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*Self-Practice*

Std.10th -Science Part 2

Topic 2: *Life Process in Living Organisms Part-1*

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*Today's exercise*:

1) Write the long form of the following co-enzymes and also write how many ATP molecules are obtained from them.

 a) NAD+ = .........

 b) FAD+ = ........

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 *Glycolysis*

The cells in the body of an organism need a lot of energy to survive. The storage capacity of glucose or ATP is relatively low in some cells of the brain and body.  Such cells need a constant supply of glucose through the blood. When glucose is supplied to the cells as needed, a continuous chain of energy production begins in the cell. We saw yesterday that oxidation of glucose in oxidation takes place in three stages. The first stage is 'Glycolysis'.

◆  Word glycolysis is consist of two words [Glykys : sweets or sugar Lysis : splitting or break down] Glycolysis is the process of breaking down a molecule of glucose into smaller molecules.

◆This process takes place in the cytoplasm of a cell.

◆ Oxidation causes the decompisition of a 6 carbon glucose molecule to form two molecules of 3 carbon pyruvate.

◆ Energy is required to break down the covalent bonds in glucose molecule.  Initially the reaction is accelerated using 2 ATP molecules from the cell.

◆ The glycolysis involves 10 steps and 10 enzymes. Pyruvate is the final product of glycolysis.

◆ Also in this whole process 2 molecules each of NADH, ATP and water are formed.

◆ The process of glycolysis can takes place with the help of oxygen and even without oxygen. If glycolysis occurs in presence of oxygen, the net gain is 8 ATP molecules.  (Because 3 ATPs are formed from one NADH and 2 ATPs are utilized during preparatory phase.) 

◆ Process of glycolysis was discovered by three scientists Gustav Embden, Otto Meyerhof and Jacob Paranas along with their colleagues. Hence, glycolysis is also called as Embden-Meyerhof-Parnas pathway (EMP pathway) 

◆ The whole reaction of glycolysis can be presented as follows.

 C6H12O6 + 2 NAD + + 2 ADP + 2 P -----> 2 pyruvic acid, [CH3 (C = O) COOH] + 2 ATP + 2 NADH + 2H2O

In tomorrow's article, we will learn what happens next to pyruvate.

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*Facts about glycolysis*

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◆ Pyruvate is a key product produced in the first stage of glycolysis.   While producing energy from proteins and fats, are also first converted into pyruvate.

 ■ In aerobic respiration pyruvate is converted to acetyl-co-enzyme A (acetyl-co-A) 

 ■ In anaerobic condition pyruvet is converted in to lactic acid or alcohol.

 ■ If a cell does not want to produce energy, then glucose is converted into glycogen. Energy is produced by converting glycogen back to glucose when needed.

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*Shrishail Mathapati*, kolhapur

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