Biology 1202B Lecture Notes - Lecture 1: Transmembrane Protein, Cell Membrane, Extracellular Fluid
25 May 2016
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Document Summary
Sometimes molecules are too big to move through a transmembrane protein. Membrane bound vesicle contains molecules to be removed/secreted from cell. Secretory vesicle approaches plasma membrane: vesicle fuses with plasma membrane, proteins inside the vesicle are released into the cell exterior, and then the proteins in the vesicle membrane become part of the plasma membrane. Cells brings in macromolecules too large for transmembrane import. Constant: solute molecules and water molecules are outside the plasma membrane, membrane pockets inwards, enclosing molecules, pocket pinches off as endocytic vesicle. Receptor mediated endocytosis: transmembrane proteins recognize target molecule. Acquire bulk quantities of a specific molecule: substances attach to membrane receptors, membrane pockets inwards, pocket pinches off as endocytic vesicle. One of the characteristics of life is the ability to respond to changes in the environment. At the cellular level this means perceiving and reacting to a signal. Directly from the environment in single celled organisms.
