Flashcards in Diffusion Deck (17):
What is diffusion?
-Movement of particles from a region of high to a region of low concentration.
-Passive process, doesn't require energy and will continue until an equilibrium.
What does equilibrium mean?
-Balance in concentration.
Why does diffusion happen?
-Due to particles in a gas or liquid having kinetic energy.
-Movement is random and will carry on until an equilibrium.
When is diffusion fastest and why?
-Over short distances because more frequent and successful collisions as they have most kinetic energy.
What factors affect the diffusion rate?
How does temperature affect diffusion rate?
-The higher the temperature, the higher the rate due to more kinetic energy and higher speeds.
How does concentration difference affect diffusion rate?
-The greater the difference in concentration the faster the rate of diffusion.
How does distance affect diffusion rate?
-The shorter the distance the faster the rate of diffusion.
What is simple diffusion?
-Diffusion in the absence of a barrier or membrane.
How does diffusion happen across a membrane?
-Particles pass through the phospholipid bilayer.
-Can only happen if membrane is permeable to particles for example oxygen can diffuse freely.
Why are membranes partially permeable?
-Only allows certain molecules diffuse through.
-Ions cannot pass easily because hydrophobic interior repels these.
-Polar molecules can diffuse at a slow rate.
-Small polar molecules ca diffuse much easier.
How does surface area affect rate of diffusion across a membrane?
-The larger the area of exchange surface, the higher the rate of diffusion.
How does thickness of membrane affect the rate of diffusion across a membrane?
-The thinner the exchange surface, the higher the rate of diffusion.
What is facilitated diffusion?
-Diffusion across a membrane through channel proteins.
-Passive process, down a concentration gradient and doesn't requires energy.
What particles can facilitated diffusion allow to pass?
-Polar molecules and ions.
Are membranes with protein channels permeable?