3B: Passive Transport Flashcards
What are the types of passive transport?
Simple Diffusion
Facilitated Diffusion
Osmosis
What is osmosis?
The diffusion and movement of water across a selectively permeable membrane. The solute impacts the flow of the water (which direction). Low solute concentration to high solute concentration. Higher free water molecules to lower water molecules.
What are the osmosis tonicities?
Hypertonic solutions: water being moved out of cell into hypotonic solution.
Hypotonic solutions: water being moved into cell.
Isotonic solutions: equal concentration of solutes to another solution. same amount of water being removed and added to the cell (balanced, state equilibrium).
What is diffusion?
Molecules disperse until they’re evenly distributed in the available space.
What is facilitated diffusion?
When larger, charged, hydrophilic molecules cannot easily pass through the phospholipid bilayer, they use the proteins. These include glucose, ions, amino acids).
What are the types of proteins used in facilitated diffusion?
Channel proteins: Form a pore in the hydrophobic interior so water soluble molecules can pass through (salt, sugar)
Carrier proteins: Binds to the substance trying to pass through and pushes it down, so it can reach the intercellular environment.
What happens with hypotonic solutions?
When water enters the cell, there may be too much, and the cell could potentially lyse. However, this would not happen in plant cells because of the presence of a cell wall. High concentration of water outside the cell, which will move in. Having a lower solute concentration relative to another solution.
Which molecules can freely pass the phospholipid bilayer without the help of any proteins?
Small, uncharged, hydrophobic molecules, such as oxygen and carbon dioxide. Lipid-soluble molecules.
What is the direction of travel in diffusion?
High concentration to low concentration. (Down concentration gradient - out to in)
What is the direction of travel in facilitated diffusion?
High concentration to low concentration. (Down concentration gradient).
What happens when water leaves the cell?
The cell becomes flaccid and shrivels up.
What happens when water leaves the cell?
The cell becomes flaccid and shrivels up.
What is simple diffusion?
When small, uncharged, non-polar molecules easily go through the holes in the phospholipid bilayer. The substance is moving from an area of high concentration of that molecule to an area of low concentration of that molecule.
What is concentration gradient?
The difference in concentration on two sides of the membrane. If the oxygen concentration inside the cell is very very low, but outside it’s very very high, it will be quicker.
What does high osmolarity mean?
It is a hypertonic solution (higher concentration of solutes relative to another solution)
