Clara Skepple
Miranda Wilby, Sarah Cavanagh
Thursday, March 3 2016
Observing Diffusion and Osmosis
INTRODUCTION:
Related Theory: The cell membrane is the outermost boundary of the cell, made up of proteins and lipids. This membrane holds the cell together and establishes the movement of materials that go into and out of the cell. This is a selectively permeable membrane: a barrier that allows some molecules to pass through, but prevents other molecules from penetrating (1). Passive transport is the movement of materials across a cell membrane without the use of energy from the cell. One type of passive transport is diffusion. Diffusion involves the movement of molecules from an area with a higher concentration to one with a lower concentration (1). Diffusion is affected by many things; temperature, concentration and pressure. It disperses until molecules are equally distributed within a space. Osmosis is diffusion of water through a selectively permeable membrane. Water will diffuse from the place with higher concentration to the place with a lower concentration. Water goes through the concentration gradient. Which is when molecules without energy diffuse from the place with higher concentration to the one with lower (1). The ability to diffuse through water all depends on the size of the molecule as well. For example, starch is a large molecule therefor it should not fit through the cells membrane. Starch is a polysaccharide because it is comprised of lots of sugars. Individually these glucose molecules are able to pass through the cells membrane but due to the amount of them in starch it can not pass through. Amylase is an enzyme that catalyses the hydrolysis (splitting of a compound by addition of water molecules) of starch into sugars (1). Amylase breaks the starch down into smaller sugar molecules going from C6 H10 O5 to glucose which is C6 H12 O6. The