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20 Cards in this Set
- Front
- Back
Cellilar Membrane
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Fluid mosaic structure of lipids, proteins, and some are linked to carbohydrates
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Lipid
(include) |
phospholipid bilayer
Cholesterol Glycolipid |
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Phospolipid bilayer
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composition of phosopholipid (PL) differs according to the memberanes surrounding cells and/or organells
(fatty acid length, saturated vs. unsaturated fatty acid, and polarity of the phosopholipid heads) |
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Cholesterol
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structural component of cell membranes (fluidity and permiability)
Also, physiological functions when tranformed to stroid hormones |
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Glycolipid
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Recognition signals between cells
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Membrane fluidity:
Phospholipids |
move laterally in membrane
flip-flop is rare |
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Membrane fluidity:
Unsaturated hydrocarbon tails |
tails of phospholipids have kinks keeping molecules form packing together
enhances membrane fluidity |
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Membrane fluidity:
Cholesterol |
reduces membrane fluidiy at moderate temperatures, by reducing phospholipid movement.
At low temperatures it hinders solidification by disrupting the regular packing of phospholipids |
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Proteins
(types) |
Integral Membrane Proteins
Integral transmembrane Protiens Peripheral Membrane Proteins |
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Integral Membrane Proteins
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Penetrate hydrophobic core of lipid bilayer.Hydrophilic region (domain) contain hydrophilic amino acids (polar) which interact with aqueous cytoplasm or external environment.
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Integral Transmembrane Proteins
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Hydrophobic region (domain) contain hydrophobic amino acids (a- helix) and are embedded in fatty-acids
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Peripheral Membrane Proteins
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Do not have hydrophobic region, so are not embedded in fatty acid. Only hydrophillic region (domain) that interact with other proteins.
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Major Function of Membrane Proteins
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Intercellular joining (adhesion)
Cell-cell recognition Attachment to ECM Transport Enzymatic Activity Signal Transduction |
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Cell-cell Recognition
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The surface carbohydrates (glycoproteins and glycolipids) on cell plasma membrane serve for (1)recognition
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Cell-cell Adhesion
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The surface carbohydrates (glycoproteins and glycolipids) on cell plasma memebrane serve for (2) adhesion
Other cells forming tissues/organs Infectious bactiria/Viruses Bonds are: Homotypic-same molecule Heterotypic-different molecule |
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Tight Junction
(Occluding Junction) |
located apically within lateral domain, involve occludin proteins
Encircle cell-seperate luminal space from intercellular space and connective tissue. Plasma membrane of adjacent cells come into contact and seal off intercellular space, forming an impermiable diffusion barrier between cells. Prevent migration of protein between apical and lateral surface. |
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Adhesion Junction
(Anchoring Junction) |
Maintain cell-cell adherance by linking transmembrane proteins on adjacent cells, resulting in a fusion of adjoining cell membranes
Two types of anchoring cell junctions: Adhesion Junction Desmosomes |
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Adhesion Junction
(Adhesion Junction) |
interact with actin filaments within cell
Composed of transmembrane adhesion molecule E-cadherin Intracellular tail of E-cadherin binds to B-catenin on cytoplasmic side of plasma membrane forming a cadherin-catenin complex cadherin-catenin bind to a-catenin and the actin cytoskeleton Continuos band or belt that completely encircle the cell |
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Desmosome
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Interact with intermediate filaments
Disk-shape structure at surface of one cell is matched with disk-shape of adjacent cell Wide intercellular space containing dense medial band of desmoglein Intermediate keratin filaments are inserted into attachment plaque and loop back towards cytoplasm which provides firm adhesion between cells |
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Communicating Junction
(gap junction) |
Coordinate activity between cells by permitting movement of ions or signaling molecules between cells
Accumulation of channels or pores in tight packed array Pores in one cell line up with pores of adjacent. Allows molecules, nutrients, ions, and signaling to pass/occur between cells Each pore consists of tubular structure- 6 connexins arrayed in circle pattern w/ transverse gap |