Transport Across The Membrane Flashcards
What are the 2 substances that make up the cell membrane?
Proteins and phospholipids
Which substance is involved in the transport of other substances across the membrane?
Proteins
What is the term used to describe the membrane, and why?
Selectively permeable as is allows some substances to pass but not others
What are the 2 requirements for a substance to pass the cell membrane?
They must be small and soluble
What is the definition of diffusion?
Diffusion is the movement of molecules from an area of high concentration to an area of low concentration down a concentration with out using energy, as it is a passive process
When does a concentration gradient exist?
When there is a difference in concentration between 2 areas
Name 3 useful substances diffused into cells
- Glucose
- Amino acids
- Oxygen
Name 2 waste products diffused out of the cell
- Carbon dioxide
2. Urea
What is the definition of osmosis?
Osmosis is the diffusion of water molecules from an area of high water concentration to an area of low water concentration down a concentration gradient, not requiring energy as its a passive process
If animal cells lose too much water through osmosis, they…
Shrivel & shrink
If animal cells gain too much water through osmosis, they…
Burst
If a plant cell loses too much water through osmosis…
The cell membrane peels away from the cell wall, and the cell becomes plasmolysed
If a plant cell gains too much water, it…
Becomes turgid, as the cell wall prevents the cell from bursting, instead the cell swells up
What is the definition of active transport?
Active transport is the movement of molecules and ions from an area of low concentration to an area of high concentration, against a concentration gradient, while requiring energy in the process, as it is an example of active transport
What is the sodium/potassium pump?
A form of active transport, where sodium is pumped out of the cell while potassium is pumped into the cell, against a concentration gradient
