Biology 1202B Lecture Notes - Lecture 2: Electrochemical Gradient, Signal Transduction, Phosphatase
11 Jan 2016
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Sometimes molecules are too big to move through a transmembrane protein. Membrane bound vesicle contains molecules to be removed/secreted from cell. Membrane recycling, this secretory vesicle came from the er. Cells bring in macromolecules too large for transmembrane import. Mutation of a single gene can specifically block facilitated diffusion but not simple diffusion . True this is because membrane bound proteins, if mutated can specifically block it. Simple diffusion is just across the membrane and does not require a transporter. Unlike simple diffusion, the rate of facilitated diffusion can become saturated by substrate . True, can be saturated, eventually the transporter proteins will be saturated, at a certain point there will be a plateau. Simple diffusion molecules do not bind and just move through across the membrane. One of the characteristics of life is the ability to respond to changes in the environment. Directly from the environment in single-celled organisms.
