2.1.5 - Diffusion Flashcards
Diffusion (Definition)
Diffusion is the net movement of particles from a region of higher concentration to a region of lower concentration
Diffusion
- Passive process
- It will continue until there is a concentration equilibrium between the two areas
- Diffusion happens because the particles have kinetic energy
- Movement is random and an unequal distribution of particles eventually becomes an equal distribution
Factors affecting diffusion
- Temperature
- Concentration difference
Effect of temperature on diffusion
- As you increase temperature, particles have more kinetic energy and they move more
- This increase the rate of diffusion
Effect of conc difference on diffusion
- As you increase the concentration difference, the greater the net movement of particles
- This increases the rate of diffusion
Diffusion across membranes
- Simple diffusion - Absorbed directly across the membrane
- Facilitated diffusion - Nutrients need a protein channel or carrier protein to transport them
Lipid soluble
- Steroid hormone
- Oxygen
- Carbon Dioxide
Lipid insoluble
- Glucose
- Protein
- Lipid
What are phospholipid bilayers barriers to?
- Polar molecules and ions
- Membranes contain channel proteins through which polar molecules and ions can pass
Rate of facilitated diffusion depends on:
- Temperature
- Conc gradient
- Membrane SA
- Membrane thickness
- No.of channel proteins
Active transport
Active transport is the movement of molecules or ions into or out of a cell from a region of lower concentration to a region of higher concentration
- Requires energy(supplied by ATP)
- Requires carrier proteins
How does active transport occur?
- Molecule bonds to receptor
- ATP binds to carrier proteins - ATP hydrolysed to ADP and phosphate
- Binding of phosphate to carrier protein causes the protein to change shape
- Molecule released to inside of the cell
- Phosphate molecule released from carrier protein and recombined with ADP to form ATP
- Carrier protein returns to its original shape
