biomembranes and cell architecture

biomembranes and cell architecture

1. Architecture

   • Prokaryotes
     • No organels, but do contain plasma membrane
       • metabolites are thought to diffuse freely
       • primitive cytoskeleton in some bacterias
   • Eucaryotes
     • organels to develope its functions and plasma membrane
       • unique complement of proteins in every organel
       • nucleus and other organels in all cells
         • Nucleus
           • houses the genome of the cell
         • Endosomes
           • internalize plasma membrane proteins and soluble materials from the extracellular medium
         • Lysosomes
           • degrades worn.out or unneeded cellular components
         • peroxisomes
           • oxidize compunds that do not involve ATP process
         • mitochondrias
           • multiple functions for the cell including one of the most important process (production of atp)
         • chloroplasts (in plant cells)
           • absorbs light for the atp production of the plant
         • Cytosol
           • 3 mayor proteins
             • actin filaments, microtubules, and intermediate filament
               • Cytoskeleton
                 • Structure and stability for the cell

2. Biomembranes

   • made of
     • A phospholipid bilayer
       • its principal compounds are
         • -phosphoglycerides, sphingolipids and steroids
       • lipids and many proteins are laterrally mobile in membranes
         • Lipid rafts
           • sites for signaling across the membrane
       • Proteins
         • integral and peripheral proteins
           • integral proteins
             • usually contain
               • hydrophobic and hydrophilic domain
                 • from the cytosolic and exoplasmic faces of the membrane
               • Porins
                 • Barell-like channel through the membrane
           • peripheral proteins
             • interact with integral proteins
             • Are in the membrane "temporarily"