Phospholipid Molecules

• The cell membrane is a phospholipid bilayer with proteins, lipids and carbohydrates.

Figure 3.3

Colesterol 50% lípidos

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