Fitness of the body & mind - Part III (Aerobic Glycolysis)

We saw in the previous article that the first step,glycolysis in both aerobic as well as anaerobic, takes place in the cytoplasm of the cell. In this article, we will see how aerobic glycolysis is carried out.

Aerobic glycolysis, also known as Cellular respiration, requires oxygen for harvesting energy. There are 3 steps in this process: (1) glycolysis (2) Krebs cycle or citric acid cycle (3) electron transport chain. Although the glycolysis takes place in the cytoplasm of the cell, the Krebs cycle and electron transport chain occur within the mitochondria for cellular respiration. In aerobic glycolysis, mitochondria are the engines of our cells where sugar is burned for fuel and the exhaust is CO₂ and H₂O.

Irrespective of the metabolic pathways(aerobic or anaerobic), the first step glycolysis produces a total of 4 ATP molecules but 2 are used up in the process. In aerobic metabolism, additional ATPs are produced during Krebs cycle and electron transport chain resulting in a grand total of 40 ATP molecules from the breakdown of one glucose molecule. 2 ATPs are already lost in glycolysis(breakdown of glucose to pyruvic acid). To move the pyruvic acid into mitochondria, the process uses one ATP. Thus for each glucose molecule which produces 2 pyruvic acids(2 ATPs are lost here),a net total of 36 ATPs are produced as 2 more ATPs are lost to push the 2 pyruvic acids into the mitochondria.

Each pyruvic acid molecule needs to react with 3 oxygen molecules to form 3 carbon dioxide molecules and 3 water molecules.

C₆H₁₂O₆ + 6O₂ =3CO₂ + 3H₂O + (energy for the cell, ie ATP)

Or, you can write it in an alternate way(we are just re-grouping the terms),

(C₃H₆O₃ + 3O₂)+ (C₃H₆O₃ + 3O₂) = 3CO₂ + 3H₂O + (energy for the cell, ie ATP)

Remember, glucose is broken down to 2 pyruvic acid molecules as

C₆H₁₂O₆ = 2(C₃H₆O₃)

You don't need to know the details of the Krebs cycle and electron chain transport to lose/gain weight and to do exercises as it involves some technical terms! If you have to take an exam or are further interested in knowing, you can refer to any "good" text book on General Chemistry or Physiology/Anatomy.Or, you can buzz me for details through email!

Things to keep in mind:

Glucose(also known as Dextrose),Fructose(found in fruits and honey) and Galactose are simple sugars called monosaccharides. All the living cells use glucose as a source of energy and metabolic intermediate.

Sucrose(Table sugar) = glucose(50%) + fructose(50%)

Lactose(found in milk and it makes to 2-8% of milk)= glucose + galactose

Maltose(used in brewing beer) = glucose + glucose

Sucrose, Lactose, Maltose are disaccharides. Starch, a polysaccharide(complex carbohydrate) is a chain of many glucose units/molecules.

People who are lactose intolerant, basically lack the enzyme "lactase" in their body which is essential to digest the milk. This enzyme is secreted by the small intestinal villi and without this enzyme, the lactose will not be broken down into its sub units glucose and galactose. Then the unbroken lactose provide food for gut flora that produces gas. People with lactose intolerant will develop bloating and constipation. Some enzymes are available in the market.

Next time when you visit any grocery store, don't go with anybody(its not a picnic spot!)go alone and go through all the aisles reading the food labels patiently. If some names sound strange, note it down and find out. You will uncover yourself mentally. Many people gain weight for a simple reason that they don't pay much attention to the food/body and talk too much while eating. So they don't keep track of the quantity that's going into the body!!!

We will see in the next article how we can burn calories by losing bad fat and gaining muscle weight through certain exercises that keep our energy levels high. Isn't that cool?