BIOLOGY

• The cell membrane is responsible for maintaining homeostasis
• Homeostasis is the stable internal environment
• The cell membrane maintains homeostasis by balancing the pH, temperature, glucose (sugar intake), water balance
• The Cell Membrane and Homeostasis -

  It does this through active and passive transport
• Simple Diffusion - requires no energy
• Simple diffusion's molecules move from area of high to low concentration
• Diffusion - it is a passive process which means no energy is used to make the molecules move, they have natural kinetic energy
• Diffusion's solute move down the concentration gradient (high to low)
• Osmosis - diffusion of a water across a membrane
• Osmosis moves from high to low water concentration
• Water is attracted to solutes like salt so it will alosve travel to areas of low solute concentration to high solute concentration.
• what kind of Diffusion that is high water to low water concentration?
• what kind of Diffusion that moves high to low water concentration

  Osmosis
• Diffusion of water across a membrane - High water concentration to low water concentration while low solute concentration to high solute concentration
• Cells in solution

  Isotonic

  hypotonic

  Hypertonic
• Isotonic - A solution whose solute concentration is still the same inside and outside of the cell
• Hypotonic - A solution whose solute concentration is lower than the solute concentration inside a cell
• Hypertonic - A solution whose solute concentration is higher than the solute concentration inside the cell
• What is the direction of water movement of the Isotonic solution?

  The cell is at equilibrium, water will flow in both directions outside and inside the cell
• water movement of Hypotonic - water is going inside of the cell
• water movement of hypertonic - water is going out of the cell
• Hypotonic solution is under a condition called cytolysis
• Hypertonic solution is going under the condition of plasmolysis
• Cytolysis - the destruction of a cell, cells swell and burst
• Plasmolysis - the shrinking of a cell
• Three Forms of transport across the membrane

  • simple diffusion
  • facilitated diffusion
  • active transport
• Simple diffusion - does not require energy, moves high to low concentration
• Facilitated diffusion - does not require energy, uses transport proteins to move high to low concentration
• Proteins are crucial to membrane function.

  • structural support
  • recognition
  • communication
  • transport
• Facilitated diffusion - molecules will randomly move through the pores in channel proteins
• Channel proteins are embedded in the cell membrane & have a pore for materials to cross
• Carrier proteins can change shape to move material from on side of the membrane to the other
• Active transport - requires energy or atp
• atp stand for adenosine triphosphate.
• active transport - requires energy and moves materials from low to high concentration. Against concentration gradient
• Types of active transport

  • exocytosis
  • endocytosis
  • pinocytosis
  • phagocytosis
• Exocytosis - how materials EXIT the cell
• Endocytosis - how materials enter the cell
• Pinocytosis - how smaller materials enter the cel
• Phagocytosis - how larger materials enter the cell