Cell transport mechanisms Flashcards
What is passive transport?
Transport that requires no energy from the cell and takes place due to chemical, concentration or electro-chemical gradients
What is active transport?
The movement of substances into or out of the cell using ATP
What is diffusion?
The movemnet of particles in a liquid or gas down a concentration gradient from an area of high concentration to an area of low concentration
What is facilitated diffusion?
Diffusion that takes place through carrier proteins or protein channels
What is osmosis?
A form of diffusion that involves the movement of solvent molocules down a concentration gradient through a partially permeable membrane
What is endocytosis?
The movement of large molocules into cells through vesicle formation
What is exocytosis?
The movement of large molocules out of a cell by vesicle formation
Why does diffusion occur?
Molocules move about randomally until they are evenly spread
What is an isotonic solution?
A solution where the osmotic concentration of the solutes is the same as that in the cell
What is a hypotonic solution?
A solution where the osmotic concentration of solutes is lower than the cell
What is a hypertonic solution?
A solution where the osmotic concentration of solutes is higher than the cell
How does the cell wall of plants prevent them from bursting?
If the surrounding fluid is hypotonic to the cell, water floods in and the cytoplasm presses on the cell wall and creates hydrostatic pressure. The cell wall keeps it from bursting
What is pressure potential?
The inward pressure excerted by the cell wall in plant cells that cancels out the tendency for water to move into the cell
What is turgor?
Where the cell is ridged due to being full with water
What happens if the fluid surrounding the plant cell is hypotonic?
Water rushes in and causes the cytoplasm to press against the cell wall until the pressure cancels each other out
What happens if the fluid surrounding the plant cell is hypertonic?
Water moves out of the cell by osmosis and the membrane begins to pull away from the cell wall
What is incipient plasmolysis?
Where water moves out of the cell by osmosis due to being in a hypertonic solution and the membrane moves away from the cell wall as the protoplasm shrinks
What is plasmolysis?
Where so much water leaves a plant cell that the cell membrane pulls away from the cell wall
What is water potential?
How likely water is to move out of a solution by osmosis
What substance has the highest water potential?
Water (0)
What is turgor pressure?
A measure of the inward pressure excerted by the cell wall that oposes entry of water by osmosis
What is osmotic potential?
The potential of a solution to cause water to move into a cell
How can you work out water potential?
Turgor pressure + osmotic potential
What happens when turgor pressure and osmotic potential are equal?
The cell is at full turgor and water potential is 0
What are carrier proteins?
Proteins that move substances through the membrane in active transport
What is phagocytosis?
The active process where a cell engulfs something and encloses it in a vesicle
