Passive Transport: Diffusion and Osmosis quiz #1 Flashcards
Passive Transport: Diffusion and Osmosis quiz #1
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What is the difference between simple diffusion and facilitated diffusion in passive transport across cell membranes?
Simple diffusion involves the unassisted movement of small, uncharged, non-polar molecules from high to low concentration, while facilitated diffusion requires transport proteins (channel or carrier proteins) to help larger or polar molecules cross the membrane, still moving down their concentration gradient without energy input. How do channel proteins and carrier proteins differ in their roles during facilitated diffusion?
Channel proteins provide a passageway for molecules to move across the membrane, while carrier proteins bind to the molecule and undergo a conformational change to transport it across the membrane. Describe the three types of transport proteins involved in facilitated diffusion and give an example of each.
Uniport transports one molecule at a time (e.g., GLUT1 glucose transporter), symport moves two molecules in the same direction, and antiport moves two molecules in opposite directions (e.g., sodium-calcium antiporter). What is osmosis, and how does it relate to solute concentration across a semipermeable membrane?
Osmosis is the diffusion of water across a semipermeable membrane from an area of low solute concentration (high water concentration) to high solute concentration (low water concentration). What role do aquaporins play in osmosis, and how do they facilitate water movement?
Aquaporins are channel proteins that allow rapid water transport across membranes by forming hydrogen bonds with water molecules, enabling fast movement without conformational changes. How do cells respond to hypertonic, hypotonic, and isotonic solutions in terms of water movement?
In a hypertonic solution, water leaves the cell causing it to shrink; in a hypotonic solution, water enters the cell causing it to swell; in an isotonic solution, water movement is balanced and the cell remains the same size. What is osmotic pressure and what does it indicate in the context of osmosis?
Osmotic pressure is the pressure required to stop the flow of water across a semipermeable membrane, and it is determined by the solute concentration difference across the membrane. What is the main difference between simple diffusion and facilitated diffusion in passive transport across cell membranes?
Simple diffusion allows small, uncharged, non-polar molecules to move directly across the membrane, while facilitated diffusion requires transport proteins to help larger or polar molecules cross the membrane without energy input. How do channel proteins and carrier proteins differ in their mechanisms during facilitated diffusion?
Channel proteins provide a passageway for molecules to move through the membrane, whereas carrier proteins bind to the molecule and undergo a conformational change to transport it across. What is osmosis and how does it relate to solute concentration across a semipermeable membrane?
Osmosis is the diffusion of water across a semipermeable membrane from an area of low solute concentration (high water concentration) to high solute concentration (low water concentration).
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