Cell Membrane/ Electron Transport Chain / Biochemical Pathway Essay, Research Paper

1. The cell membrane structure is vital to the life of the cell. The cell membrane is shaped as having a phosphate head at the very outer surface, and two fatty acid tails hanging from it. The membrane is double, so at the tip of the fatty acid tails, there are two more fatty acid tails attached to another phosphate head. This is what it looks like:

The reason the cell membrane is shaped like this is mainly to control the water flow in and out of the cell. Water is very important to the cell: if too much water enters the cell, the cell will explode, and if too much water leaves the cell, the cell will shrivel up and die. This is how the cell membrane controls water flow: the phosphate heads are polar, and slightly attract water. However, the fatty acid tails in between are non polar, and repel water, so the fatty acid tails prevent too much water from entering or leaving the cell. With this tough membrane, there has to be a way for things to enter the cell. This is where the channel proteins come in. They act as gateways to the cell. There are many ways to enter the cell. Some ways require energy, while others don?t. The ways that require energy are put into a category called active transport, while the ways that don?t require energy are put into a category called passive transport. An example of active transport is the proton pump. The proton pump is an integral part of chemiosmosis, and it pumps protons from an area of low concentration to an area of high concentration. This requires energy since things like to move from an area of high concentration to an area of low concentration. An example of passive transport is facilitated diffusion. This is very easy since the particle is moving from an area of high concentration to an area of low concentration and through a channel protein made exactly for its size and shape.

2. These membranes are very important to the electron transport chain. This is because they house the membrane proteins that make up the electron transport chain. The two electron transport chains are similar in that they both make ATP by chemiosmosis, and they are different in the fact that they pump protons in different directions: the electron transport chain in the thylakoid layer pumps protons in the cell (from an area of low concentration to an area of high concentration) then the protons are forced out through the ATP synthetase channel. The electron transport chain in the mitochondria membrane pumps protons out of the cell (from an are of low concentration to an area of high concentration) and then they are forced into the cell through the ATP synthetase channels.

3. Biochemical pathways play a very important role in our body. A biochemical pathway is basically a group of enzymes that all work on a substrate to turn it into the end product. This is how it works: the reactant binds with the first enzyme to become reactant # 2, then reactant 2 binds with enzyme 2 to become reactant 3, and reactant 3 binds with enzyme 3 to become reactant 4, and so on. This goes on until the last reactant binds with the last enzyme forming the end product. When the cell has enough of the end product, the way it shuts the biochemical pathway is very interesting. The allosteric site of enzyme #1 is shaped like the end product, and when there is a high concentration of the end product, it binds with the allosteric site of enzyme #1, changing the shape of the active site of enzyme #1. Thus, reactant #1 can no longer bind with enzyme #1, effectively shutting down the entire process. When the cell needs more end-product, it removes the end-product from the allosteric site of enzyme #1, and reactant #1 can bind with enzyme #1 to form reactant #2, and so on. Thus, the biochemical pathway is back in business.