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20 Cards in this Set

  • Front
  • Back
Cellilar Membrane
Fluid mosaic structure of lipids, proteins, and some are linked to carbohydrates
Lipid
(include)
phospholipid bilayer
Cholesterol
Glycolipid
Phospolipid bilayer
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)
Cholesterol
structural component of cell membranes (fluidity and permiability)
Also, physiological functions when tranformed to stroid hormones
Glycolipid
Recognition signals between cells
Membrane fluidity:
Phospholipids
move laterally in membrane
flip-flop is rare
Membrane fluidity:
Unsaturated hydrocarbon tails
tails of phospholipids have kinks keeping molecules form packing together
enhances membrane fluidity
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
Proteins
(types)
Integral Membrane Proteins
Integral transmembrane Protiens
Peripheral Membrane Proteins
Integral Membrane Proteins
Penetrate hydrophobic core of lipid bilayer.Hydrophilic region (domain) contain hydrophilic amino acids (polar) which interact with aqueous cytoplasm or external environment.
Integral Transmembrane Proteins
Hydrophobic region (domain) contain hydrophobic amino acids (a- helix) and are embedded in fatty-acids
Peripheral Membrane Proteins
Do not have hydrophobic region, so are not embedded in fatty acid. Only hydrophillic region (domain) that interact with other proteins.
Major Function of Membrane Proteins
Intercellular joining (adhesion)
Cell-cell recognition
Attachment to ECM
Transport
Enzymatic Activity
Signal Transduction
Cell-cell Recognition
The surface carbohydrates (glycoproteins and glycolipids) on cell plasma membrane serve for (1)recognition
Cell-cell Adhesion
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
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.
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
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
Desmosome
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
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