Chapter 3.2 Flashcards
Cell Transport
No energy required
Passive membrane transport
Difference in concentration when comparing two solutions
Concentration gradient
ATP required
Moving against concentration gradient
Active membrane transport
Diffusion
Filtration
Two types of Passive Transport
Moving from areas to high concentration to low concentration
Diffusion
Concentration - Larger difference = faster
Molecular size - Smaller = faster
Temperature - High = faster
Factors that influence diffusion:
Nonpolar, lipid-soluble substances diffusion directly through phospholipid bilayer
Ex. oxygen, carbon dioxide, fat-soluble vitamins
Simple diffusion
Passive transport of substance across the cell membrane with the aid of either protein carriers or protein channels
Molecules that are too big to pass on their own
Facilitated diffusion
Formed by transmembrane proteins, have aqueous-filled cores
1. Leakage - always open
2. Gated - controlled by chemical or electrical signal
Channels
Transmembrane integral proteins that transport specific polar molecules that are too large for membrane channels
Protein will change its shape to let things in and out
Carriers
All carriers are bound to molecules and are busy
Saturated
Diffusion of solvent, such as water, across a selectively permeable membrane
Occurs when concentration is different on the two sides of a membrane
Movement from high free water concentration to low free water concentration
Osmosis
Water specific channel
Aquaporin
Measure of total concentration of solute particles in a solution
Osmolarity
Ability of a solution to change the shape or the tone of cells by altering the cell’s internal water volume
Tono = tension
Tonicity
Same solute concentration as inside the cell
No net loss or gain of water
Cells maintain their normal shape
Isotonic solution
Higher concentration of solutes than inside of the cell
Water flows out of cell
Cell shrinks and shrivels (crenation)
Hypertonic solution
Lower solute concentration than inside of cell
Water flows into the cell
Can swells and can burst (lysing)
Hypotonic solution
Red blood cell lysis (bursting)
Hemolysis
Can substances that are too large to pass through the membrane move passivley?
No
Moves solute against the gradient
Uses solute pumps
1. Primary active transport
2. Second active transport
Active transport
Carrier proteins that bind specifically and reversibly with substance being moved
Used in active transport
Solute pumps
Hydrolysis of ATP occurs (phosphorylation), and energy is created directly from the process in pumps
Primary active transport
Transport one substance into cell while transporting a different substance out of cell
Opposite directions
Antiporters
Transport two different substances in the same direction
Symporters
Depends on ion gradient that was created by primary active transport
Energy stored in gradients is used to indirectly to drive transport of other solutes
Secondary active transport (cotransport)
Transport of large particles, macromolecules, and fluids across membrane in membranous sacs called vesicles
4 types: Endocytosis, exocytosis, transcytosis, vesicular trafficking
Vesicular transport
Endocytosis
Transport into cell
Exocytosis
Transport out of cell
Transcytosis
Transport into, across, and then out of cell
Vesicular trafficking
Transport from one area of the cell to another
Cell engulfs a large particle by forming projecting pseudopods around it and closing it with membranous sac
Phagocytosis
Cell “gulps” a drop of extracellular fluid containing solutes into tiny vesicles
Drop = small = pino
Pinocytosis
Extracellular substances bind to specific receptor proteins, enabling the cell to ingest and concentrate specific substances (ligands) in protein coated vesicles
Receptor-mediated endocytosis
