Passive Transport Flashcards
What is passive transport?
Passive transport is the movement of substances from a high to low concentration, it does not require energy (in the form of ATP) in order to move substances in and out of the cell.
What is diffusion?
Diffusion is simple movement from regions of high concentration to low concentration.
What is osmosis?
The movement of water across a semi-permeable membrane from an area of high concentration to an area of low concentration.
What is facilitated diffusion?
When protein transporters assist in diffusion.
What molecules can diffuse directly through the lipid bilayers?
Lipid soluble molecules and very small molecules such as oxygen and carbon dioxide.
Water and other slightly polar molecules diffuse through what?
Through hydrophillic channels in channel proteins.
The steeper the concentration gradient…
the faster the rate of diffusion.
How is movement generated in diffusion?
By the random movement of particles.
What is tonicity?
The ability of an extracellular solution to make water move into or out of a cell by osmosis.
What is a hypotonic solution?
The extracellular space contains a lower concentration of solute than the inside of the cell.
More free water outside the cell than inside
Free water will move from the extracellular space to the intracellular space in order to reach equilibrium. (water moves into the cell)
What is a hypertonic solution?
The extracellular space contains a higher concentration of solutes than the inside of the cell.
More free water inside the cell than outside.
Free water will move from the intracellular space to the extracellular space in order to reach equilibrium (water will move out of the cell).
What is an isotonic solution?
The total concentration of solute and free water on both sides of the cell is equal.
There is no water movement in or out of the cell.
If too much water moves into the cell…
Cell will lyse (will burst) in a hypotonic solution.
If too much water moves out of the cell…
Cell will shrivel in a hypertonic solution.
