Cell Membranes and Cell Cell Membranes and Cell Transport LectureTransport Lecture

Cell DiversityCell Diversity

General Structure of CellsGeneral Structure of Cells

Cell Membrane Protects the Cell Membrane Protects the CellCell

Cell Membrane StructureCell Membrane Structure

Phospholipid Bilayer

Proteins in Cell MembraneProteins in Cell Membrane

These are the “windows” and These are the “windows” and “doors” of the cell.“doors” of the cell.

Cell Membrane Controls What Enters/Leaves the Cell

Membrane Proteins Form Membrane Proteins Form ChannelsChannels

Membrane Proteins Act as Membrane Proteins Act as ReceptorsReceptors

Membrane Proteins Connect Membrane Proteins Connect Cells TogetherCells Together

Membrane Proteins Allow Membrane Proteins Allow Cells to CommunicateCells to Communicate

Cholesterol in Cell MembraneCholesterol in Cell Membrane

Glycoproteins and Glycolipids Glycoproteins and Glycolipids in Cell Membranein Cell Membrane

Membrane TransportMembrane Transport

Cell membranes allow Cell membranes allow materials to enter or leave materials to enter or leave the cellthe cell

Lumpof sugar

Diffusion

No net movement at equilibrium

Random movement leads to net movement down a concentration gradient

Water

DiffusionDiffusion

Diffusion Animation

DiffusionDiffusion

Osmosis:Osmosis:Diffusion of water

across a cell membrane

Osmosis Animation

Shriveled cells Normal cellsCells swell andeventually burst

Hyperosmoticsolution

Isosmoticsolution

Hypoosmoticsolution

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Human Red Blood Cells

Outside

Plasmamembrane

Inside

Transport Protein

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- __Facilitated Diffusion

Facilitated DiffusionFacilitated Diffusion

Facilitated Diffusion AnimatiFacilitated Diffusion Animationon

A Channel Protein

H+

H+

Carrier ProteinCarrier Protein

Facilitated Diffusion with a Carrier Protein

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Outside of cell

Inside of cell

Active transport

Active TransportActive Transport

Sodium Potassium Pump Animation

EndoctytosisEndoctytosisPhagocytosisPhagocytosisPinocytosisPinocytosisReceptor-Mediated Receptor-Mediated EndocytosisEndocytosis

Phagocytosis

The substance engulfed is a solid particleThe substance engulfed is a solid particle

Process of PhagocytosisProcess of PhagocytosisSubstance engulfed is a solid particle

Pinocytosis

TheThe substance engulfed is a liquidsubstance engulfed is a liquid

Receptor-Mediated Endocytosis

Particles join to specific receptors on the Particles join to specific receptors on the membrane causing it to indent, membrane causing it to indent, engulfing the particles in a vesicleengulfing the particles in a vesicle

Transport of CholesterolTransport of CholesterolReceptor Mediated Receptor Mediated

EndocytosisEndocytosisPhospholipid outer layer

LDL particle

Cholesterol

Protein

Plasmamembrane

Receptorprotein

Vesicle

Cytoplasm

ExocytosisExocytosis The reverse of endocytosisThe reverse of endocytosis During this process, the membrane of a During this process, the membrane of a

vesicle fuses with the plasma membrane vesicle fuses with the plasma membrane and its contents are released outside the and its contents are released outside the cell:cell:

ExocytosisExocytosis