CELL MEMBRANE

• Cell Membrane


  Surrounds the cell and separates the components of a cell from its environment
• Cell Membrane


  Regulates the flow of materials into and out of the cell - selectively permeable
• Cell Membrane


  Helps cells maintain homeostasis - stable internal balance
• Cell membrane aka "The Phospholipid Bilayer"
• All cells have a cell membrane made of phosphate, proteins, and lipids
• Cell types


  • Prokaryotes (have a cell wall + cell membrane)
  • Eukaryotes: Animal Cells (cell membrane only)
  • Eukaryotes: Plant cells (cell membrane + cell wall)
• • Hydrophilic (water loving) phosphate heads
  • Hydrophobic (water hating) fatty acid tails
• pH


  Measure of how acidic or basic a solution is, ranging from 0-14
• Solutions with pH 0-6 are acidic, 8-14 are basic, 7 is neutral
• Buffer


  Corrects an unbalanced pH
• Homeostasis


  Stable, internal environment
• Cell Membrane


  Maintains homeostasis through balancing pH, temperature, glucose, water balance
• Passive Transport


  Movement of molecules from high to low concentration without requiring energy
• Passive Transport


  • Diffusion
  • Facilitated Diffusion
  • Osmosis
• Diffusion


  Movement of small particles across the cell membrane until homeostasis is reached
• Facilitated Diffusion


  Requires the help of carrier and channel proteins
• Isotonic Solution


  Contains the same concentration of solute as another solution, causing water to diffuse into and out of the cell at the same rate
• Active Transport


  Movement of molecules from low to high concentration, requiring energy
• Protein Pumps


  Proteins that work as pumps in active transport
• Exocytosis


  How materials exit the cell
• Endocytosis


  How materials enter the cell
• Types of Endocytosis

  • Pinocytosis (small materials)
  • Phagocytosis (larger materials)
• The cell membrane is a double layer (bilayer) of phosphates, and fats (lipids)
• The cell membrane both repels and attracts water through the membrane at the same time
• in diffusion, the particles spread out
• semi-permeable membrane is permeable to water, but not to sugar
• Hypertonic solutions - contain a high concentration of solute relative to another solution that causes water to diffuse out of the cell, causing the cell to shrivel
• Hypotonic solutions - contain a low concentration of solute relative to another solution that causes water to diffuse into the cell, causing the cell to swell and possibly explode.
• energy is required in the active transport because molecules must be pumped against the concentration gradient
• active transport uses energy (adenosine triphosphate)
• Pinocytosis

  • how SMALL materials enter the cell
  • cell drinking
• Phagocytosis

  • how LARGER materials enter the cell
  • cell eating/engulfing
• Passive transport - type of transport where NO ENERGY is NEEDED