Membrane TransportMembrane Transport

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membrane transport

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Cell Membrane aka Plasma MembraneCell Membrane aka Plasma MembraneCell Membrane aka Plasma MembraneCell Membrane aka Plasma Membrane

Outsideof cell

Insideof cell(cytoplasm)

Cellmembrane

Proteins

Proteinchannel Lipid bilayer

Carbohydratechains

• Composed of double layer of phospholipids and proteins (A phospholipid bilayerphospholipid bilayer)

• Surrounds outside of ALL cells• Is semipermeablesemipermeable• Watch This

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PhospholipidsPhospholipidsPhospholipidsPhospholipids

• Heads contain glycerol & phosphate and are hydrophilic (attract water)

• Tails are made of fatty acids and are hydrophobic (repel water)

• Make up a bilayer where tails point inward toward each other

• Can move laterally to allow small molecules (O2, CO2, & H2O to enter)

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The Cell Membrane is The Cell Membrane is FluidFluid

The Cell Membrane is The Cell Membrane is FluidFluid

FLUID MOSAIC MODEL: Molecules in cell membranes are constantly moving and changing

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Cell Membrane ProteinsCell Membrane ProteinsCell Membrane ProteinsCell Membrane Proteins

• Proteins help move large molecules or aid in cell recognition

• Peripheral proteins are attached on the surface (inner or outer)

• Integral proteins are embedded completely through the membrane

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Recognize “self”

GLYCOPROTEINSGLYCOPROTEINS

Glycoproteins have carbohydrate tails to act as markers for cell recognition

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•Lies immediately against the cell wall in plant cells

•Pushes out against the cell wall to maintain cell shape

Cell Membrane in PlantsCell Membrane in PlantsCell Membrane in PlantsCell Membrane in PlantsCell membrane

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Remember The Heterotroph Hypothesis?

Remember The Heterotroph Hypothesis?

Cell Membrane Forming Spontaneously?!

Two Forms Of Membrane Transport

Two Forms Of Membrane Transport

Concepts:

Equilibrium

Concentration gradients

Polarity

Molecule size

Electrical Charge

Passive vs. Active

Passive TransportPassive Transport

Passive transport requires no energy!

Diffusion - Movement from [hi] to [low]

Osmosis - Diffusion of water

Facilitated Diffusion - with carrier proteins

Active TransportActive Transport

Active transport requires energy

Ion Channels Ion Pumps Endocytosis

PhagocytosisPinocytosis

Exocytosis