Campbell #8 Cell Membrane
Concept #1 Cellular membranes are fluid mosaics of lipids and proteins
- In the membrane,amphipathic proteins are embedded in the phospholipid bilayer.
- Integral proteins are embedded in the lipid bilayer; peripheral proteins are attached to the membrane surface.
Concept #2 Membrane structure results in selective permeability
- Exchanging molecules and ions with its surrounding are controlled by the selective permeability of plasma membrane.
Concept #3 Passive transport is diffusion of a substance across a membrane (no energy investment)
- Diffusion is the spontaneous process of a substance down its concentration gradient.
- Passive transport — Facilitated diffusion, a transport protein channel lets water or a solute across a membrane down its concentration gradient.
Concept #4 Active transport uses energy to move solutes against their gradients
Concept #5 Bulk transport across the plasma membrane occurs by exocytosis and endocytosis