Lab Week 2 Flashcards
Cells are…?
Semipermeable
What is selectively permeable?
The cell decides what material will be allowed to cross the cell membrane and what cannot
Can cells be both semipermeable and selectively permeable?
Yes
What is dialysis tubing?
Stimulated cell membrane
Semipermeable
What is a phospholipid bilayer?
Basic molecular structure of all cell membranes
What limits what will move past the cell membrane and why?
1) size
- cell membranes have tiny holes, material that can go through are very tiny and big material cannot
- if big things want to go through they need special mechanisms
2) charge
- anything with a charge (ions) would find it difficult unless they have a special mechanism
Movement of materials through cell membranes follow what law?
Law of diffusion
What is diffusion?
Molecules and atoms that go from areas with a lot of them to areas with none or very little of them
Happens naturally
What does diffusion described as?
Concentration gradient
- goes from high to low
What is an even distribution of material?
Equilibrium (no more movement if this takes place)
What is osmosis?
An example of diffusion when water molecules going down their concentration gradient through semipermeable membranes
What are two conditions needed for osmosis?
1) water is diffusing
2) must be passing through semipermeable membrane
What is passive transport?
Osmosis and diffusion do this
When no energy is needed and it goes naturally high to low (the concentration gradient goes down)
What is active transport?
When cells move things across the membrane the opposite way, from low to high, needing energy because it is against the concentration gradient
What is diffusion and osmosis interested in?
Diffusion- solute
Osmosis- solvent