Chapter 2

• simple diffusion is the spreading out of particles so they are evenly distributed over the available space
• simple diffusion is a passive process
• osmosis is the diffusion of water molecules across a semipermeable membrane from a region of high water concentration to a low water concentration
• osmosis is a passive process
• facilitated diffusion is when substances move with the concentration gradient (high -> low), but molecules are too big to fit through channel proteins so they use a carrier protein to assist it through the membrane
• facilitated diffusion is a passive process
• facilitated transport is when proteins in the cell membrane allow molecules to be transported across the membrane
• facilitated transport is a passive process
• active transport allows cells to transport material against the concentration gradient, from areas of low concentration to areas of high concentration
• active transport requires energy (ATP/Adenosine Triphosphate)
• vesicular transport is the transport of materials into or out of a cell in membrane-bound sacs (vesicles)
• vesicular transport is an active process
• endocytosis (under vesicular transport) takes liquids or solids into the cell by vesicular transport
• endocytosis has branches: pinocytosis and phagocytosis
• pinocytosis is taking liquid into the cell by vesicular transport
• phagocytosis is taking vesicles that contain solid particles into the cell
• exocytosis (under vesicular transport) is when the contents of a vesicle inside the cell are passed to the outside
• net diffusion is the movement of liquid/gas molecules from places of higher concentration to places of lower concentration
• osmotic pressure is the pressure caused by the concentration difference of water across a semipermeable membrane due to the presence of dissolved solutes (increases with higher solute concentration)
• cell theory: all living organisms are composed of cells, the cell is the basic unit of life and cells arise from pre-existing cells
• cell membrane function: physical barrier, regulates movement of materials coming in and out of the cell, first to be affected by changes in extracellular fluids, supports the tissue that the cell's apart of
• cell membranes diagram is called the fluid mosaic model
• main structure of cell membrane is the phospholipid bilayer
• every phospholipid has a hydrophilic head and 2 hydrophobic tails
• cell membrane has cholestral and molecules embedded in it
• cholestral molecules that are wedged between phospholipids make the membrane less permeable to very small water-soluble molecules that would usually be able to freely cross
• some protein molecules pass through the membrane while others are bound to the surface
• membrane protein

  receptor proteins respond to changes in extracellular fluid
• membrane protein

  channel proteins allow water soluble substances to freely pass through
• membrane protein

  carrier proteins bind to particular molecules, allow them a passage
• membrane protein

  cell identity markers allow cells to recognise cells of the same tissue and foreign invadors
• homeostasis is the maintenance of a constant environment, maintained in the extracellular fluid
• all cells need oxygen and glucose for cellular respiration, lipids, vitamins, minerals, carbohydrates and proteins
• all cells need removel of water, carbon dioxide and other waste products
• many cells produce useful substances which must exit the cell (hormones, enzymes)
• passive process doesn't require energy
• active process requires energy (ATP/Adenosine Triphosphate)
• passive transport is transport of substances across the cell membrane without the use of energy
• concentration gradient is the difference in concentration of a solution
• nucleus contains DNA and is separated from the cytoplasm by with own double membrane (nuclear membrane)