Cellular Respiration

     What is Cellular Respiration?
  Cellular respiration is when organic molecules get together to produce energy (ATP). In cellular respiration, glucose, oxygen, and water are the reactants. The products are carbon dioxide, water, and most importantly ATP (ENERGY).

EQUATION:

       Cellular Respiration takes place in the mitochondria. There are two types of cellular respiration, aerobic and anaerobic respiration. Aerobic requires oxygen, while anaerobic does not need oxygen to perform the process. In both types, glycolysis occurs. Glycolysis occurs in the cytosol. With glycolysis, glucose and two ATP go in. The products are 2 pyruvic acids, 2 NADH, and 4 ATP. If oxygen is present, the 2 pyruvic acids go into the Krebs Cycle. The Krebs cycle occurs in the matrix of the mitochondria. Along with the 2 pyruvic acids, FAD+ and NAD+ are also going into the reaction. As a result, the products of this reaction are CO2, NADH, and FADH. Now, the NADH and FADH go into the Electron Transport Chain. In this final process, ATP is extracted from NADH and FADH. In the ETC, there is a turbine known as ATP Synthase, Due to the concentration gradient, the hydrogen ions try to meet equilibrium inside and outside the mitochondria, The hydrogens go through the ATP synthase, and bonds with an oxygen molecule creating water. ADP goes through the ATP synthase, binds with a phosphate group, and out comes ATP. During this process, about 36-38 ATP is produced.

       In anaerobic respiration, the pyruvic acid and NADH from glycolysis go to either alcoholic fermentation or lactic acid fermentation. In alcoholic fermentation, pyruvic acid and NADH go in. The products are CO2, alchohol, and NAD+. In lactic acid fermentation, the same reactants as alcoholic fermentation enter the process, but the products are lactic acid and NAD+. Then, the product NAD+ goes back to glycolysis, so the process can happen all over again. Lactic Acid fermentation is essential when you exercise. The only way you are able to keep exercising is because of lactid acid fermentation. 

Here's a video to a link that explains Cellular Respiration in more detail:

http://www.discovery.com/tv-shows/other-shows/videos/assignment-discovery-shorts-06-07-07-08-cellular-respiration.htm

Now, whats the relationship between photosynthesis and cellular respiration?

          Isn't it mind blowing that Cellular Respiration happens less than 15 microseconds? Without cellular respiration, one would not be able to survive. This process plays an essential role in the ecosystem. However, respiration in multicellular organisms require a more complex process with the respiratory system. The respiratory organs of organisms such as insects connect with their internal tissues. Similarly, respiration in vertebrates uses the circulatory system. This system holds gases between cells and organs. 
         In order to use the respiratory system, the respiratory system needs to be big enough to take in large amounts of oxygen. This happens so the organisms can take in oxygen and release waste gas. In addition, respiratory membranes need to be wet, so the gases can get across the membrane. An animal that uses this process is an earthworm. An earthworm uses its body as a respiratory organ. If you pay close attention, you probably notice that earthworms have moist outer skin. This benefits them when they go through cellular respiration. The moist surface allows oxygen to go across and go into the blood, which is present in the dense capillary snare (right below the skin). In fact, blood brings the oxygen to the body cells. When it gets to the body cells, carbon dioxide carries the oxygen to the skin capillaries. Then, they diffuse out of the body. Earthworms go through a more complex process because small animals have a high ratio of surface to volume.

            Cellular Respiration is crucial to all organisms, even though it might vary in the way it is performed. It's amazing how fast these process happen in the body. We take advantage of our every breath. In fact, we fail to realize how much our body does for us so we can live. 

Cell Membrane

Jina Joseph
AP Bio
10.3.14   

The Cell Membrane 

     The cell membrane is very important to the body. Yet, some people fail to see and appreciate the cell membrane and it's ability to keep the body functioning. Did you know that one of the earliest moments of evolution may have been the formation of a membrane that enclosed a solution? Every organism is made up of cells. All cells are contained by a cell membrane. The cell membranes are made up by phospholipids and proteins, and are sometimes known as "phospholipid bi-layer".

Above is a model of a cell membrane. The spheres are the phosphate end, which means they are soluble and hydrophilic. The extensions, also known as the tails, are hydrophobic.

      A membrane is held together by hydrophobic interactions, which are weaker than covalent bonds. The movement of phospholipids in the membrane are quick. Phospholipids, which are next to each other, switch positions about 10^7 times per second. A membrane is constantly fluid as a temperature decreases until the phospholipids create a closely packed arrangement. The membrane brings it's fluid to a lower temperature when there are rich phospholipids with unsaturated hydrocarbon tails. Due to the kinks located in the tails, unsaturated hydrocarbon tails cannot be placed closely together. 

      The cell membrane is selectively permeable. This means that the cell only allows certain things to go in and out of the cell. In fact, this is one reason the membrane is structured this way. Due to the way it is structured, there is a greater ratio of surface area to volume allowing the flow of molecules in and out of the cells at an easier way. Particles with no charge can pass through the membrane. Some molecules have charges so it is more difficult to get across the membrane. Proteins such as a channel protein and an aquaporin helps molecules to get in and out of the cell membrane. A membrane is also known a a mosaic fluid because its consists of various proteins.  Integral proteins and Peripheral proteins are two out of the hundreds of proteins in a person's body. Integeral proteins go through the hydrophobic center of the lipid bilayer, while peripheral proteins are not in the lipid bilayer, but they are appendages connected to the surface of the membrane. On the cytoplasmic side of the membrane, membrane proteins are retained in place by the cytoskeleton. On the extracellular side, some membrane proteins are connected to fibers of the extracellular matrix. The membrane alone could not provide support to the cell. 

     Diffusion is the result of thermal motion. Diffusion is the movement of molecules of any substance so that they spread out evenly into available space. Processes such as diffusion and facilitated diffusion use passive transport because there is no energy being used. The diffusion of water across the cell membrane is known as something specific, osmosis. Now this relates to the tonicity of a solution. The tonicity of a solution depends the concentration of the solution that cannot cross the membrane. Cells without walls are seen in three enviroments: isontonic, hypertonic, and hypotonic. In an isotonic enviroment, there will be no net movement. The solutes concentration is the same on the inside and outside of a cell meaning the state of equilibrium has been reached. A hypertonic solution is when there is more concentration on the outside of the cell. On the other hand, the hypotonic solution is when there is more concentration in the inside of the inside of the cell.

In a hypotonic solution, the cell can burst or result in lysed. This means that their is too much water in the cell. On the contrary, hypertonic solutions can result in cells shrinking because the solution continues to decrease.