Lecture 5: Membrane Transport// IAHSS ADVANCED OFFICER CERTIFICATIONS EXAMS |ACCURATE TESTING VERSIONS

At rest, is the inside of the cell negatively charged or positively charged? - ANSWER-negative At rest, what is the concentration gradient of Na+ and of K+? If we allow these ions to move, where will they move? - ANSWER--Most cells have a negative membrane potential as a result of uneven distribution of ions on either side of the membrane -This is important because it creates a chemical gradient, where some ions are higher on one side than the other -channels move materials down the concentration gradient What are the three types of membrane transport? - ANSWER--diffusion (through the membrane) -channels (non-gated or gated) -carriers (facilitators or pumps) Which type of membrane transport require energy? - ANSWER-pumps (active) require energy Why can't everything diffuse across the membrane? - ANSWER--small, non polar molecules can diffuse across the lipid bilayer (CO2, O2, H2O) -ions and larger uncharged molecules cannot diffuse across (glucose) Do channels require energy? How about pumps? - ANSWER-Channels do not require energy but pumps do What are the three different ways that we can control when a channel is open or closed (i.e. gating)? - ANSWER--voltage gated (change in membrane potential) -ligand gated (specific chemical substance) -mechanically gated (physical force on the membrane) What component of a voltage-gated channel structure creates a selectivity to specific ions? - ANSWER-P-loop is