2.5.3 Diffusion & Facilitated Diffusion Flashcards
1
Q
Diffusion Def
A
Net movement of molecules or ions a as result of random motion (kinetic energy) of a substance from a region of higher concentration to a lower concentration
2
Q
How can large polar molecules or ions diffuse across cell membranes?
A
- Via facilitated diffusion by transport proteins
- Channel proteins or carrier proteins
- Highly specific
3
Q
What are channel proteins?
A
- Gated proteins
- Molecules are let through WITHOUT A CHANGE IN SHAPE
- Allow exchange of ions
4
Q
What are carrier proteins?
A
- Switch between 2 shapes
- Binding sites of carrier proteins change shape
- Net diffusion of molecules or ions occurs down a concentration gradient
5
Q
Why can’t glucose diffuse through a cell membrane?
A
- Glucose molecule is too large
- And phospholipids act as a barrier
OR - Glucose molecules are insoluble in phospholipids because of polar OH- groups
6
Q
A
