Biology 1202B Lecture Notes - Lecture 1: Transmembrane Protein, Cell Membrane, Extracellular Fluid
31 Oct 2017
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Exocytosis: sometimes molecules are too big to move through a transmembrane protein, membrane bound vesicle contains molecules to be removed/secreted from cell. Vesicle fuses with plasma membrane at release. Plasma membrane infolds creating a vesicle: cells brings in macromolecules too large for transmembrane import, pinocytosis vacuole created around extracellular fluid. Cell drinking : receptor mediated endocytosis, transmembrane proteins recognize target molecule. Acquire bulk quantities of a specific molecule. At the cellular level this means perceiving and reacting to a signal: directly from the environment in single celled organisms, from the environment or from other cells in multi-cellular organisms. Signal to response: receptor specific for signal molecule (highly specific) Surface receptors: transmembrane (integral) proteins, extracellular signal binding domain. Binding causes conformational change in protein: transmission of signal through plasma membrane. Initiates first steps in signal cascade: triggers cellular response, signal travels through membrane. Signal transduction: the extracellular signal molecule does not enter the cell.
