Cellular Transport Notes Two Types of Transport Active

Two Types of Transport Active: Requires energy, usually in the form of ATP n

Continued… Simplest type of passive transport: DIFFUSION n Diffusion: movement of molecules from an

Osmosis: Diffusion of Water n Three situations: n Hypotonic: Solution outside the cell has

Continued… n Isotonic: Solution outside the cell has equal amounts of molecules and water;

What happens in each case? Hypotonic: n n Plant: turgid pressure due to the

Another diffusion: FACILITATED DIFFUSION Specific to particular molecules Involves larger molecules such as sugars

ACTIVE TRANSPORT Does NOT coincide with gradient; instead works in favor of the cell’s

Continued… n Sodium-Potassium Pump n n n Moves Sodium out Moves Potassium In Helps

Two other options for getting materials in/out of the cell n Endocytosis: “Eating it”

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Cellular Transport Notes

Two Types of Transport Active: Requires energy, usually in the form of ATP n Passive: Does not require energy, works with natural gradient n n Most important organelle involved = CELL MEMBRANE

Continued… Simplest type of passive transport: DIFFUSION n Diffusion: movement of molecules from an area of higher concentration to an area of lower concentration n Eventually equilibrium is reached when the concentration of molecules is uniformed throughout the space occupied n

Osmosis: Diffusion of Water n Three situations: n Hypotonic: Solution outside the cell has less molecules than water and water goes into the cell n Hypertonic: Solution outside the cell has more molecules than water and water leaves the cell

Continued… n Isotonic: Solution outside the cell has equal amounts of molecules and water; equilibrium has been reached

What happens in each case? Hypotonic: n n Plant: turgid pressure due to the cell wall Animal: cytolysis: bursting of the cell Hypertonic: n n Plant: wilts Animal: shrinks

Another diffusion: FACILITATED DIFFUSION Specific to particular molecules Involves larger molecules such as sugars and proteins Molecules travel through specific channels (tunnels) in the cell membrane Passive transport because no energy is used

ACTIVE TRANSPORT Does NOT coincide with gradient; instead works in favor of the cell’s needs n REQUIRES energy because often going against gradient n

Continued… n Sodium-Potassium Pump n n n Moves Sodium out Moves Potassium In Helps move amino acids and sugars in as well because they are partner molecules Helps keep your nerve impulses functioning 1/3 of your cell’s energy is spent on this pump Proton Pump n n Accumulate H+ ions on specific side of the membrane Required to convert food energy into chemical energy and vice versa n Important part of photosynthesis and cellular respiration

Diffusion of Water

Two other options for getting materials in/out of the cell n Endocytosis: “Eating it” n n Materials are engulfed by the membrane, a pouch is formed and released into the cell Exocytosis: “Spitting it out” n n Reverse of Endocytosis A pouch is made using the membrane and then released outside the cell

Endocytosis/Exocytosis