Cellular+Respiration

=Cellular Respiration =

**__Introduction:__**
====All living organisms complete thousands of chemical reactions each day in order to survive. The sum of these chemical reactions is called the **metabolism**. There are two main types of reactions: **Synthesis** (building up) reactions that use energy to make proteins/other substances for cell growth and maintenance. **Decomposition** (breaking down) reactions that release energy for the cell to use. **Cell Respiration** is a decomposition reaction that starts with glucose and converts it to ATP, CO2 and water. This reaction occurs in small steps to protect the cell from overheating due to the high amounts of energy in glucose.====

==== **Synthesis Reaction:** Two or more simple substances combine to form a more complex substance; two or more reactants yielding one product; opposite of decomposition; reactant+reactant---> product. Example: Hydrogen gas + oxygen ---> water. ====

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 ** Decomposition Reaction: ** A more complex substance breaks down into more simple parts; one reactant yields 2 or more products; opposite of synthesis; reactant ---> product+product. Example: Water ---> Hydrogen gas + oxygen. =====

[[image:http://www.usoe.k12.ut.us/curr/science/sciber00/8th/matter/images/decompos.gif width="502" height="141" caption="decomposition: egg and turtle image"]]
http://www.usoe.k12.ut.us/curr/science/sciber00/8th/matter/sciber/chemtype.htm

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 * Cell Respiration: ** The series of chemical reactions by which a cell breaks down sugars and get energy from them. It is a decomposition pathway and each step is catalyzed with enzymes. This reaction releases CO2 and water, free energy which is stored in ATP, and energy by oxidizing glucose in a series of small steps to avoid wasting it and avoid cooking the cells. Cellular respiration is the process of oxidizing food molecules, like glucose, to carbon dioxide and water. The energy released is trapped in the form of ATP for use by all the energy-consuming activities of the cell. The process occurs in three phases: glycolysis, the breakdown of glucose to pyruvic acid; Krebs Cycle, completes decomposition of glucose and oxidation of glucose into CO2; Electron Transport Carrier, most of ATP is made.=====

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/CellularRespiration.html Image from: http://www.marinebio.net/marinescience/03ecology/mlimg/creq.jpg

__Anaerobic Respiration:__ ==== **Anaerobic Respiration** does not require oxygen and it has a different pathway for decomposition of glucose than aerobic respiration. Anaerobic respiration converts **NADH** and **pyruvates** into **NAD+** and **lactate**. The NAD+ cycles back through glycolysis. This provides very little ATP; only two per cycle. Although both anaerobic and aerobic respiration both go through gylcolysis, aerobic produces much more ATP than anaerobic. Anaerobic respiration happens using one of two possible methods: either **lactic acid fermantation** or **alcoholic fermentation**. Lactic acid builds up in muscles and can cause cramps and alcoholic fermantaion is used in yeast cells to produce ethyl alcohol. Lactic acid is used in the fast twitch muscles because there is less room for storing oxygen in these muscles. ====


 * 1) Glucose and ATP begin glycolysis in the cytoplasm. Two NADH molecules and a net of two ATP are formed.
 * 2) Then the pyruvates mix with water to produce carbon dioxide and two acetaldehyde molecules (2C's long).
 * 3) The NADH loses electrons to these molecules and becomes NAD+ which is then recycled back to gycolysis. The added electrons change the two acetaldehyde and two carbon molecules to two ethanol and two carbon molecules.



 * Aerobic respiration **, unlike anaerobic respiration requires oxygen, but alike anaerobic respiration takes place in the ** matrix of the mitochondria ** . The oxygen gets electrons from glucose and glucose-phosphates. The glucose comes from digesting carbohydrates or glycogen. The net energy gain from aerobic respiration is 36 ATP's. The reason that there are 36 instead of 38 is because when performing aerobic respiration 2 ATP's are used during the glycolysis step. This is why aerobic respiration is more efficient than anaerobic respiration. This also means that when you use aerobic respiration you get more energy from the food that you have eaten.

http://img.sparknotes.com/figures/1/18b9012870c85fba3a8046a767b52ddf/anaerobicaerobic.gif

Glycolysis (Chris/Chris/Haley)