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Ch. 3 Part 1. The Cell. Vocabulary. Cytology – the study of cells Cell – the most basic, living functional unit found in the body Cell membrane Also called plasma membrane and plasmalemma. 3 Main Components of a Cell. Plasma membrane A selective permeable barrier
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Ch. 3 Part 1 The Cell
Vocabulary • Cytology – the study of cells • Cell – the most basic, living functional unit found in the body • Cell membrane • Also called plasma membrane and plasmalemma
3 Main Components of a Cell • Plasma membrane • A selective permeable barrier • Divides the extracellular fluid (ECF) from the cell’s structures • Cytoplasm • Everything between the plasma membrane and nucleus • Contains cytosol – thick intracellular fluid (ICF) • Contains organelles • Organelles • “organs of the cell” • Organized structures, specific shape, specific function
The Cell Membrane • Barrier between inside of cell and outside of cell • Constructed of • Lipid bilayer • Proteins • “sea of lipids with floating protein icebergs”
The Cell Membrane • Lipid bilayer • Phospholipids • Line up in 2 parallel rows • Constantly moving and changing places • Called the “Fluid Mosaic Model” – the puzzle pieces constantly move but always fit together • Phospholipid has 2 parts • Phosphorous head – polar, hydrophilic • Fatty acid tail – nonpolar, hydrophobic • Tails meet in the middle
The Cell Membrane • Also made of cholesterol • Inserted among the phospholipids • Gives strength to the membrane • Decreases flexibility of membrane
The Cell Membrane • Membrane proteins – 2 main types • Integral – go all the way into the lipid bilayer • Peripheral – only attached to surface of lipid bilayer
Important Properties of P.M. • Communication • Allows interaction through hormones, enzymes, antibodies, etc. • Electrochemical gradient • Gradient = difference • Inner membrane is more negative than outer membrane (important for nervous system function) • Selective permeability • Allows entry and exit of certain materials
Selective Permeability • What determines what can get in/out? • Only lipid soluble substances can pass • No big molecules can pass, only small non-polar ones • Allows for cation flow, not anion flow • Channels – allows for substances to pass with water • Transporters – shuttle substances in and out