Name ____________________________________ Date ____________ Period _____

CELL MEMBRANERaven 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 ______________________

Permeability to polar molecules?1

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)

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