BIO 328 Lecture Notes - Lecture 2: Lipid Bilayer, Semipermeable Membrane, Chemical Polarity
7 Aug 2018
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Document Summary
The first cells protocells - cell membrane defines intracellular/extracellular space - darwinian evolution. When the first cell membrain first evolved, dawrin applied it. Physical constraints on protocells: permeability of lipid bilayer - first cells leaky membrane - more transporters required as membrane becomes less leaky. Deffusion was important for the first cell. Permeability of lipid bilayer useful solute they would tap there and cant diffusion out of the cell: diffusion - first cells were very small - high surface to volume ratio - diffusion times generally constrain cell size. Cal salt insoluble . phosphates in nuclic acids, protiens. The first cells devolped with low cal consetration. Had to figure out before moving out to make sure too much cal would kill them. Minimal cell physiological properties mammual cells: regulate membrane permeability, regulate internal calcium concentration, regulate internal ph, regulate cell volume - osmolality - high internal k+ ion concentration.
