Bio 201 1st Edition Lecture 14 Outline of Last Lecture I. Multicellular StructuresA. Cell AdhesionsB. Extracellular MatrixII. Membrane PermeabilityOutline of Current LectureI. Transmembrane TransportA. Simple DiffusionB. Facilitated DiffusionC. Active TransportCurrent LectureI. Transmembrane Transport- Things that get moved across membrane. 3 types:A. Simple Diffusion- Diffusion of small, uncharged molecules across membrane from high to low concentrations, down concentration gradient. These molecules pass freely eventually allowing concentration to equilibrate. Ex) Gas exchange in lungs of 02 into blood and CO2 out of blood. B. Facilitated Diffusion- Diffusion down concentration gradient through protein transporter. Molecules that cannot pass freely through membrane use this. Transport molecules are designed to bind to and move these molecules into cells. 1.) Ion Channels- Gated channels that open in response to either a ligand or voltage change. Upon opening, selected ions diffuse down its concentration gradient through the channel. 2.) Carrier Proteins- Provide a conduit for molecules that would not ordinarily diffuse through membrane. Ex) Glucose binds to transporter (GLUT1), GLUT1 conformational change opens to interior of cells, glucose dissociates into cytoplasm. This does not require energy, therefore, these can flow in or out.C. Active Transport- Moves up concentration gradient, low to high. Requires energy. These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.1.) Source of Energy: -Direct- uses energy from ATP hydrolysis -Indirect- uses energy from another molecule moving down concentration gradient2.) Transport?-Uniport- one molecule moves-Symport- 2+ molecules move in same direction-Antiport- 2 molecules move in opposite directions -The most important protein for direct active transport is Na/K ATPase. ATPase catalyzes hydrolysis of ATP. Continually pumps Na out and K into cell, the ATP provides energy.-The most important indirect active transport protein is Na/ glucose symporter. Only possible by using the energy stored by the concentration gradient. Diffusion of Na down its concentration releases energy. Glucose tranportsup the concentration gradient requires energy. Energy of Na diffusion is captured as kinetic energy by transporter which allows it to “push” glucose up its concentration gradient. Sodium gradient is essential for indirect active transport of most
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