Cell Memebrane Functions/osmosis/transports Flashcards
(26 cards)
What is passive transport
A molecule passing through the cell membrane with no use of ATP energy
What is diffusion
The simplest form of passive transport
Which direction will molecules move: higher to lower
Or
Lower to higher
Higher to lower
What factors determine how easy it will be for a molecule to move across the cell membrane
Size and type of the molecule
What is osmosis
The process by which water diffuses across a membrane
Will water move to or away from a high solute concentration?
Water will move to the area with a high solute concentration
(Because the area will have a lower concentration of water)
Hypotonic solution
Lower concentration of solute molecules, so more water. Meaning water will want to move away from a hypotonic area.
Hypertonic Solution
Higher concentration of solute molecules, less water.
Water will want to move to this area
Isotonic solution
Equal concentration of solute molecules
Water will move, or diffuse, to both areas equally
What two things help cells deal with osmosis
Contractile vacuole - collects excess water and pumps it out of the cell (in freshwater unicellular organisms)
Cell walls - solid enough to keep the cell from bursting (in plants)
What happens if cells can’t deal with osmosis
Plasmolysis - the cell shrivels because of loss of turgor pressure
Cytolysis - the cell bursts
What is the osmotic condition of a plant that plant cells require
Hypotonic
In what osmotic condition will a plant lose turgor pressure
Hypertonic
How is facilitated diffusion carried out
Uses channel proteins to move molecules through the cell membrane
(No energy input needed)
What are ion channels
Small passageways across the cell membrane
What will ion channel gates respond to by opening or closing
Stretching of the cell membrane
Electrical signals
Chemicals in the cytosol or external environment
Why do ions need the ion channels
Ions aren’t soluble in lipids, so they can cross the membrane
What is active transport
Moves molecules up the their concentration gradient, from lower to higher
(Required energy)
What are the carrier proteins used in active transport called?
Pumps
(More specifically sodium-potassium pumps)
How do the sodium-potassium pumps work?
They move three sodium ions out of the cell for every two potassium ions it moves into the cell
(ATP supplies the energy for this process)
Generally, what are endocytosis and exocytosis used for?
To transport macromolecules, food particles and large quantities of small molecules through the cell membrane inside vesicles
What are vesicles?
Small vacuoles
What is Exocytosis
Vesicles made by the cell fuse with the cell membrane, releasing their contents outside the cell
What is endocytosis
The cell membrane folds around something and forms a pouch, the pouch then pinches off and becomes a vesicle in the cytoplasm
