Can you explain what is cell respiration?

Question

My teacher is teaching me that,but i really doesn't under stand it,

I need ur help!

Answer 1

Metabolic reactions and processes that take place in a cells to convert biochemical energy from nutrients into adenosine triphosphate ATP, and then release waste products.

Answer 2

http://www.phschool.com/science/biology_...

Awesome website that explains everything about cell repiration. It has diagrams, too.

Answer 3

Cellular Respiration:



An analogy can be drawn between the process of cellular respiration in our cells and a car. The mitochondria are the engines of our cells where sugar is burned for fuel and the exhaust is CO2 and H2O. Note that in a car that burned fuel perfectly, the only exhaust should theoretically be CO2 and H2O also.

There are three steps in the process of cellular respiration: glycolysis, the Krebs cycle, and the electron transport chain.



In contrast to fermentation, in the process of cellular respiration, the pyruvic acid molecules are broken down completely to CO2 and more energy released. Note that three molecules of O2 must react with each molecule of pyruvic acid to form the three carbon dioxide molecules, and three molecules of water are also formed to “use up” the hydrogens. As mentioned above, in glycolysis, a total of four molecules of ATP are produced, but two are used up in other steps in the process. Additional ATP is produced during the Krebs Cycle and the Electron Transport Chain, resulting in a grand total of 40 ATP molecules produced from the breakdown of one molecule of glucose via cellular respiration. Since two of those are used up during glycolysis, in prokaryotes a net total of 38 molecules of ATP are produced by cellular respiration. Most prokaryotes have very simple cells which lack several types of organelles present in eukaryotes, and therefore the Krebs Cycle and the Electron Transport Chain occur in the cytoplasm and/or using chemicals embedded in the cell membrane. In contrast, eukaryotes have more complex cells with more specialized organelles to perform given functions. In eukaryotes, the Krebs Cycle and Electron Transport Chain occur within the mitochondria, and thus the pyruvic acid resulting from glycolysis must be sent into the mitochondria for these reactions to occur. However, to move one molecule of pyruvic acid (remember each molecule of glucose turns into two pyruvic acid molecules) from the cytoplasm into a mitochondrion “costs” the cell one molecule of ATP (therefore two ATPs for a whole glucose), thus a net total of 36 ATP molecules per molecule of glucose is produced in eukaryotes as compared to only two in fermentation. The overall reaction for cellular respiration is C6H12O6 + 6O2  6CO2 + 6H2O (+ energy for the cell to use for other things).

    

Pyruvic Acid + 2 H+

+ 3 O2









3 Carbon Dioxide

+ 3 H2O

+ 34 ATP

In glycolysis and the Krebs cycle, there are also a number of electrons released as the glucose molecule is broken down. The cell must deal with these electrons in some way, so they are stored by the cell by forming a compound called NADH by the chemical reaction, NAD+ + H+ + 2e–  NADH. This NADH is used to carry the electrons to the electron transport chain, where more energy is harvested from them.

In eukaryotes, the pyruvic acid from glycolysis must be transferred into the mitochondria to be sent through the Krebs cycle, also known as the citric acid cycle, at a “cost” of one ATP per molecule of pyruvic acid. In this cycle, discovered by Hans Krebs, the pyruvic acid molecules are converted to CO2, and two more ATP molecules are produced per molecule of glucose. First, each 3-carbon pyruvic acid molecule has a CO2 broken off and the other two carbons are transferred to a molecule called acetyl coenzyme A, while a molecule of NADH is formed from NAD+ for each pyruvic acid (= 2 for the whole glucose). These acetyl CoA molecules are put into the actual cycle, and after the coenzyme A part is released, eventually each 2-carbon piece is broken apart into two molecules of CO2. In the process, for each acetyl CoA that goes into the cycle, three molecules of NADH, one molecule of FADH2, and one molecule of ATP are formed (= 6 NADH, 2 FADH2, and 2 ATP per whole glucose).



The electron transport chain is a system of electron carriers embedded into the inner membrane of a mitochondrion. As electrons are passed from one compound to the next in the chain, their energy is harvested and stored by forming ATP. For each molecule of NADH which puts its two electrons in, approximately three molecules of ATP are formed, and for each molecule of FADH2, about two molecules of ATP are formed.



Many of the compounds that make up the electron transport chain belong to a special group of chemicals called cytochromes. The central structure of a cytochrome is a porphyrin ring like chlorophyll but with iron in the center (chlorophyll has magnesium). A porphyrin with iron in the center is called a heme group, and these are also found in hemoglobin in our blood.

At the last step in the electron transport chain, the “used up” electrons, along with some “spare” hydrogen ions are combined with O2 (we finally got around to the O2) to form water as a waste product: 4e- + 4H+ + O2  2H2O.

  

Answer 4

Cellular respiration

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Cellular respiration in a typical eukaryotic cell.Cellular respiration is the set of the metabolic reactions and processes that take place in a cells to convert biochemical energy from nutrients into adenosine triphosphate (ATP), and then release waste products. The reactions involved in respiration are catabolic reactions that involve the oxidation of one molecule and the reduction of another.

Nutrients commonly used by animal and plant cells in respiration include glucose, amino acids and fatty acids, and a common oxidizing agent (electron acceptor) is molecular oxygen (O2). Bacteria and archaea can also be lithotrophs and these organisms may respire using a broad range of inorganic molecules as electron donors and acceptors, such as sulfur, metal ions, methane or hydrogen. Organisms that use oxygen as a final electron acceptor in respiration are described as aerobic, while those that do not are referred to as anaerobic.

The energy released in respiration is used to synthesize ATP to store this energy. The energy stored in ATP can then be used to drive processes requiring energy, including biosynthesis, locomotion or transportation of molecules across cell membranes. Because of its ubiquity in nature, ATP is also known as the "universal energy currency".