Cell Membrane Structure and Function: A Comprehensive Analysis
8.LA cell membrane: a structural unit
1.LA plasma membrane as a structural unit: the plasma membrane is a selective barrier, has the same structure in every cell, so q is called the unit membrane, lipid bilayer membranes as a unit. 2 composition of the plasma membrane: lipid and proteins. 2. Membrane Lipids 1: 1. Phospholipids: polar head and apolar tail, 2. Glycolipids: Only found in the outer face of the plasma membrane, 3.Esteroides: derivatives of cholesterol in animal cells. . 2.2 Membrane Proteins: 1. Integrals associated with the membrane bound x the van der Waals bond, 2. Perifericas: weak links. The membranes are asymmetric, q inner and outer faces have a different composition. 3 Models Membranes: fluid mosaic model. membrane fluidity x several factors: 1. Degree of saturation of fatty acids: maoyr decreases the fluidity is the degree of saturation, 2. length of the fatty acid chains: the fluidity decreases with increasing length, 3. Temperature: the fluidity decreases as the temperature drops q 4. Ratio of cholesterol: q rigid molecule stabilizes the membranes, the less fluid you.
4.FUNCIONES cell membrane: a selective Barerra features: 1. Production of gradients, 2. Exchange of signals, 3. Cell division (the membrane is involved in the control), 4. Cellular immunity, 5. Endocytosis and exocytosis.5.TRANSPORTE of molecules across membranes: cell membranes are smipermeables: 1. Some lipid-soluble molecules can cross the membrane freely, 2. The protein molecules used to transport cargo. 5.1 Passive transport: gradient for without energy expenditure: 1. Difusion simple: direct x 1 / 2 channel protein, 2. Difusion provided: It is moved out x q-proteins molecular polar high specificity for the transport of a certain type. 5.2Active Transport: against the gradient requires energy expenditure. Na + / ka +: 3Na + and enter eject 2KA + trnsmision important for nerve impulse and what makes a protein ATPH. Pump ca2 +: ca2 + ions ejected from the endoplasmic reticulum and spends ATP is important in muscle cells. 6. DIFFERENCES IN THE MEMBRANE: 6.1MIcrovellosidades: Extensions of certain cell surface q increase absorption. 6.4 junctions: 1. Junctions of adhesion (desosomas in epiteriales cells), 2. Junctions impermeable (cells of instestino), 3. communication connections (channels allow the passage of protein molecules)