ch 6 - movement across membranes Flashcards
What is the difference between active and passive transport across membrane?
Active transport requires energy for the movement of molecules whereas passive transport does not require energy for the movement of molecules
What are the different types of passive transport?
Diffusion, facilitated diffusion, and osmosis
What is facilitated diffusion?
Movement through interior of transport proteins
- Down concentration gradient
- No energy required
- Involves channel or carrier proteins
What are the characteristics of passive diffusion?
Follows a concentration gradient
Channel vs carrier proteins
Channel proteins provide a pore for substances to move across the membrane via facilitated diffusion and carrier proteins bind to the substances they transport across the membrane via facilitated diffusion
What characterizes all active transports?
What are ion channels?
Channel proteins that transport ions
What is the mechanism of sodium potassium pump? Why does it require energy?
The sodium-potassium pump carries out a form of active transport—that is, its pumping of ions against their gradients requires the addition of energy from an outside source. That source is adenosine triphosphate (ATP), the principal energy-carrying molecule of the cell
What are electrogenic pumps? How do they create electrochemical gradient?
Transport proteins that generate voltage
across membrane (membrane potential)
- In animals: NaK ATPase
- In plants, bacteria, and fungi: proton pumps
By using ion channels to pass ions from one side of the cell membrane to the other
What is voltage?
Electrical potential energy- like a battery
What is the purpose of the concentration of the gradient?
Provides the energy (entropic energy) that drives the net movement of molecules from one side of the membrane to the other
What is cotransport?
A carrier protein that allows the transport of two different species (a solute and an ion) from one side of the membrane to the other at the same time
How do symport and antiport differ?
Symport – substances bind to same transport protein on same side of cell
eg: Sucrose-H+ cotransporter
Antiport – substances bind on opposite sides of the membrane eg: –Na+ moves in, is coupled with outward movement of Ca++ or H+
What is the role of lipids in the formation of the first cells?
