BRAINCAKEMembrane Proteins
Proteins make up a large part of every membrane and carry out most of its specific jobs. They are classified by their position in the bilayer.
Intrinsic proteins (integral proteins) are embedded in the bilayer, and many span it completely, from one side to the other. Their hydrophobic amino acids lie against the fatty acid tails, and their hydrophilic amino acids face the watery surroundings.
Extrinsic proteins (peripheral proteins) sit on the inner or outer surface of the membrane, loosely attached to intrinsic proteins or phospholipid heads. They do not enter the hydrophobic core.
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Key terms in this lesson
- facilitated diffusion
- The passive movement of ions or polar molecules down their concentration gradient through a membrane via a channel or carrier protein.
- active transport
- The movement of molecules or ions across a membrane against their concentration gradient, using energy from ATP.
More in Eukaryotic Cells
- Scanning Electron Microscope
- Ultrastructure
- Membranes
- Phospholipid Bilayer
- Fluid Mosaic Model
- Eukaryotic Cells
- Protoplasm
- The Nucleus
All 30 lessons in Eukaryotic Cells · All Edexcel AS-level Biology topics