Where are we going with this? The information on this page should increase understanding related to this standard: Evaluate comparative models of various cell type…Evaluate eukaryotic and prokaryotic cells.
- Fluid: constantly moving
- Mosaic: multiple pieces in the membrane
In addition to the cell membrane, plant cells have cell walls that function to provide structure, support, and protection for the cell. They are made up mostly of cellulose, a polysaccharide carbohydrate.
- Channel proteins have a hollow channel which allows large, polar molecules and/or ions into or out of the cell.
- Carrier proteins provide protection for larger, charged, and/or hydrophilic molecules as they enter or exit the cell.
- is the point when the number of solutes is the same on both sides of the membrane
- is when the rate of materials going in equals the rate of materials going out.
Almost everyone can easily visualize another type of equilibrium. Not cellular, but thermal. Heat energy, like molecules in passive transport, flows from matter with high levels of energy to matter with low levels. If the temperature of our soda is too high, we can transfer some of that heat to something that is colder. Ice? Sure! Putting ice into a drink introduces matter with low levels of energy. The energy from the warm soda flows into the ice. The result is lower energy in the soda—it cools off. Eventually, equilibrium is reached with all of the ice is melted (but then the high heat energy from the room starts to flow in low heat energy of the soda).
Understanding diffusion benefits from understanding solutions, but we'll get more formally into that later on. But, previewing, think of a solution as water with stuff dissolved in it. (Like sugar dissolved in water.)
Diffusion deals with the particles (the stuff) dissolved in the water moves from where there's a lot of them to where theres not many of them.
Simple diffusion is normal diffusion, which does not require any sort of transport protein. Simple diffusion occurs when particles move through the phospholipid bilayer directly.
Facilitated diffusion is diffusion that requires the use of transport proteins. Facilitated diffusion is required for larger particles and hydrophobic molecules.
Solution: a homogeneous mixture of a solvent and a solute.
so·lu·tion: a liquid mixture in which the minor component (the solute) is uniformly distributed within the major component (the solvent).
"a solution of ammonia in water"
Solvent: a fluid into which other substances can be dissolved.Solute: a substance that is dissolved into a solvent to form a solution.
Hyper: more/aboveIso: the sameHypo: less/below
Hypertonic solution - has more solute than the cell (cell will shrink)Isotonic solution - has equal amounts of solute outside of the cell (cell will stay the same)Hypotonic solution - has less solute than the cell (cell will swell)
Hypertonic solutions have more solute outside of the cell. Water will move to where there is more solute. Water moves out of the cell.
The <stuff> is the solute… something like sugar or salt or another substance a cell needs. The solute is the particles, whatever they are.
The <liquid> is the solvent… water. Let's just leave it at that. So the solute is dissolved in the solvent to create a solution with some concentration.
The <membrane enclosed thing> is usually a cell, but the concepts apply to larger structures. Going forward, we'll limit the concept to cellular passive transport.
Concentration is a concept that describes how much solute is in a solvent: how much stuff is in a liquid. For instance, how much sugar is in the water. The less water (as compared to the other thing) the higher the concentration
Sometimes to ship products (like orange juice) the liquid is removed leaving highly concentrated product. Putting water back in can return it to its original consistency.
In diffusion, the particles move
• Solutes will move from high concentration of "particles" to low.
• The solute moves in order to even out concentrations.
In osmosis, the solvent move
• Solvents will move from low concentration of "particles" to high.
• It is conceptually okay to think of the solvent moving from there there's too much solvent to where there's not enough. However, the end result is equalization of concentration, which is a measure of solvent in solute.
• The solvent moves in order to even out concentrations.