Cell Membrane Honors Biology Cell Size Most cells
Cell Membrane Honors Biology
Cell Size § Most cells are very small. § Why don’t we have huge cells? § What’s the limiting factor? Honors Biology
Cell Size • Smaller IS better! • Cells want a HIGH surface to volume ratio. Honors Biology
Membrane Overview § Cell membrane separates living cell from nonliving surroundings u thin barrier § Controls traffic in & out of the cell u u selectively permeable allows some substances to cross more easily than others § Made of phospholipids, proteins & other macromolecules Honors Biology
Cell Membrane’s A. K. A. ’s § The cell membrane has a lot of names! u Plasma membrane u Phospholipid Bilayer u Cytoplasmic Membrane Honors Biology
Phosphate Phospholipids § Fatty acid tails u Nonpolar & hydrophobic § Phosphate group head u Fatty acid Polar & hydrophilic § Arranged as a bilayer Aaaah, one of those structure–function examples Honors Biology
Phospholipid bilayer polar hydrophilic heads nonpolar hydrophobic tails polar hydrophilic heads Honors Biology
Membrane is a collage of proteins & other molecules embedded in the fluid matrix of the lipid bilayer Marker Protein Extracellular fluid Phospholipids Cholesterol Transport Protein Honors Biology Cytoplasm Receptor Proteins Filaments of cytoskeleton
Cell Membrane Proteins 1. Transport Proteins - allow molecules to cross through the membrane 2. Receptor Protein - Transfer information from one side to the other 3. Marker Protein - Identification for the cell Honors Biology
Marker Protein Honors Biology Receptor Protein Transport Protien
Bilayer Characteristics § Two important characteristics 1) 2) Selectively Permeable - regulates the molecules that enter and leave, thereby helping to maintain homeostasis Has Fluidity - Flexible, able to move, and to change cell shape (due to lipids) § Fluid Mosaic Model! Honors Biology
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