1. What is a solute? 2. What is a solvent? 3. What is diffusion and osmosis? 4. What does it mean to be active? 5. What does it mean to be selective? 6. What is a sac? 7. What is a receptor? 8. What do the prefixes aqua-, endo-, and exo- mean?

 Solution – a homogenous mixture of two or more components in which the solute (thing that is dissolved) does not settle out of the solvent.  Intracellular fluid – fluid inside the cells  Interstitial fluid – fluid outside the cell  Both fluids contain various solutes from gases, nutrients and salts

 Selective permeability – a barrier allows some substances to pass through but excludes others  Passive Transport Processes – substances are transported across the membrane without any energy input from the cell  Active Transport Processes – cell have to provide the energy to complete the transport process

 A movement of particles and molecules from an area of high concentration to areas of low concentration  Cell use simple diffusion – the unassisted diffusion of solutes through the plasma membrane. These particles have to be either 1) Small enough to pass through the pores (ions) 2) Can dissolve in the fatty portion of the membrane (fats, oxygen, carbon dioxide)

 Diffusion of water through selectively permeable membranes  In the cell, this occurs in special pores called aquaporins, which are created by proteins in the membrane

 If molecules are too large to fit through pores or cannot dissolve into the fatty portion of the membrane, they may have to move through a protein membrane channel or may have to use a carrier protein to complete their movement from high to low concentrations.

 Forcing water and solutes through a membrane.  In this case, a pressure gradient actually pushes solute containing fluid from a higher pressure to a lower pressure.

Uses ATP

 An active process in which special carrier proteins use ATP to move molecules against their concentration gradients  Examples Moving large amino acids and sugars into the cell The sodium-potassium pump – moves sodium out and potassium in

 Exocytosis – moves substances out of the cell by packaging the substances in sacs, allowing them to move to the cell membrane, where the sac fuses with the membrane and the contents of the cell are ejected.  Endocytosis – into the cell. Materials outside the cell are “captured” by part of the membrane, which surrounds the material and allows it to move into the cell in a sac.

 Phagocytosis – “cell eating”, a protective process, specific phagocytes meet up with a sac, fuse with it, and digest the contents  Pinocytosis – fluid-phase endocytosis. Allows a cell to take in fluids  Receptor-mediated endocytosis – receptors on the cell membrane target certain molecules, that once they bind to the target, endocytosis occurs to move the target into the cell