Transport across membranes Flashcards
Cell membranes and Transport
What is the definition of diffusion?
The passive net movement of molecules from a high concentration to a low concentration.
What are the 5 factors that affect the rate of diffusion?
- Temperature
- Surface area
- Concentration gradient
- Molecule size
- Lipid solubility
What is the definition of facilitated diffusion?
A passive transport process that uses specialised proteins to help move molecules across a membrane from a high to a low concentration.
What is co-transport?
A type of facilitated diffusion by which two substances are simultaneously transported across a membrane by a carrier protein.
What is the definition of osmosis?
The net passive diffusion of water molecules across a selectively permeable membrane from a region of higher water potential to a region of lower water potential.
What is the highest possible water potential?
Pure water= 0 kpa
What is pressure potential?
Cytoplasm pushing outwards on the cell wall.
What is turgidity?
When a cell has more volume and the cytoplasm pushes on the cell wall.
What is incipient plasmolysis?
A cell that has lost enough water for the cell membrane to start being drawn away from the cell wall.
