cells

• the main function of the phospholipid is forming a bilayer with their hydrophilic heads and hydrophobic tails, which allows the cell to be selectively permeable.
• osmosis: a process by which molecules of a solvent tend to pass through a semipermeable membrane from a less concentrated solution into a more concentrated one.
• diffusion: movement of particles from an area of higher concentration to lower concentration
• active transport: requires energy (ATP) to move substances against their concentration gradient from low to high
• facilitated diffusion: passive transport that requires carrier proteins or channels
• a hypertonic solution is a solution with a higher concentration of solutes than the cell
• an isotonic solution has equal concentrations of solutes as the cell
• hypotonic solutions have fewer solute particles compared to the cell
• Phospholipid molecules have hydrophobic tails and hydrophilic heads, which allows them to form a lipid bilayer.
• the structure of a cell membrane is made up of phospholipids, proteins and carbohydrates. in which phospholipid molecules are arranged in a bilayer with hydrophobic tails and hydrophilic heads and proteins are embedded within the bilayer.
• osmotic pressure is the pressure exerted by water molecules on the cell membrane, created by the concentration gradient of water on one side of a membrane
• endocytosis: the taking in of matter by a living cell by invagination of its membrane to form a vacuole.
• exocytosis: a process by which the contents of a cell vacuole are released to the exterior through fusion of the vacuole membrane with the cell membrane.
• functions of the cell membrane

  • acts as a physical barrier, membrane separates the cell cytoplasm from extracellular fluid.
  • regulates passage of materials. ex entry of ions and nutrients + removal of wastes.
  • receptors sensitive to change
  • support the cell
• protein channels are channels that allow ions to pass through the membrane
• vesicular transport is the movement of substances across the cell membrane in membranous sacs called vesicles, being an active process.
• water moves from high to low water potential vice versa
• osmosis is the diffusion of water molecules across a semi-permeable membrane from a region of higher concentration to lower concentration until equilibrium is reached.
• active transport requires energy (ATP) to move against the concentration gradient
• diffusion is the net movement of particles down their concentration gradients