Download THE CELL MEMBRANE - Mrs. Guida's AP Biology Class

THE CELL MEMBRANE
CHAPTER 5
Fluid Mosaic Model
Fundamental Architecture of Cell
Membranes
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Phospholipid Bilayer
Transmembrane Proteins
Interior protein Network
Cell Surface Markers ( glycoproteins and
glycolipids)
How can we see the membrane?
• Electron Microscopy
• Freeze fracturing
Membrane Fluidity
• Saturated vs Unsaturated fats
• Bacteria
• Temperature
Proteins in the Membrane
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Transporters
Enzymes
Cell surface receptors
Cell surface identity markers
Cell-to-cell adhesion proteins
Attachments to the cytoskeleton
Transmembrane Domains
• Alpha Helices, span membrane at least once
Pores
• Betapleated sheets
Passive Transport Across
Membranes
• Moving Down a concentration gradient
• Diffusion
Proteins in Diffusion
• Channel Proteins
• Carrier Proteins
– Make membrane selectively permeable
Ion Channels
• Can be gates
• 3 conditions determine
net movement
– Concentrations across
membrane
– Voltage difference
– The state of the gate
Facilitated Diffusion
• Still Passive
• Diffusion rate depends on the amount of
available receptors
• Can reach saturation
• Specific to certain molecules or ions
• Found in RBCs (glucose and Chloride
HCO3)
Osmosis
• Movement of water
across membranes
• Solvents vs Solutes
• Osmotic
Concentration:Hyp
ertonic vs
Hypotonic vs
Isotonic
• Aquaporins
• Hydrostatic
Pressure
Methods of Maintaining Balance
• Extrusion- found in many single-celled
eukaryotes….contractile vacoules
• Isomotic Regulation- organisms that live in
the ocean
• Turgor- plant cells
Active Transport
• Uses Energy
• Moves against concentration gradient
• Uniporters vs symporters vs antiporters
Sodium Potassium Pump
Coupled Transport
• Uses ATP indirectly
• Uses the energy
created by another
transport to move a
molecule up their
concentration
gradient ex. glucose
Endocytosis
• Cell takes in materials
• Phagocytosis
• Pinocytosis
• Can be
Receptor
mediated
Exocytosis
• Material leaves the cell