1. Cellular Transport

2. Diffusion Maintaining homeostasis
Cell membranes help organisms maintain homeostasis by controlling what substances may enter or leave cells.
Passive Transport- substances can cross the cell membrane without any input of energy

3. Diffusion Molecular motion
Molecules are in constant motion because they have kinetic energy (brownian motion)
Molecular motion is random
Molecules tend to move from areas where they are more concentrated to areas where they are less concentrated

4. Diffusion- movement of molecules from area of higher concentration to area of lower concentration
Concentration gradient- difference in the concentration of molecules across a distance
So, molecules tend to move “down” their concentration gradient
Diffusion will eventually cause the molecules to be in equilibrium
Equilibrium- concentration of molecules will be the same throughout the space the molecules occupy

5. Diffusion
Simple diffusion- diffusion of substances across the cell membrane without the help of membrane proteins
Facilitated diffusion- the movememt of molecules across the cell membrane is assissted by specific proteins in the membrane
Used to move large molecules, polar molecules, ions
Carrier proteins- used in facilitated diffusion

6. Osmosis
Osmosis- the process by which water moleucles diffuse across a cell membrane from high to low concentration
Form of passive transport (does not requir energy)

7. Direction of Osmosis
Depends on relative concentration of solutes on the two sides of the membrane
Hypotonic- describes solution with solute concentration lower than concentration inside cell (water diffuses in)
Hypertonic- describes solution with solute concentration higher than concentration in cell (water diffuses out)
Isotonic- describes solution with solute concentration equal to concentration in cell (water diffuses in and out at same rate)

8. How osmosis affects living cells

10. Active transport
Active transport- when cells move materials from area of lower concentration to an area of higher concentration, “against” the concentration gradient (requires energy, ATP)

11. Cell membrane pumps
Carrier proteins – “pumps”- moving from low to high concentration
Sodium-potassium pump- transports Na+ ions and K+ ions up their concentration gradient
Helps create electrical impulses that are important in animal cells (nerve cells)

12. Movement in vesicles
Endocytosis- process by which cells ingest external fluid, macromolecules, and large particles, including other cells by forming a vesicle
Pinocytosis- involves transport of solutes or fluids
Phagocytosis- movement of large particles or cells

13. Exocytosis- process by which a substance is released from the cell through a vesicle