BIOLOGY_CELLULAR+RESPIRATION

= CELLULAR RESPIRATION =
 * A. OVERVIEW**
 * 1) =====Cellular respiration is the process by which the chemical energy of "food" molecules is released and partially captured in the form of ATP.=====
 * 2) =====It is the process of oxidizing food molecules, like glucose, to carbon dioxide and water.=====
 * 3) =====The energy released is trapped in the form of **[|ATP]** for use by all the energy-consuming activities of the cell.=====
 * 4) =====Carbohydrates, fats, and proteins can all be used as fuels in cellular respiration, but glucose is most commonly used as an example to examine the reactions and pathways involved.=====
 * 5) Cellular Respiration is also known as '[|oxidative] [|metabolism]'
 * 6) Cellular respiration is the process that allows organism to obtain food
 * 7) A living cell need to learn how to control energy. They release energy in food molecules a little bit at a time.
 * 8) Organisms get the energy they need in food.
 * 9) Food provides living things with building blocks need to grow and reproduce
 * Energy in food is a calorie. A calorie is the amount of energy need to raise 1 gram of water to raise it 1 degree celius.
 * Cells don't just burn down the energy in food. They break down gradually in key steps and capture energy.
 * They release energy in food molecules a little bit at a time which allows ATP to be formed.
 * Cellular respiration requires oxygen and a food molecule. This gives off carbon dioxide, water, and energy.
 * 1) The energy stored in ATP can then be used to drive other cellular processes like [|biosynthesis], [|locomotion] or transportation of molecules across [|cell membranes]
 * 2) The reactions involved in respiration are [|catabolic reactions] that involve the [|oxidation] of one molecule and the [|reduction] of another molecule.
 * 3) =====Cellular respiration happens in 3 metabolic processes:=====
 * Glycolysis which occurs in the cytosol
 * The Krebs Cycle takes place in the matrix of the motochondrial
 * Electron transport chain is carried out on the inner mitochondrial membrane.
 * ======In the absence of oxygen, respiration consists of two metabolic pathways: glycolysis and fermentation. Both of these occur in the cytosol.======

**B. THREE PROCESSES OF CELLULAR RESPIRATION:** Glycolysis, Krebs Cycle, Elctron Transport Chain
Cellular Respiration captures energy in three stages: glycolysis, Krebs cycle, and the electron transport chain

**Overview of three Processes**

 * Glycolysis takes place in the cytoplasm of the cell while the Krebs cycle and electron transport chain takes place in the mitochondrian (structures within the cells that help convert food into energy for cells).
 * Food molecule enter the glycolysis but only use a small amount of energy to make ATP
 * At the end of the glycolysis there is still 90% of energy from teh food moelcules unused and still locked in the pyruvic acid
 * The pyruvic acid then enters the Krebs Cycle where more energy is used
 * The bulk of the energy is extracted in the Electron Transport Chain. They are able to extract so much energy because of oxygen
 * 1) **GLYCOLYSIS**: "Sugar-breaking"
 * Glycolysis takes place in the cytoplasm of the cell while Krebs Cycle & Electron Transport chain both take place in the Mitochondrian (structure of cell that help convert food into energy for cells
 * 6-carbon sugar (glucose) is broken down into 2 molecules of a 3-carbon molecule called pyruvate. This change is accompanied by a net gain of 2 ATP molecules and 2 NADH molecules. **6 glucose --> 2 pyruvates + 2 net ATP + 2 NADH molecules** ?
 * During glycolysis, 1 molecule of glucose, & 6 carbon-compound ---> 2 molecules of pryruvic acid, a 3-carbon compound
 * The **cells** get a net gain of 2ATP for every glucose that enters the glycolysis.

>> >> 2 ATP are used to start the glycolysis but 4 ATP are produced as an end result. ( Ex: You give money to the bank and you get interest.) >> >> The **cells** get a net gain of 2ATP for every glucose that enters the glycolysis. >> >> 4 ATP are synthesized from 4ADP >> >> The process of glycolysis is so fast that they can produce thousands of ATP in a few milliseconds. > >> > >> One of the reactions of glycolysis removes 4 electron and passes them to NAD+ > >> NAD+ then changes to NADH and hold the electrons until they transfer them to other molecules > >> These high-energy electrons can be used to make more ATP
 * **ATP Production:** Glycolysis is an energy-releasing process but before it can release energy, it needs to use a little to start.
 * **NADH Production**:



When there is oxygen, pyruvic acid are produces in glycolysis and passes to the Krebs cycle. > - Since glycolysis does not require energy, they can quickly supply chemical energy when oxygen is not available. > - This advantage is big when the demand for energy suddenly increases. > a. The krebs cycle begins when pruvic acid produced by the glycolysis is passed into the matrix b. As the krebs cycle begins, acetyle CoA adds the 2 carbon acetyl group to a 4-carbon molecule already present in the cycle, producing a 6-carbon molecule called citric acid. a. Citric acid is broken down into a 4-carbon molecule, carbon dioxide is then released, and electrons are transferred to energy carriers. b. Every turn at the cycle ADP are converted into ATP molecules. 1.6 Electron Transport and ATP synthesis
 * The Advantage of Glycolysis**
 * 1) During the Krebs cycle, pyruvic acid is broken down into carbon dicide in a series of energy-extracting reactions.
 * 2) Citric acid is the the first compound formed so the krebs cycle is also known as the citric acid cycle.
 * 3) **Citric Acid Production**
 * 1) **Energy Extraction**

a. NADH and FADH2 pass their high-energy electrons to the electron transport chain. b. In eukaryotes, the electron transport is composed of a series of electron carries located in the inner membrane of the mitochondrian c. In the prokaryotes, the same process is located in the call membrane. d. Oxygen serves as the final electron acceptor of the electron transport chain. Without Oxygen the chain cannot function.
 * 1) Products from the Krebs Cycle and glycolysis feed into the electron transprot chain
 * 2) The electron transport chain uses the high-energy electrons from glycolysis and the krebs cycle to convert ADp into ATP.
 * 3) **Electron Transport**

1.2.x CELLULAR RESPIRATION VS. PHOTOSYNTHESIS > food. > Plants, animals, fungi, protists, and most bacteria = =
 * All organism use cellular respiration to break down food, but we never run out of oxygen
 * Photosynthesis balances cellular respiration by releasing oxygen.
 * Photosynthesis removes carbon dioxide from the atmosphere and cellular respiration puts it back.
 * Photosynthesis releases oxygen into the atmosphere and cellular respiration uses oxygen to release energy from
 * Cellular respiration takes place nearly in all life:
 * Photosynthesis only take place in plants, algae, and some bacteria.