Unit 5: cell membrane transport and excretory sytem Flashcards
diffusion
big idea: things spread out definition: The movement of particles down their concentration gradient.
osmosis
the diffusion of water
hypertonic
a more concentrated environment water will move out of the cell and into this environment
hypotonic
a less concentrated environment water will move out of this environment and into the cell
isotonic
an equally concentrated environment the cell will be unaffected
Why do crackers go stale?
They are hypertonic. Water moves from the air to the cracker.
Why can’t we drink sea water?
Sea water is hypertonic to our cells. We get dehydrated.
Why is soil salinity a problem?
As farmers irrigate their fields, sometimes a little salt was in the water. The water is used by the plants and evaporated into the air, but the salt stays behind and its concentration increases each season. Eventually the soil will be hypertonic and no crops will grow.
Why use saline solution instead of water?
Putting water directly into your eyes or veins would make a hypotonic environment for our cells. It does not feel comfortable. Saline solution is isotonic to our cells.
Why are cells so small?
A smaller cell has a higher surface area to volume ratio. This means it has more cell membrane (ability to feed itself) than body (need for food). Bigger cells are less able to get nutrients to all parts of the cell.
passive transport
the movement of particles in or out of the cell without using energy. Could be by diffusion, osmosis, or by facilitated diffusion
facilitated diffusion
a protein in the cell membrane acts as a channel, allowing a certain kind of molecule to diffuse in or out of the cell freely.
active transport
the movement of particles in or out of the cell using energy. Could be by protein pump or by cytosis
protein pump
A protein in the cell membrane which uses energy to push a particle in or out of the cell. The pump can be used to push the particle up its concentration gradient.
endocytosis
Large molecules and viruses can attach to receptor proteins which signal the cell membrane to enfold. The fold wraps around the large molecules and pinches off, creating a vacuole inside the cell.