4.2 - Diffusion Flashcards
The process of simple diffusion The process of facilitated diffusion How different factors affect the rate of diffusion (20 cards)
What is diffusion?
Net movement of particles from high to low concentration
What is a concentration gradient?
Difference in concentration between two areas
What is equilibrium in diffusion?
Even distribution of particles
Is diffusion active or passive?
Passive
What are the two types of diffusion?
Simple and facilitated
What is simple diffusion?
Molecules diffusing directly across cell membranes
What type of molecules use simple diffusion?
Small and non-polar
What is facilitated diffusion?
Large or polar molecules crossing cell membranes involving Carrier/Channel proteins
What are the two types of proteins involved in facilitated diffusion?
Carrier and channel proteins
Are carrier and channel proteins specific or non-specific?
Highly specific
What do carrier proteins transport?
Mainly large molecules
How do carrier proteins work?
3 steps
- A large molecule attaches to a carrier protein.
- This causes the carrier protein to change shape.
- The carrier protein releases the molecule on the opposite side of the membrane.
What do channel proteins transport?
Mainly ions
How do channel proteins work?
Form pores in the cell membrane, which ions can travel through.
What factors affect the rate of diffusion?
atleast 3 things
Temperature - At higher temperatures, particles have more kinetic energy and diffuse faster.
Concentration gradient - The steeper the concentration gradient, the faster the rate of diffusion.
Thickness of membrane - The particles travel shorter distances through thin exchange surfaces, so diffuse faster.
Surface area - Larger surface areas mean more particles can cross the membrane at once, making diffusion faster.
Number of carrier or channel proteins - The more of these proteins, the faster the rate of facilitated diffusion.
How does temperature affect diffusion?
particles have more kinetic energy and diffuse faster
How does concentration gradient affect diffusion?
Steeper gradient = the faster rate of diffusion
How does membrane thickness affect diffusion?
Thinner membrane = diffuse faster (have to travel shorter distance)
How does surface area affect diffusion?
Larger surface area = diffusion faster (more particles cross at once)
How does the number of carrier/channel proteins affect diffusion?
More proteins = faster rate of facilitated diffusion.
