diffusion Flashcards
define passive transport
a type of transport that doesnt use ATP from respiration, and relies on the random movement of particles.
what are the two types of diffusion ( which are also passive transport)?
- simple diffusion.
- Facillitated diffusion.
descsribe simple diffusion
This is when particles move down a concentration gradient, until all the particles are spread out evenly, between the inside, and the outside of the cell.
describe facilitated diffusion.
STEP 1: A chemical messenger, binds to the binding site on the transport protein, and in response, the transport proteins shape changes, causing it to open, and allowing the desired type of particle to pass through.
STEP 2: Particles move through transport protein, VIA facillitated diffusion, until all particles are evenly spread out.
define a transport protein.
A protein that spans the membranes of the cell or organelle, and opens or closes to allow specific particles to pass through.
explain what a concentration gradient is.
difference in the concentration of particles, between two areas, is called a concentration gradient.
Explain why polar, and hydrophilic particles cant pass through the membrane VIA simple diffusion?
Because the fatty acid tails of the phsopholipids, are non- polar, and hydrophobic. And they only allow like particles to pass through.
Exlplain why charged particles cant pass through the membrane VIA simple diffusion.
Because the fatty acid tails of the phospholipids, are uncharged, which means they only allow uncharged particles to pass through.
Explain how unsaturated fatty acids, allow molecules to pass through the membrane.
They have one or more double bonds between their carbon atoms.
These cause bends in their chains, which means that they now cant be tightly packed together.
As a result phospholipids are able to form small gaps in between membranes, giving them space to tilt side to side.
The molecules can then pass through these small gaps.
explain why large particles cant pass through the membrane VIA simple diffusion.
The gaps in the membrane are tiny, and therefore only allow tiny molecules to pass through.
state all the 4 types of particles that cant pass through the membrane, VIA simple diffusion
Polar, Hydrophilic, Charged, and Large particles.
Explain what is meant by the term hydrophobic.
substance that doesnt dissolve in water.
Explain what is meant by the term hydrophilic.
Substance that dissolves in water.
explain how a concentration gradient, influences the rate of diffusion.
The steeper the concentration gradient, the faster the rate of diffusion. And VICE-VERSA.
Same goes for osmosis ( the higher the differnece in water potential, the faster the rate of osmosis)
Explain how giving the shortest possible diffusion pathway, influences the rate of diffusion.
to maximise the rate of diffusion, cells give the shortest possible diffusion pathway.
