In this experiment we are testing the transport of molecules from one side of the tube to the other side. Transport itself is the movement of molecules from one part of a cell to another, or from one side of the cell membrane to the other (Macmillan, 2010). The tube represents the membrane of a cell which is semipermeable, which means only certain molecules are let into and out of the cell by means of transport. The cell membrane is composed of two phospholipid layers which are separated by a fatty layer and allows the molecules entrance and exit in the cell. The phospholipids have two sides, a polar head and a non-polar tail. To create the layers, the phospholipids are lined up tail to tail and side by side to compose the two layers. This …show more content…
One type of transport is called active transport. Active transport is considered to be the movement of molecules from a place of low concentration to high concentration against the constant gradient, which is the flow of energy (Active transport, 2006). This moves molecules directly across the membrane to the other side with the help of a transport protein. Because this is going against the constant gradient and is using a transport protein, energy is needed (otherwise known as ATP in the cell). Without this energy, the transport would not be able to function. This type of transport is important because it allows the cell to maintain a different condition than its environment. Just like there are different types of transport, there are three different types of active transport: endocytosis, exocytosis, and protein …show more content…
Endocytosis is where molecules are too large to pass through the phospholipid layer, so the cell engulfs the materials to take it into the cell to be used (Active transport,2006). Exocytosis is the exact opposite of this. In this process, materials too large to pass through the membrane, such as hormones, are secreted from the cell by causing the intercellular vesicles to fuse with the plasma membrane and rid the materials into extracellular space (Exocytosis, 2009). The last type of active transport is called a protein pump, otherwise known as a sodium-potassium pump, or Na+ pump. This transport “pumps” three sodium molecules out of the cell, and takes two potassium molecules into the cell, through the cell membrane with the use of an ATP (energy) molecule (Cell membrane transport, 2007) The second type of transport is called passive transport. Unlike active transport, passive transport is the movement of molecules from a place of high concentration to low concentration (Macmillan, 2010). Also, this type of transport goes with the constant gradient, and not against it. Because of this, passive transport does not require an ATP molecule. This type of transport also has more than one subcategory. These include diffusion, facilitated diffusion, and