Transcript Cell Membrane aka Plasma Membrane

Membrane Transport
Pages 78-85 include
information on
membrane transport
Cell Membrane aka Plasma Membrane
• Composed of double layer of phospholipids and
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•
•
proteins (A phospholipid bilayer)
Surrounds outside of ALL cells
Is semipermeable
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Outside
of cell
Proteins
Carbohydrate
chains
Cell
membrane
Inside
of cell
(cytoplasm)
Protein
channel
Lipid bilayer
2
Phospholipids
• 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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3
The Cell Membrane is Fluid
FLUID MOSAIC MODEL: Molecules in cell membranes
are constantly moving and changing
4
Cell 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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5
GLYCOPROTEINS
Recognize
“self”
Glycoproteins have carbohydrate tails to act
as markers for cell recognition
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6
Cell Membrane in Plants
Cell membrane
• Lies immediately
against the cell
wall in plant cells
• Pushes out
against the cell
wall to maintain
cell shape
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7
Cell Membrane Forming Spontaneously?!
Remember The Heterotroph
Hypothesis?
Two Forms Of Membrane
Transport
Concepts:
Equilibrium
Concentration
gradients
Polarity
Molecule size
Electrical Charge
Passive vs. Active
Passive Transport
Passive transport requires no energy!
Diffusion - Movement from [hi] to [low]
Osmosis - Diffusion of water
Facilitated Diffusion - with carrier proteins
Active Transport
Active transport requires energy
Ion Channels
Ion Pumps
Endocytosis
Phagocytosis
Pinocytosis
Exocytosis