipider mellan de båda lagrena => assymetriskt cellmembran med olika typer av lipider på båda sidorna |
| Orientation of membrane proteins is... | crucial for their function |
| Var finns glykolipiderna? | Uteslutande i icke-cytosol lagret |
| Vilka molekyler kan ta sig genom cellmembranet och vilka kan inte det? | Kan ta sig igenom: - små opolära molekyler - väldigt små polära (oladdade molekyler) Kan inte ta sig igenom: - större opolära molekyler - laddade molekyler |
| Vad har membran proteinerna för funktion? | Transportprotein, receptorer, enzym, "anchor" |
| På vilka olika sätt kan proteiner vara "fästa" i membranet? | Integral membrane proteins: Transmembrane, monolayer associated alfa helix, lipid-linked Peripherical membrane proteins: proten-attached |
| Cell cortex | The cell cortex, also known as the actin cortex or actomyosin cortex, is a specialized layer of cytoplasmic protein on the inner face of the plasma membrane of the cell periphery. It functions as a modulator of plasma membrane behavior and cell surface properties. Meshwork of fibrous proteins attached to the membrane via transmembrane proteins |
| Glykocalyx | carbohydrate layer Sugar coat at the non-cytosolic (extracellular) side Glycolipids glycoproteins proteoglycans Functions: Protection cell surface from mechanical and chemical damage/stress Important in cell-cell recognition and cell-adhesion |
| Types of membrane transport proteins: | - Transporters - Channels Active transport (pumps) passive transport |
| Electrochemical gradient | = net driving force = sum of the force from the concentration gradient of a solute and the force from the membrane potential |
| Glucose transporter | passive |
| Na+/K+ pump | 3 Na+ ut 2 K+ in ATP driven |
| Ion selectivity depends on: | diameter and shape of the ion channel distribution of charged amino acids of the channel |
| Gap junctions | Large channels between 2 cells to provide electrical and metabolic coupling |
| Different types of ion channels depending on stimuli for opening the gate | Voltage gated ligand- gated (extracellular ligand) (något binder in) ligand-gated (intracellular ligand) mechanically gated |
| active signalling mechansim | ... |
| Action potential | Stimulus →membrane potential of the plasma membrane becomes less negative →opening of additional voltage-gated Na+ channels = depolarization causes Na+ influx →At ca +40 mV electrochemical driving force for Na+ is zero = no more influx of Na+ → return to resting potential by opening of voltage-gated K+ channels = repolarisation = K+ efflux |
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