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Cell Structure and Transport Unit Review I Can… Explain how fundamental life processes depend on the physical structure and chemical activities of the cell. [CAPT Std. 10.1] I Will… • Describe the similarities and differences in the basic structure of plant and animal cells [D 27] • Explain the role of the cell membrane in supporting cell function. [D 30] Tenets of Cell Theory: • All living things are made of cells • All cells are produced/arise from other preexisting living cells (all cells come from cells) • The cell is the basic unit of life Cell theory is a unifying biological concept All cells • Tend to be microscopic • Must have • A cell membrane • Cytoplasm There were two broad categories of cells: Prokaryotic Cells • Primitive • e.g. Bacteria • No nucleus • No membranebound organelles • Only single-cell microscopic organisms • • • • Eukaryotic Cells Complex (you) Nucleus • Protects DNA and regulates access to it Membrane-bound organelles Can be single-cell or form multicellular organisms Key Eukaryotic Cell Organelles • • • • • • • Cell membrane Cytoplasm Cytoskeleton Nucleus Nucleolus Ribosomes Endoplasmic Reticulum • Smooth E.R. • Rough E.R • Golgi apparatus * Plant cells only **Animal cells only ***Debate whether in plants • • • • • • • • • Mitochondria Vesicles Vacuoles Large central vacuole* Lysosome*** Centrosome Centriole** Chloroplast* Cell wall* Cell Membrane Two key functions: Regulate what goes in and out of the cell Cell to cell communication Form & Function Selectively Permeable Fluid Mosaic Model • Phospholipid bilayer with embedded cholesterol and protein molecules and glycolipids and glycoproteins on the surface. Phospholipid• Polar phosphate/glycerol head • Hydrophilic • Nonpolar fatty acid tails • Hydrophobic Cell to cell communication Movement Across the Membrane Passive – No cell energy (ATP) used • • • Diffusion – Concentration gradient • Crosses lipid bilayer • Small, nonpolar/no charge Facilitated diffusion – Protein channels • Concentration gradient • Small, charged ions and highly polar molecules Osmosis – Diffusion of H2O molecules • Concentration gradient • Lipid layer movement • Aquaporin protein channels Isotonic – • Equal pull on the water • Extracellular and intracellular concentrations of water solvent and solutes are equal • Already in dynamic equilibrium Osmosis Hypotonic – • Less pull on the water • Extracellular solution has • Less solute concentration • Greater water solvent concentration • Water is pulled into the cell Osmosis Hypertonic – • Greater/more pull on the water • Extracellular solution has • Greater solute concentration • Less water solvent concentration • Water is pulled out of cell Osmosis Movement Across the Membrane Active Transport – Requires cell energy - ATP used • Protein Transport Pump • Move particles against concentration gradient • Low to high • Small, charged ions Endocytosis Exocytosis
