3.3 and 3.5 Diffusion, Osmosis, Active Transport and Exo/Endocytosis
Why do organisms with cell walls not burst during osmosis?
- Cell membrane pushes against cell wall. - The rigid cell wall resists due to its own structural integrity. - These opposing forces create turgidity, which keeps plants upright.
What is a hypotonic solution?
- Less dissolved particles outside of cell than inside of cell. - Hypo = less and Tonic = dissolved particles. - Water moves into cell from solution. - Cell expands (may burst).
What is a hypertonic solution?
- More dissolved particles outside the cell than inside of the cell. - Hyper = more and Tonic = dissolved particles. - Water moves out of cell into solution. - Cell shrinks.
What is a isotonic solution?
- Solute concentration of solution equal to that of cell. - No net water movement.
What happens in facilitated diffusion?
- Substance binds to membrane-spanning transport protein. - Binding alters protein conformation, exposing the other surface. - Particles move from areas of high concentration to areas of low concentration.
What happens to animal cells in osmosis?
Animal cells will expand and may burst.
What factors affect diffusion across a plasma membrane?
Diffusion directly through lipid bilayer and diffusion of hydrophilic molecules across a plasma membrane.
What happens when net diffusion stops?
Equilibrium is reached and diffusion of one compound is independent to diffusion of other compounds.
What is an example of something that takes place in facilitated diffusion?
Glucose. It binds to the transport protein and the transporter changes conformation and glucose is released into the cell.
What are the three solution types relative to the cell?
Hypertonic solution, hypotonic solution, and isotonic solution.
What does facilitated diffusion allow to diffuse?
It allows diffusion of large, membrane insoluble compounds such as sugars and amino acids. Down a concentration gradient.
What can movement of water into a cell do to the plasma membrane?
It can put pressure on the plasma membrane.
What is a property of facilitated diffusion?
It is highly selective.
What is plasma membrane permeable to?
It is permeable to water but not to solute. Water moves from dilute solution (low solute) to concentrated solution (high solute).
What does diffusion occur by?
It occurs via random kinetic movement.
What happens if you don't water a plant?
It wilts, this is called plasmolysis. If you water it, the leaves will come back up due to the reestablishment of turgidity.
What is active transport?
Movement across membrane with an energy cost, It is usually against concentration gradient (from high to low concentration).
What is passive transport?
Moving molecules into/out of the cell without energy input/
Does diffusion require energy?
No diffusion doesn't require energy.
Does facilitated diffusion require energy?
No, it is passive.
What kind of organisms do not burst in osmosis?
Organisms with a cell wall, such as plants, do not burst.
What is diffusion?
Spontaneous movement of fluid (gas or liquid) particles from an area of high concentration to an area of low concentration (down a concentration gradient).
What is osmosis?
The passive transport of water. It is the diffusion of water across a semi-permeable membrane (from high to low).
When does net diffusion stop?
When concentration on both sides is equal.
Does active transport require energy?
Yes, it requires energy to overcome the concentration and electrochemical gradient or to allow a large or charged particle to cross membrane.
Is facilitated diffusion reversible?
Yes, the molecules may enter the cell and leave the cell through the transport proverb.
