TOPIC 2-Diffusion Flashcards
What are the two different types of diffusion?
-Simple
-Facilitated
What is diffusion?
-The net movement of particles (molecules or ions) from an area of higher concentration to an area of lower concentration
Which way will the net movement diffuse?
-To the area of lower concentration which continues until the particles are evenly distributed throughout the liquid or gas
What is the concentration gradient?
-The path from an area of higher concentration to an area of lower concentration
Is diffusion an active or passive process?
-Passive
Is any energy required for diffusion?
-No
Define simple diffusion
-When molecules diffuse directly through a cell membrane
Give an example of simple diffusion.
-Oxygen and carbon dioxide can diffuse easily through cell membranes because they are small so they can pass through spaces between the phospholipids
-They are also non-polar so which makes them soluble in lipids so they can dissolve in the hydrophobic bilayer
What are some specialised cells adapted for?
-Rapid transport across their membranes
What are the 3 factors affecting the rate of diffusion?
-Concentration gradient
-Thickness of the exchange surface
-The surface area
The 1___ the concentration gradient, the 2___ the rate of diffusion
- Higher
- Faster
What happens to the difference in concentration between the two sides of the membrane?
-Decreases until it reaches equilibrium (the concentration on both sides is equal)
-This means that diffusion slows down over time
The 1___the exchange surface, the 2___ the rate of diffusion
- Thinner
- Faster
Why is the diffusion rate faster if the exchange surface is thinner?
-The shorter the distance the particles have to travel?
The 1___ the surface area the 2___ the rate of diffusion
- Larger
- Faster
Why is it faster if there is a larger SA?
-More space for the particles to diffuse across the membrane
Why is the rate of diffusion faster if the concentration gradient is higher?
-Molecules move down the concentration gradient
Why do larger molecules diffuse very slowly?
-They cannot move through the phospholipid bilayer quickly because they are too big
Why do charged particles diffuse slowly?
-They are water-soluble and the centre of the bilayer is hydrophobic
Define facillitated diffusion?
-Large or charged particles diffuse through carrier proteins or channel proteins in the cell membrane instead
Is facilitated diffusion still moving down a concentration gradient and is it a passive process?
-Yes
What is the function of carrier proteins?
-To move large molecules across the membrane down their concentration gradient
-Different carrier proteins facilitate the diffusion of different molecules
How do carrier proteins work?
-First, a large molecule attaches to a carrier proteins in the membrane
-The protein changes shape
-This releases the molecule on the opposite side of the membrane
How do channel proteins work?
-Form pores in the membrane for charger particles to diffuse through (down their concentration gradient)
-Different channel proteins facilitate the diffusion of different charged particles
