Campbell #8 Cell Membrane

Summary
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

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