BIOLOGY 2EE3 Lecture Notes - Lecture 6: Lipid Bilayer, Cell Membrane, Hopanoids
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19 Dec 2019
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In most bacteria the cell envelope is composed of the plasma membrane, a semi-rigid cell well composed of peptidoglycan and an outer membrane. The outer membrane is an important distinction between two different types of bacteria. Plasma membrane is directly adjacent to the cytoplasm and keeps it inside. The plasma membrane is ubiquitous to all cells found in all cells, not just bacteria. Composed of a phospholipid bilayer with integral membrane proteins: hydrophilic heads and hydrophobic centre: the heads point towards through the aqueous environment of the cytoplasm as well as extracellular fluid, tails point toward each other (hydrophobic interactions) Fluid mosaic : free lateral movement through the membrane; not a rigid structure: has cholesterol molecules called hopanoids that stabilizes the membrane, proteins act in bilayer in a fluid-manner, it is not static. S t e r o l s: bacterial membranes lack sterol lipids used by eukaryotes to stabilize the membrane.