- Created by: Sophie
- Created on: 25-10-11 11:55
- All cells have a cell membrane
- It controls what enters and exits the cell to maintain an internal balance called homeostasis
- Provides protection and support for the cell
- Structure of cell membrane = lipid bilayer
- Phosphate head is polar (water loving)
- Fatty acid chains non-polar (water fearing)
- Proteins are embedded in membrane
- Have ppores which are slectivley permeable: allows some molecules in and keeps other mollecules out.
Types of cellular transport-passive transport
- Cell doesn't use energy (e.g diffusion, facilitated diffusion, osmosis)
- Molecules move randomly
- Molecules spread out from a high concenttration to a low concentration
- Random movement of particles from high to low concentration
- Diffusion continues untill all molecules are evenly spread and equilibrium is reached. (NOTE: molecules will still move, just evenly)
Passive transport continued
- Diffusion of specific particles through transport proteins found in the membrane.
- Transport larger or charged molecules
- Diffusion of water through a partial permeable membrane.
- From high water potential to a low water potential
Types of cellular transport-active transport
- Uses energy
- movement from a low concentration to a high concentration
- Transport proteins that require energy to do work (e.g sodium/potassium pumps are important in nerve responses)
- Taking bulky material into a cell
- In-folds around the "food" particle and forms food vacuole and digests food.
- Forces material out of cell in bulk. Cell changes shape which requires energy.
Hypotonic solution, Hypertonic solution and Isoton
Hypotonic: the solution has a lower concentration of the solutes and a higher concentration of water than inside the cell. (Low solute; high water)
RESULT: Water moves from the solution to inside the cell; cell swell and bursts (cytolysis)
Hypertonic: The solution has a higher concentration of solutes and a lower concentration of water inside the cell (High solute;low water)
RESULT:Wter moves from inside the cell into solution; cell shrinks (plasmolysis)
Isotonic:The concentration of solutes in the solution is equal to the concentration of solutes inside the cell
RESULT: Water moves equally in both direction and cell remains sam size. (Dynamic equilibrium)