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20 Cards in this Set
- Front
- Back
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Cell Membrane
Structure |
Phospholipid Bilayer with proteins, lipids and carbohydrates
Hydrophilic heads go outside and hydrophobic tails go to the inside 2 patterns - vesicular bilayers, spherical micelles or spherical globules |
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Membrane Lipids
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The lipid bilayer has and inner and outer layer
42% of membrane weight Choline phospholipids(lecithin) Sphingomyelin Ceramide Aminophospholipids Cholesterol |
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Membrane Lipids
Choline Phospholipids |
Lecithin
Predominate on the outer surface Associated with regulating points of lipid exchange across the membrane and metabolism by the cell |
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Membrane Lipids
Sphingomyelin |
Also a choline phospholipid, but with sphingosine alcohol replacing glycerol
Occupies the outer layer |
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Membrane Lipids
Ceramide |
Also within the bilayer
Oriented predominantly in the outer layer Resembles sphingomyelin except it lacks the choline |
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Membrane Lipids
Aminophospholipids |
Predominate on the inner bilayer
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Membrane Lipids
Cholesterol |
Occupies the area between the phospholipid bilayer
In a 1:1 molar ratio with the other phospholipids - disrupting this ratio has fatal consequences for the cell - in the RBC it leads to a distortion of the membrane and shape change which causes death of the cell |
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Membrane Proteins
Types |
Integral proteins
Peripheral Proteins Anchoring Proteins Recognition Proteins Enzymes Receptor Proteins Carrier Proteins Channel Proteins |
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Membrane Proteins
Integral Proteins |
Are part of the membrane structure
Provide structural support Span the entire width of thee membrane Cannot be separated from the membrane without destroying it Also called transmembrane proteins They unify the lipid bilayer with the cytoskeleton Outnumber the peripheral proteins |
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Membrane Proteins
Peripheral Proteins |
Bound to the inner or outer surface of the membrane
Can easily be separated from the membrane Connect with integral proteins to unite the protein/phospholipid moiety Provide support and shape to the cell Many have a functional role |
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Membrane Proteins
anchoring Proteins |
Attach the cell membrane to other structures
Stabilize the cell in position Inside cell anchoring proteins are bound to the cytoskeleton Ankyrin is an anchoring protein |
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Membrane Proteins
Recognition Proteins |
Identify tissue as self or foreign, normal or abnormal
Ex: MHC molecules ssociated with immunity |
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Membrane Proteins
Enzymes |
Catalyze reactions
Maintain other membrane proteins in a viable state |
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Membrane Proteins
Receptor Proteins |
Accept ligands(specific extracellular molecule) that trigger changes in the activity of a cell
Ligands can be simple ions to complex hormones |
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Membrane Proteins
Carrier Proteins |
Type of integral protein
Bind solute Change shape carrying solute across the cell membrane where it is released Carrier protein then returns to its original shape May require ATP Needs ATP to transport sodium out of cell Does not need ATP for glucose uptake |
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Membrane Proteins
Channel Proteins |
Type of integral protein
Contains a central pore or channel Permits the movement of water, ions, and other small water-soluble solutes Certain channels are highly selective in the ions they channel Highly selective - ? 3 anionic exchange channel proteins for Cl- and HCO3- pass with great freedom and resist the movement of cations Na+ ions have a 30 hour 1/2 time exchange rate |
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Membrane Carbohydrates
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Roughly 3% of the weight of the plasma membrane
Components of proteoglycans, glycolipids, and glycoproteins Carbohydrate portion of the large molecules extend beyond the outer and inner surfaces forming a layer known as the glycocalyx |
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Glycocalyx
Functions |
Lubrication and protection of membrane
Anchoring cell in place and locomotion of specialized cells Specificity in binding function as receptors Recognition - glycoprotein and glycolipids are recognized as normal or abnormal by cells in the immune system |
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Cell Membrane
Functions |
Physical isolation
Regulation of exchange with the environment Sensitivity to the environment Structural support |
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Fluid Compartments
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Intracellular - within the cell
Extracellular - outside the cell Interstitial space - space between (inter) tissues (stitial) cells; this space contains interstitial fluid Intravascular - within vessel (contains blood or lymph) Extravascular - outside the vessel; this places you in the interstitial fluid |
