Flashcards on Biomembranes and Membrane Transport Mechanisms
Biomembranes and Membrane Transport Mechanisms Explained for Students
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Membrane transport
50 cards
Card 1
Question: What is passive transport and what drives diffusion of charged molecules across a membrane?
Answer: Passive transport is movement down gradients without energy input. Diffusion of charged molecules is influenced by the gradient of electric potential
Card 2
Question: Write the general form of the Nernst–Planck relation for mass flux J_M given concentration and electric potential gradients (symbols from the content)
Answer: J_M = L_MC · F_C + L_Mu · F_U where J_M is mass flux, L_MC and L_Mu are thermodynamic coefficients, F_C is concentration gradient and F_U is electric
Card 3
Question: How is one-dimensional diffusive mass change expressed in the provided content (give the differential equation and define symbols)?
Answer: dm/dt = -A·D·(dc/dx) + z·F·c·(R·T)^{-1}·(dφ/dx) where A is area, D diffusion coefficient, dc/dx concentration gradient, z charge, F Faraday constant,
Card 4
Question: Define osmosis according to the content.
Answer: Osmosis is diffusion of solvent molecules across a semipermeable membrane from lower to higher concentration of osmotically active compounds (toward h
Card 5
Question: What is osmolarity and what are its units?
Answer: Osmolarity is the number of osmotically active particles in one liter of solution. Units: osmol/L.
Card 6
Question: What is osmolality and what are its units?
Answer: Osmolality is the number of osmotically active particles in one kilogram of solution. Units: osmol/kg.
Card 7
Question: What is the normal (isotonic) osmotic value given in the content?
Answer: Normal osmotic (isotonic) value is 280–300 mOsmol/kg.
Card 8
Question: State van 't Hoff's relation for osmotic pressure for ideal liquids and define symbols.
Answer: π = c·R·T where π is osmotic pressure, c is molar concentration, R is molar gas constant, and T is absolute temperature.
Card 9
Question: How is van 't Hoff's relation modified for real solutions in the provided content?
Answer: For real solutions: π = i·c·R·T where i is van 't Hoff's correcting coefficient (i ≥ 1).
Card 10
Question: Define active transport and list the energy sources mentioned.
Answer: Active transport moves substances against their electrochemical gradient and requires energy. Energy sources: ATP hydrolysis (primary active transport