Chapter 4(Factors Affecting the direction of transport) Flashcards
What is active transport? Give an example.
Transport of molecules across a membrane if it requires energy(ATP). Needs carriers to pump in and out. Calcium ATPase pumps.
What is passive transport?Based on what? Give an example.
Transport of molecules across a membrane not requiring energy. Concentration gradient. O2 simple diffusion.
What is simple diffusion?
Form of passive diffusion, movement of a molecule into or out of cell by its own thermal motion.
What is a driving force?
When a difference in energy exists across a membrane, will push molecules in one direction or another. Always higher to lower.
Three types of driving forces.
Chemical, Electrical, Electrochemical
What is meant by moving down concentration gradient?
Moving from higher to lower concentration
What is meant by moving up concentration gradient?
Moving from lower to higher concentration.
What type of driving force is concentration gradient?
Chemical driving force. Always down.
What happens to chemical driving force as concentration increases?
It increases as well.
Electrical driving forces arise how?
Due to the membrane potential( a difference in electrical potential or voltage that exists across the membranes of most cells.
What is the overall charge in the body and why?
Zero, because cations equal the amount of anions.
Are cations and anions equal in intra/extracellular fluid?
No. Intracellular fluid has slight excess of anions over cations and extracellular has excess cations over anions.
Because of the positive and negative charges are distributed unequally between inside and outside, what occurs?
Separation of charge. Excess cations and anions tend to cluster towards the cell membrane .
Greater the difference in charge between the two sides of membrane means what?
Larger membrane potential.
Is glucose affected by membrane potential? Why or why not?
No, because it has no net charge.
The magnitude of the electrical driving force on an ion depends on what?
The size of the membrane potential and the quantity of charge carried by the ion.
What is electrochemical driving force?
total force acting on the ions; combination of chemical and electrical forces.
If both forces go in the same direction, which will electrochemical go? What if they are different?
The same as the forces. Will go in the direction of the larger force if they act in different directions.
When will an ion be at equilibirum?
When the membrane potential equals the equilibrium potential for that ion.
Magnitude of chemical driving force proportional to?
Concentration gradient.
