11.3 Flashcards
Diffusion
A movement of particles form an area of high concentration to an area if low concentration
Concentration
A measure of how much of something there is in a given volume (g/mL)
What does a cell membrane do
Controls what does and what does not enter the cell
Selectively permable membrane
A membrane that selects what to allow across and what to block
Diffusion is the main reason that?
Main reason that particles move across a membrane
The cell chooses what to let in and what not to based on..
Electrical charge
Physical size
When does diffusion stop?
When the system reaches equilibrium
Equilibrium
The state of a system when quantities are balanced
Osmosis
The diffusion of water through a selectively permable membrane
How do u predict which way water will move across a cell membrane
Compare the concentration inside to the concentration outside
Concentration of water higher inside the cell
Water will move across the lol membrane and out of the cell
Concentration of water higher outside the cell
Water will move across the cell membrane and into the cell
What uses osmosis to destroy bacteria
Penicillin
How does penicillin work
- the penicillin causes the cell membrane of the bacteria to become weaker
- there is a higher concentration of water outside the bacteria than there is inside
- water will diffuse into the bacteria because of osmosis
- the bacteria swells Intill it bursts and dies
How can diffusion/osmosis be forced backwards
Normally, water will diffuse from an area of high concentration to an area of low concentration
But, by increasing pressure on the lower concentration side, water is forced over to the higher conentration side
By insuring the membrane selectively allows water across, but nothing else, the water that results in the higher concentration/lower pressure side is purified
