AP BIO cell transportation Flashcards
passive transport
Diffusion of a substance across a membrane with no energy investment
Simple Diffusion
-The tendency for molecules to spread out evenly into the available space
-Molecules move from high to low concentration
-No energy or protein assistance needed
Facilitated Diffusion
Transport proteins speed the passive movement of molecules across the plasma membrane
Osmosis
-Diffusion of free water across a selectively permeable membrane
-Water moves towards higher solute concentration until the solute concentration is equal on both sides
Transport Protein
-Provide passages that allow a specific molecule or ion to cross the membrane
(Specifically hydrophilic substances)
-Channel Proteins
(Hydrophilic channel that certain molecules or ions can use as a tunnel)
-Aquaporins
(Facilitate the passage of water)
Carrier Protein
Binds to molecules and changes shape with allows the substances to follow through
Active Transport
- Moves substances against their concentration gradients, usually requires energy as ATP
- Allows cells to maintain concentration gradients that differ from their surroundings
(Ex: sodium-potassium pump)
COTRANSPORT
When active transport of a solute indirectly drives transport of other solutes
BULK TRANSPORT
Transports large molecules via vesicles
ATP
-Adenosine triphosphate
-Composed of a ribose (sugar), adenine (nitrogenous base), and three phosphate groups
-Energy
-Used to make RNA
Sodium-Potassium Pump
-A carrier protein that uses ATP to actively transport sodium ions out of a cell and potassium ions into the cell
Steps of a Sodium-Potassium Pump
-Three sodium ions inside the cell bind to the pump protein
-The pump uses energy from ATP to change its shape
-The pump releases three sodium ions outside the cell
-Two potassium ions from outside the cell bind to the pump
-The pump returns to its original shape, releasing the two potassium ions in the cell
Tonicity
The ability of a surrounding solution to cause a cell to gain or lose water
Hypertonic
Solute concentration is greater than that inside the cell; cell loses water
Hypotonic
Solute concentration is less than that inside the cell; cell gains water
Isotonic
When the concentration of two solutions is the same, no net water movement
Electrogenic Pump
-Transport protein that generates voltage across a membrane
Animals:
Sodium potassium pump
Plants, Fungi, Bacteria:
Proton pump
Concentration Gradient (down vs. against)
-Difference in the concentration of a substance from one location to another
-Down:
From more to less concentrated
No energy is needed
-Against:
Requires work and energy
Endocytosis
Cell takes in molecules and particulate matter by forming new vesicles from the plasma membrane
Pinocytosis
- “Cellular Drinking”
- A type of endocytosis in which the cell ingests extracellular fluid and its dissolved solutes
- Used for liquid
Small Vesicles
Receptor Mediated
Receptor proteins on the cell membrane are used to capture specific target molecules and form a coated vesicle
Phagocytosis
“Cellular Eating”
Used for solid materials
Large vesicles
Exocytosis
- Transport vesicles migrate to the membrane, fuse with it, and release their contents
- Reverse of endocytosis
- Secretory cells use exocytosis to export products
