Module 4 Quiz

Simple Diffusion is the movement of nonpolar compounds down their concentration gradient, where as, osmosis is the movement of water

The free energy change is determined by the concentration difference (C1-C2).

Passive transport involves the movement of molecules down their concentration gradient, without the use of energy hence making it a spontaneous process.

<p>The formula for free energy change (ΔG) for the transport of uncharged solutes from concentration C1 to C2 is ΔG = ΔG0' + RT ln ([P]/[S]), where R is the gas constant, T is the temperature in Kelvin, and ln represents the natural logarithm. [P] and [S] represent the concentrations of the solute on the two sides of the membrane.</p> Signup and view all the answers

<p>Polar compounds and ions cannot cross the membrane unassisted due to the hydrophobic nature of the lipid bilayer. They require specific membrane protein carriers to facilitate their transport across the membrane.</p> Signup and view all the answers

<p>kJ.mol-1.K-1</p> Signup and view all the answers

<p>Size, polarity, ionicity</p> Signup and view all the answers

<p>100:1</p> Signup and view all the answers

<p>Bilayers are more permeable to nonpolar molecules.</p> Signup and view all the answers

<p>Shuttles K+ ions</p> Signup and view all the answers

<p>They kill other cells by dissipating their ion gradients</p> Signup and view all the answers

<p>Transporters lower the activation energy by binding solutes via weak, noncovalent interactions, which counteracts the positive ΔG of dehydration, thereby forming a transmembrane pathway lined with polar amino acids.</p> Signup and view all the answers

<p>k is inversely and exponentially related to ΔG‡</p> Signup and view all the answers

<p>Transporters bind their substrates through non-covalent interactions, are saturable, and have a gate on either side of the membrane that is never open at the same time, whereas ion channels provide an aqueous path through the membrane for inorganic ions to diffuse.</p> Signup and view all the answers

<p>The transition state is a high-energy intermediate state that is similar in both enzyme-catalyzed reactions and facilitated transport, requiring an energy input (activation energy, ΔG‡) to overcome the energy barrier.</p> Signup and view all the answers

<p>Because they are saturable, meaning that the rate of transport does not increase significantly above a certain concentration of substrates.</p> Signup and view all the answers

<p>Gramicidin A is a β-helical peptide that forms a dimer, creating a channel with a 0.4 nm pore, allowing monovalent cations like Na+ and K+ to pass through.</p> Signup and view all the answers

<p>The energy barrier is the activation energy required to transport a polar or charged solute across a membrane, involving the stripping of hydration layers and movement across the non-polar membrane environment.</p> Signup and view all the answers

<p>The β6.3 helix is a tertiary structure that forms a wide channel, allowing ions to pass through.</p> Signup and view all the answers

<p>Gramicidin A forms a channel in the bacterial membrane, allowing ions to pass through and disrupting the bacterial membrane potential, ultimately leading to bacterial death.</p> Signup and view all the answers

<p>cyclic structure of L-lactate, D/L-valine, D-hydroxy-isovalerate</p> Signup and view all the answers

<p>k+ binds to the size-selective cavity of valinomycin through carbonyl coordination, which shields charges.</p> Signup and view all the answers

<p>its a compound that shuttles an ion (K+) across the membrane</p> Signup and view all the answers

<p>When K+ is bound to the valinomycin cavity, its non-polar groups interact with acyl chains to form a lipid-soluble complex that shuttles the ion across the membrane.</p> Signup and view all the answers

<p>A type of peptide in which one or more of the amide group is replaced with an ester.</p> Signup and view all the answers

<p>analogous</p> Signup and view all the answers

<ul> <li>osmosis</li> <li>simple diffusion</li> <li>facilitated diffusion</li> </ul> Signup and view all the answers

<p>It facilitate the uptake of glucose into erythrocytes through passive transport.</p> Signup and view all the answers

<p>the initial velocity of substrate transport into the cell at various external substrate concentrations</p> Signup and view all the answers

<p>The outward-facing (T1) conformation of the transporter binds to the substrate, and then undergoes a conformational change to the inward-facing (T2) conformation, allowing the substrate to be released into the cell.</p> Signup and view all the answers

<p>Immediate metabolism of glucose in the cell</p> Signup and view all the answers

<p>3 mM; It represents the substrate concentration at half of the maximum velocity (½Vmax)</p> Signup and view all the answers

<ol> <li>High rate of diffusion down a concentration gradient</li> <li>Saturable transport (reaches Vmax)</li> <li>Stereospecific for D-glucose</li> </ol> Signup and view all the answers

<p>GLUT1 transports glucose into the cell as cellular glucose is immediately metabolized, preventing glucose accumulation inside.</p> Signup and view all the answers

<p>Glucose transporters in the MF superfamily are integral membrane proteins with 12 transmembrane (TM) segments. 4 (possibly 5) amphipathic α-helices form a hydrophilic channel for glucose transport, with charged/polar amino acids lining the channel.</p> Signup and view all the answers

<p>Glucose transport via the Gated Pore Mechanism in GLUT1 involves cycling between T1 and T2 conformations. In T1, the glucose-binding site is exposed on the outer membrane surface, while in T2, it is exposed on the inner surface.</p> Signup and view all the answers

<p>12 glucose transporters are encoded by the human genome, belonging to the Major Facilitator superfamily. They are commonly referred to as GLUT1 to GLUT12.</p> Signup and view all the answers

<p>GLUT1 is mainly present in erythrocytes and the Blood-Brain Barrier. It transports glucose into erythrocytes and facilitates glucose transport across the blood-brain barrier.</p> Signup and view all the answers

<p>The T1 conformation exposes the glucose-binding site on the outer membrane surface, while the T2 conformation exposes it on the inner surface.</p> Signup and view all the answers

<p>The GLUT family members (GLUT1-GLUT12) exhibit differences in tissue distribution, kinetic properties, and regulation. Each member has a distinct pattern of expression and functional characteristics.</p> Signup and view all the answers

<p>Cone-shaped structure, allowing K+ to pass through due to the constriction size.</p> Signup and view all the answers

<p>They interact with dehydrated K+, replacing interactions with H2O, optimizing for K+ ions.</p> Signup and view all the answers

<p>K+ ions move rapidly through the channel in single file, hopping between sites, and repulse each other to prevent overcrowding.</p> Signup and view all the answers

<p>It allows K+ ions to pass through while excluding smaller ions like Na+, based on size.</p> Signup and view all the answers

<p>There are 4 sites, but 2 of them are occupied by H2O molecules, leaving 2 sites for K+ ions.</p> Signup and view all the answers