Cell Membrane and Membrane Transport

• phospholipid bilayer

  A double layer of phospholipids that makes up cell and organelle membranes.

  
• concentration gradient (diffusion)

  Concentration gradient is the difference between concentrations. Diffusion is when molecules move to create equilibrium.

  
• Water always follows...

  salt, sugar, some kind of solute
• cholesterol in a cell membrane

  adds stiffness and flexibility

  
• Signaling receptor

  protein that receives information on the outside to cause the inside of the cell to respond (ex. hormones)

  
• If a cell is in a hypotonic solution, will it swell or shrink?

  swell (cytolysis)

  
• If a cell is in a hypertonic solution, will it swell or shrink?

  shrink (crenate/plasmolysis)

  
• When molecules go from low to high concentration, what two things are required?

  A carrier protein, ATP
• Energy used by cells

  ATP

  
• Items that need help crossing a cell membrane.

  large molecules like sugar, and ions like Potassium (K)
• Items that can easily diffuse across a cell membrane.

  water, gases
• solvent

  A liquid substance capable of dissolving other substances

  
• solute

  A substance that is dissolved in a solution.

  
• lipoprotein

  bonding of molecules of fat and protein

  
• marker protein

  extend across the cell membrane and serve to identify the cell

  
• vesicle

  A membrane bound sac that contains materials involved in transport of the cell.

  
• aquaporin

  water channel protein in a cell

  
• carrier protein

  A membrane protein, specifically a transport protein, holds onto molecules and changes their shapes in a way that shuttles them across the membrane.

  
• fluid mosaic model

  Structural model of the plasma membrane where molecules are free to move sideways within a lipid bilayer.

  
• hydrophilic

  water loving

  
• hydrophobic

  Water fearing

  
• Role of cholesterol in membrane

  Sits between the phospholipids in the bilayer, provides

  membrane stability.

  
• Cytolysis

  This happens when a cell swells until pressure bursts it, resulting in cell death.

  
• Plasmolysis

  The collapse of a walled cell's cytoplasm due to a lack of water.

  
• Hypertonic


  If a cell is placed in a solution and it shrivels, it was in this type of solution.

  
• Hypotonic


  If a cell is placed in a solution and it swells and eventually bursts, it was in this type of solution.

  
• Lipid bilayer

  Gives cell membranes a flexible structure that forms a strong barrier between the cell and its surroundings.

  
• Marker protein

  Act as cellular ID

  
• Hypertonic Solutions

  Solution that has a higher concentration of solutes (lower conc. of H2O). Water will leave the cell.

  
• Hypotonic Solutions

  Any solution that has a lower concentration of solutes (higher conc. of H2O). Water will enter cells.

  
• Isotonic Solutions

  Two solutions have the same concentration. Molecules will not move or move back and forth at same rate.

  
• Proteins

  Act as channels or gates through the membrane.

  
• Cell membrane

  Covers the cell's cytoplasm. Controls what moves in and out.

  
• Phagocytosis

  Endocytosis: Eating particles. (vesicles formed around solid matter)

  
• Pinocytosis

  Endocytosis: Drinking droplets of fluid (vesicles formed around liquid matter)

  
• Passive Transport


  No energy needed

  
• Active Transport

  requires energy (ATP)

  
• exocytosis


  The process of removing materials from the cell.

  
• endocytosis


  The process of taking materials into a cell (form a vesicle inside the cell.) This is an active process requiring ATP. Can be Pinocytosis or Phagocytosis.

  
• active transport

  Movement of substances across membranes against their concentration gradient, requiring the use of energy. Usually involves the use of proteins.