Name ____________________________________ Date ____________ Period _____
CELL MEMBRANE
Raven Ch. 6
Big Idea 2: BIOLOGICAL SYSTEMS UTILIZE FREE ENERGY AND MOLECULAR BUILDING
BLOCKS TO GROW, TO REPRODUCE AND TO MAINTAIN HOMEOSTASIS.
Essential Knowledge:
 Cell membranes are selectively permeable due to their structure.
 Growth and dynamic homeostasis are maintained by the constant movement of molecules across membranes.
 Eukaryotic cells maintain internal membranes that partition the cell into specialized regions.


All biological systems from cells and organisms to populations, communities and ecosystems are
affected by complex biotic and abiotic interactions involving exchange of matter and free energy.
Homeostatic mechanisms reflect both common ancestry and divergence due to adaptation in different
environments.
The Cell Membrane
Structure:
______________________
 Phosphate head
 ___________________________
 Fatty acid tails
 ___________________________
 Arranged as a bilayer
Cell membrane defines cell
 Cell membrane separates living cell from aqueous environment
 thin barrier = ______________
 Controls traffic _____ & _____ of the cell
 allows ____________ substances to cross more easily than others
 hydrophobic (nonpolar) vs. hydrophilic (polar)
What materials are/are not able to easily move through the membrane? ____________________________
__________________________________________________________________________________________
Cell membrane is more than lipids…

______________________ proteins embedded in phospholipid bilayer
 create semi-permeable ______________________
1
Permeability to polar molecules?
 Membrane becomes semi-permeable via ______________________________
 ____________________ channels allow ____________________ material across cell membrane
Why are proteins the perfect molecule to build structures in the cell membrane? _____________________
__________________________________________________________________________________________
Classes of amino acids:
___________________________________ or ___________________________________
Proteins domains anchor molecule
 Within membrane
 ________________ amino acids
 ________________
 anchors protein
into membrane
 On outer surfaces of membrane in fluid
 ________________ amino acids
 ________________
 extend into extracellular fluid & into cytosol
Examples:
____________________________________
____________________________________
Conformational change = ___________________________________________________________
Membrane Proteins
 Proteins determine membrane’s specific functions
 cell membrane & organelle membranes each have unique collections of proteins
 Classes of membrane proteins:
 _________________________ proteins
 loosely bound to ________________________ of membrane
 ex: cell surface identity marker (antigens)
 _________________________ proteins
 penetrate lipid bilayer, usually ____________________________ membrane
 transmembrane protein
 ex: transport proteins
 channels, permeases (pumps)
2
3