BIO111

Membrana y transporte celular

Figureage 97

Cell interior

Plasma membranePlasma membrane

Outside cell 0.1 µm

Hydrophilic heads

Hydrophobic tails

(a) Phospholipids in water (b) Detergent in water

Figure 5-7Page 100

E-face

P-face

Cytosol

Extracellularfluid

E-face

P-face

(a)

(b)

Movimiento de fosfolípidos

Time

Glycoprotein

Hydrophilichelixa

Cholesterol

Carbohydratechain

Extracellular fluid

HydrophilicHydrophobic

CytosolPeripheral

protein

Carbohydratechains

Integralproteins

Glycolipid

Funciones de las proteínas de la membrana

AnclajeTransporte pasivoTransporte activoActividad enzimáticaComunicaciónReconocimientoUnión

OutsidecellOutsidecell

Insidecell

Integrin

Outsidecell

Outsidecell

Outsidecell

Insidecell

Insidecell

Insidecell

ATP

ADPP

Na+

(a) Anchoring (b) Passive transport

(d) Enzymatic activity(c) Active transport

Outsidecell

Insidecell

Outsidecell 1

Insidecell 2

Outsidecell

Insidebacterial

cell

HumanBcell

HumanBcell

Antigen

(e) Signal transduction (f) Cell recognition

(g) Intercellular junction

(g) Intercellular junction

Mecanismos de transporte celular

Difusión OsmósisDifusión facilitadaTransporte activoEndocitosisExocitosis

Difusión

1 2 3

Osmosis

Diferencia en concentración

Membrana selectiva

Presión osmótica

Figure 5-11Page 104

Net movementof water molecules

Pressure applied to piston to resist upward movement

Waterplussolute

Pure water

Watermolecule

Moleculeof solute

Selectivelypermeablemembrane

Solución isotónica

Solución hipertónica

Solución hipotónica

Outsidecell

Outsidecell

Outsidecell

Insidecell

Insidecell

Insidecell

No net watermovement

Net water movementout of the cell

Net water movementinto the cell

Isotonic solution Hypertonic solution Hypotonic solution

10µm

(a)

(b)

(c)

Figure 5-13Page 106

Plasmamembrane

Vacuole

Vacuolarmembrane(tonoplast)

CytoplasmPlasmamembrane

Vacuole

Nucleus(a) (b) (c)

Plasmólisis

Turgencia

Transporte activo

aPage 108

Higher

Higher

Lower

Lower

Outsidecell

Cytosol

Activetransportchannel

ATP

Sodi

umco

ncen

trati

on g

radi

ent

Pota

ssiu

mco

ncen

trati

on g

radi

ent

(a)

Outside cell Outside cell

Inside cell Inside cell

Lowconcentration

of solute

Highconcentration

of solute

Figure 5-15bPage 108

ATP

ADP

1. Three sodium ions bindto the transport protein

2. A phosphate group istransferred from ATP tothe transport protein

3. The transport protein under-goes a conformationalchange, releasing threesodium ions outside the cell.

6. The transport proteinreturns to its original shape:Two potassium ions arereleased inside the cell

5. The phosphate is released

4. Two potassium ions bindto the transport protein

(b)

Endocitosis

Figure 5-17Page 110

0.25µm

1. A vesicle approaches the plasma membrane

2. fuses with it and

3. releases its contents outside the cell.

Figure 5-18(1)Page 111

3. Lysosomes may fuse with the vacuoleand pour their potent enzymes onto theingested material.

2. The vacuole then pinches off inside thecell.

1. Folds of the plasma membrane surroundthe particle to be ingested, forming asmall vacuole around it.

Figure 5-18(2)Page 111

Nucleus

Lysosomes Large vacuole

Bacteria

Ingested bacteria

Glycogen (storednutrients)

2.5µ

m

Figure 5-19Page 111

Microvilli Pinocytotic vesicle

Cytosol

Figure 5-20aPage 112

Plasmamembrane

Cytosol

Uncoatedvesicle

Endosome

LDL receptor transportedto plasma membraneand recycled

Freecholesterol

Secondarylysosome

LysosomeClathrin

Clathrinrecycled

Coatedpit

LDLparticle

LDLreceptor

(a)

Figure 5-20bPage 112

0.25µm(b)

Fig. 5-23a, p. 126

Coatedpit

LDL attaches to specificreceptors in coated pitson plasma membrane.

Vesicle containing LDLparticles fuses with alysosome, forming asecondary lysosome.Hydrolytic enzymesthen digest cholesterolfrom LDL particles foruse by cell.

Endocytosis results information of a coatedvesicle in cytosol.Seconds latercoat is removed.

Uncoated vesiclefuses with endosome.

Receptors are returnedto plasma membraneand recycled.

(a) Uptake of low-density lipoprotein (LDL) particles, which transport cholesterol in the blood.

Endosome

Endosome

Primary lysosome

Clathrinrecycled

Secondarylysosome

Freecholesterol

Clathrin

Cytosol

Uncoatedvesicle

Plasmamembrane

LDLreceptor

LDLparticle

1

2

3

4

5

1

2

3

4

5

Exocitosis

Fig. 5-20, p. 124

Exocitosis

Ciclo Celular

Fig. 10-5, p. 215

INTERPHASE

G1 (First gap phase)

S (Synthesis phase)

G2 (Second gap

phase)

M PHASE (Mitosis and cytokinesis)

Fig. 10-6a, p. 216

Fig. 10-6b, p. 217