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• Diffusion


  The movement of a solute from an area of higher concentration to an area of lower concentration within a solvent. At equilibrium, there is a uniform distribution of molecules.
• Solution


  A mixture of liquids, gases, or solids in which dissolved substances are uniformly distributed. A solute dissolves in a solvent to form a solution.
• Concentration gradient


  The concentration difference of a solute between two points divided by the distance between the points.
• Osmosis


  The movement of a solvent (water) across a selectively permeable membrane.
• Osmotic pressure


  The force required to prevent the movement of water across a selectively permeable membrane.
• Types of solutions

  • Isosmotic
  • Hyperosmotic
  • Hypoosmotic
• Isosmotic solutions


  • Have the same concentration of solute particles as a reference solution
• Hyperosmotic solutions


  • Have a greater concentration of solute particles than a reference solution
• Hypoosmotic solutions


  • Have a lesser concentration of solute particles than a reference solution
• Hypotonic solution


  Cells swell (and can undergo lysis)
• Isotonic solution


  Cells neither swell nor shrink
• Hypertonic solution


  Cells shrink
• Mediated transport


  The movement of a substance across a membrane by means of a transport protein. The substances transported tend to be large, non-lipid-soluble molecules or ions.
• Mediated transport


  • Exhibits specificity (selectiveness), competition (similar molecules or ions compete for a transport protein), and saturation (rate of transport cannot increase because all transport proteins are in use)
• Channel proteins


  Form membrane channels (ion channels)
• Carrier proteins


  Bind to ions or molecules and transport them
• Uniport (facilitated diffusion)


  Moves an ion or molecule down its concentration gradient
• Symport


  Moves two or more ions or molecules in the same direction
• Antiport

  Moves two or more ions or molecules in opposite directions
• ATP-powered pumps


  Move ions or molecules against their concentration gradient using the energy from ATP
• Secondary active transport


  Uses the energy of one substance moving down its concentration gradient to move another substance across the plasma membrane
• Endocytosis


  The movement of materials into cells by the formation of a vesicle
• Types of endocytosis

  • Phagocytosis (movement of solid material into cells)
  • Pinocytosis (uptake of small droplets of liquids and the materials in them)
  • Receptor-mediated endocytosis (plasma membrane receptors attaching to molecules that are then taken into the cell)
• Exocytosis


  The secretion of materials from cells by vesicle formation
• Cytosol


  Consists of a fluid part (the site of chemical reactions), the cytoskeleton, and cytoplasmic inclusions
• Cytoskeleton


  • Supports the cell and enables cell movements. It consists of protein fibers (microtubules, actin filaments, and intermediate filaments)
• Nuclear envelope


  Consists of two separate membranes with nuclear pores
• DNA


  The hereditary material of the cell and controls the activities of the cell
• Cell division


  DNA is organized as chromatin. During cell division chromatin condenses to form chromosomes consisting of two chromatids connected by a centromere.
• Nucleoli


  Consist of RNA and proteins and are the sites of ribosomal subunit assembly
• Ribosomes


  The sites of protein synthesis
• Rough ER


  ER with ribosomes attached. It is a major site of protein synthesis
• Smooth ER


  Does not have ribosomes attached. It is a major site of lipid synthesis
• Golgi apparatus


  A series of closely packed membrane sacs that collect, modify, package, and distribute proteins and lipids produced by the ER