Principles of Transmembrane Transport quiz #1 Flashcards
Principles of Transmembrane Transport quiz #1
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What are the main differences between passive and active transport across cell membranes?
Passive transport moves molecules from high to low concentration without energy input, either by simple diffusion or facilitated diffusion using membrane proteins. Active transport moves molecules against their concentration gradient (from low to high concentration) and requires energy, usually from ATP. How does the semipermeable nature of the cell membrane affect the movement of different types of molecules?
The semipermeable membrane allows small nonpolar molecules and some small uncharged polar molecules to pass freely, while large polar molecules and charged ions are generally excluded, enabling the cell to regulate its internal environment. What is the difference between concentration gradient, electrical potential, electrochemical potential, and membrane potential?
A concentration gradient is the difference in molecule concentration across the membrane. Electrical potential is the difference in charge across the membrane. Electrochemical potential combines both concentration and electrical differences as a driving force, while membrane potential refers to the net difference between concentration gradient and electrical potential. What are the three main classes of transmembrane proteins involved in transport, and how do they function?
Channels allow specific molecules based on size or charge to pass through. Transporters are highly selective, allowing only specific molecules that bind to them to cross. ATP-powered pumps use energy from ATP to move molecules across the membrane, often against their gradient. What property of the cell membrane allows it to regulate which molecules enter or exit the cell?
The cell membrane is semipermeable, allowing only certain molecules to cross and thus regulating the cell's internal environment. Which types of molecules can freely cross the semipermeable cell membrane, and which are generally excluded?
Small nonpolar molecules and some small uncharged polar molecules can cross freely, while large polar molecules and charged ions are generally excluded. What is the main difference between passive and active transport across cell membranes?
Passive transport moves molecules from high to low concentration without energy input, while active transport moves molecules against their gradient and requires energy, usually from ATP. How do simple diffusion and facilitated diffusion differ in passive transport?
Simple diffusion allows molecules to cross the membrane without assistance, while facilitated diffusion requires the help of membrane proteins but still does not use energy. What are the three main classes of transmembrane proteins involved in transport, and how does each function?
Channels allow specific molecules based on size or charge to pass, transporters are highly selective for specific molecules, and ATP-powered pumps use ATP to move molecules across the membrane. How do concentration gradient, electrical potential, electrochemical potential, and membrane potential differ?
Concentration gradient is the difference in molecule concentration, electrical potential is the charge difference, electrochemical potential combines both as a driving force, and membrane potential is the net difference between concentration and electrical potential.
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