4.2) Diffusion Flashcards
What is diffusion?
The net movement of molecules or ions from a region where they are more highly concentrated to one where their concentration is lower until evenly distributed.
What type of transport is diffusion classified as?
Passive transport.
What does ‘passive’ mean in the context of diffusion?
Energy comes from the natural, inbuilt motion of particles, rather than from some external source such as ATP.
What affects the rate of diffusion?
Concentration differences.
True or False: All particles are constantly in motion due to kinetic energy.
True.
What types of molecules can easily diffuse across cell membranes?
Small, non-polar molecules such as oxygen and carbon dioxide.
What is facilitated diffusion?
A passive process that relies on transmembrane channels and carriers to help charged ions and polar molecules move across the membrane.
What are the two types of proteins involved in facilitated diffusion?
- Protein channels
- Carrier proteins
Fill in the blank: Facilitated diffusion occurs down a _______.
[concentration gradient]
What is the primary reason charged ions and polar molecules do not diffuse easily across membranes?
The hydrophobic nature of the fatty-acid tails of the phospholipids in the membrane.
True or False: Facilitated diffusion requires an external input of ATP.
False.