Gen Bio 4th

• Passive Transport


  Movement of substances across the membrane without energy, from higher concentration to low concentration, down their concentration gradient
• Active Transport


  Requires energy to move a substance across a membrane, from low concentration to high concentration, against its concentration gradient
• Differentiate Passive from Active Transport
• Active Transport


  • Sodium-potassium pump
  • Amino acids moving along the human intestinal tract
  • Calcium ions moving from cardiac muscle cells
  • Glucose moving in or out of a cell
  • A macrophage ingesting a bacterial cell
• Exocytosis


  Transports molecules (such as proteins) out of the cell by expelling them in an energy-using process
• Endocytosis


  Part of the cell membrane engulf a desired macromolecule like food particles and takes them inside the cell forming tiny new food vesicles
• Phagocytosis


  • The process by which a cell engulfs material either to destroy it, to feed on it, or to get information from it

  
• Pinocytosis


  • The ingestion of liquid into a cell by the budding of small vesicles from the cell membrane
• Receptor-Mediated Endocytosis


  • A process by which cells absorb metabolites, hormones, other proteins, mediated by receptor proteins located on depressed areas of the cell membrane called coated pits
• Exocytosis transports waste materials and other secretory products out of the cell
• Passive Transport


  Doesn't need energy from the cell, substances move from an area of higher concentration to an area of lower concentration
• Kinds of Passive transportation

  • Diffusion
  • Facilitated diffusion
  • Osmosis
• Diffusion


  The net movement of material from an area of high concentration to an area with lower concentration, described as moving solutes "down the concentration gradient"
• Facilitated Diffusion


  The spontaneous passage of molecules or ions across a biological membrane passing through specific transmembrane integral proteins
• Osmosis


  The diffusion of fluids, usually water, through a semi-permeable membrane
• Types of osmosis

  • Hypertonic
  • Hypotonic
  • Isotonic
• Factors like catalysts, enzymes, and hormones can speed up, slow down or facilitate cell transport
• If the exchange of substances occur in the direction of the concentration gradient, there is no need for energy output from external factors
• If the exchange of substances occur against the direction of the gradient, inputs of extra metabolic energy are required
• The roles of cell transport mechanisms include maintaining and regulating body homeostasis, digestion and absorption of nutrients, metabolism and energy transfer, and transport of hormones, enzymes, proteins, and ions needed by the cell