Cell membrane

• Plasma membrane


  Another name for the cell membrane.

  
• Fluid mosaic


  A model that says the cell membrane tends to act more like a liquid than a solid and has proteins embedded in it.

  
• Active transport


  Energy-requiring process that moves material across a cell membrane against a concentration gradient.
• Passive transport


  Movement across the cell membrane that does not require energy from the cell and moves with the concentration gradient.
• Diffusion


  Movement of molecules (oxygen, caron dioxide, natural steroid hormones) from an area of higher concentration to an area of lower concentration.

  
• Osmosis


  Diffusion of water from an area of higher concentration to an area of lower concentration. .

  
• Endocytosis


  Movement of materials into the cell by the formation of a vesicle from the infolding of the cell membrane.

  
• Exocytosis


  Removal or secretion of materials from a cell by use of a vesicle. The molecules to be exported are modified by the Golgi body

  
• Phospholipid


  specialized lipid made of a phosphate (polar), hydrophilic head and two fatty acid (nonpolar), hydrophobic tail.
• Lipid Bilayer


  Term used to describe the 2 layer thick phospholipid structure of the cell membrane.

  
• Hydrophobic


  Describes a substance that resists dissolving in water.
• Hydrophilic


  Describes a substance that is able to mix with water.
• Isotonic


  Describes a solution whose solute concentration is equal to the solute concentration inside a cell. No change in the cell shape.

  
• Hypotonic


  Describes a solution whose solute concentration is lower than the solute concentration inside a cell. Causes a cell to swell or increase in size from water entering into the cell.

  
• Hypertonic


  Describes a solution whose solute concentration is higher than the solute concentration inside a cell. Causes a cell to shrink in size from water exiting a cell.

  
• Channel proteins


  A type of transport protein in the membrane whose role is to pass large molecules (ions, sugars, & amino acids) that cannot go through the membrane.
• pump


  transport protein used to move substances against the gradient
• marker protein


  A special type of protein found in the cell membrane that helps to identify a cell

  
• facilitated diffusion


  A type of passive transport that uses a transport protein to move substances down the concentration gradient.
• Homeostatsis


  The maintenance of stable internal conditions (98.6F temperature, 7 pH body cells, 2 pH stomach) in a changing environment.
• Equilibrium


  spaced is filled with the same amount of molecules on the inside as they're are on the outside
• Concentration gradient


  substances move from an area of high concentration to an area of low concentration
• Carrier protein


  A type of transport protein in the membrane whose role is to only pass substances through the cell membrane that can fit their binding sites.
• concentration


  The amount of a particular substance in a given volume.
• Sodium-potassium pump


  ATP (energy) is used to pump sodium ions outside of the cell and potassium ions inside the cell
• vesicles


  membrane bound sacs
• • Explain the concepts of diffusion and osmosis and why they are important to cells physiology


  diffusion = tendency of all molecules to scatter evenly throughout the environment, move from higher to lower concentration, requires no energy - there must be a difference in concentration (concentration gradient)

  osmosis = movement of solvent (water) across a selectively permeable membrane
• • Explain how temperature influences the movement of a substance


  things move faster as they are heated up
• • Explain how molecular size influences the movement of a substance


  smaller size = faster movement
• Explain the purpose of wearing gloves for this experiment


  to avoid the indicator test chemicals from coming into contact with your skin
• • Elodea


  an aquatic plant of a genus that includes the ornamental waterweeds
• • Concentration

  a measure of the amount of dissolved substance (the solute) contained per unit of volume
• • Molecular motion


  the more molecular motion, (more heat) results in molecules moving faster
• • Selectively permeable membrane/Cell membrane


  the membrane is "choosy" - some substances pass freely through the bi-layer, but others - such as the sugar from a digested energy bar - require proteins
• • Molecular weight


  the lighter molecular weight will diffuse much faster, the heavier molecular weight will diffuse slower
• • Concentration gradient


  the difference in concentration on either side of a semi-permeable membrane (like a cell membrane)
• • Solute


  a chemical that dissolves in a solvent, forming a solution
• • Solvent


  a chemical in which other substances dissolve, forming a solution
• • Hypertonic


  describes a solution in which the solute concentration is greater than on the outer side of a semipermeable membrane
• • Hypotonic


  describes the solution in which the solute concentration is less than on the other side of a semipermeable membrane