plasma membrane structure and transport
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Phospholipid Molecules
• The cell membrane is a phospholipid bilayer with proteins, lipids and carbohydrates.
Figure 3.3
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Phytosterols
bacterial
animal
Lipids bilayer is fluid
• Lipids of the bilayer fluid or liquid-crystalline state• Proteins move within the membrane
Membrana asimétrica
Triglicéridos
Adaptación homeoviscosa en composición de membranasde poikilotérmicos
Figure 3.3
• The cell membrane is a phospholipid bilayer with proteins, lipids and carbohydrates.
Figure 3.3
Membrane Protein Synthesis
Membrane proteins functions
Figure 3.4
Fig. 5-10a, p. 114
Integrin
(a) Anchoring. Somemembrane proteins, suchas integrins, anchor thecell to the extracellularmatrix; they also connect tomicrofilaments within the cell.
Outsidecell
Insidecell
Fig. 5-10g, p. 114
Insidecell 2
(g) Intercellular junction.Cell adhesion proteinsattach membranes ofadjacent cells.
Insidecell 1
Fig. 5-10b, p. 114
Outsidecell
(b) Passive transport.Certain proteins formchannels for selectivepassage of ionsor molecules.
Insidecell
Fig. 5-10c, p. 114
Outsidecell
Insidecell
(c) Active transport.Some transport proteinspump solutes across themembrane, which requiresa direct input of energy.
Fig. 5-10d, p. 114
Outsidecell
Insidecell
(d) Enzymatic activity.Many membrane-boundenzymes catalyzereactions that take placewithin or along themembrane surface.
Fig. 5-10e, p. 114
Outsidecell
Insidecell
(e) Signal transduction.Some receptors bind withsignal molecules such ashormones and transmitinformation into the cell.
Fig. 5-10f, p. 114
Antigen
(f) Cell recognition.Some glycoproteins functionas identification tags. Forexample, bacterial cells havesurface proteins, or antigens,that human cells recognizeas foreign.
Outsidecell
Insidebacterial
cell
Antibody
Transport across membranes
Diffusion
Figure 3.18
• Movement of a substance from an area of high concentration to low
• Concentration gradient and electrochemical potential• (down and up the gradient)
Diffusion across the Cell Membrane
Figure 3.19
Cystic fibrosis transmembrane conductance regulator
Osmosis
Figure 3.20
Osmotic Pressure
Transport across the membrane
Passive TransportFacilitated Diffusion
Permeases
Figure 3.22
Uniport
Efecto alostérico y especificidad
Figure 3.23
Active Transport
Antiport
Gradientes de concentración
Gradientes electroquímicos
Figure 3.24
Secondary Active Transport
symport
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