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Enzymes are biomolecules that catalyze, or increase the rate of, chemical reactions. Proteins are responsible for nearly all enzymes, but RNA molecules can be catalysts, too. In the beginning of the process, the enzymes that start the chemical reaction are call substrates; these substrates convert the molecules into what is termed the product. Because enzymes only use certain substrates, they speed up only certain reactions among many, many possibilties. Therefore, the set of enzymes in a cell determine what metabolic pathways occur in that cell.
Metabolic pathways are a series of chemical reactions that occur within a cell. In each pathway, a main chemical is modified, or changed, by chemical reactions that are sped up by enzymes. Often, dietary minerals, vitamins, and cofactors are necessary in order for these enzymes to function properly. For example, for older pets, people must purchase dietary supplements which enable digestive enzymes to help with their metabolism, which is a step-by-step modification of the initial molecule to shape it into another product to be stored by the cell, to be used immediately as a metabolic product, or to initiate another meatbolic pathway, called a flux generating step.
Enzymes are protein catalysts that speed things up or in short accelerate the biochemical reactions taking place in the body.
When we eat food, we chew it. Hence large food molecules like starch, protein and fats are insoluble and big enough to pass into the bloodstream directly. Here enzymes further break it into small molecules that can be absorbed directly in bloodstream.
Enzymes are specific. There are three main enzymes in our system:-
- Protease (Breaks down protein molecules)
- Lipase (Breaks down fat molecules)
- Amylase (Sugar-degrading enzymes)
A protein molecule is made up of many different amino acids. Proteins are broken down into amino acids in the stomach and small intestine.
A starch molecule is made up of many glucose molecules. It is broken down into glucose in the mouth and small intestine.
A fat molecule is made up of fatty acid and glycerol molecules. Fats are broken down into fatty acids and glycerol in the small intestine.
The simple definition for enzyme is: A protein which acts as a catalyst for reactions in cells or organisms. A catalyst is a chemical substance which speeds up a reaction but does not get used up during the reaction. Enzymes are very specific. This means that an enzyme which acts on fats does not act on carbohydrates.
An enzyme also has an optimum temperature and pH. The word optimum means best. The enzyme works best on the optimum temperature and pH. Above or below the optimum temperature or pH, the enzymes will slow down or either be denatured. When talking about optimum pH, some enzymes works best on acidic conditions (like in the stomach) and some works best in alkaline conditions (like in the duodenum).
There are 2 types of enzymes. They are intra cellular enzymes and extracellular enzymes. All enzymes are made inside cells. Most of them remain inside the cell to speed up reactions in the cells (intracellular enzymes) while some others are let out to work in systems such as the digestive system, in stomach, for example. These are called extracellular enzymes.
Enzymes can build up or break down substances. The building up reaction is called "anabolic" while the breaking down reaction is called as "catabolic" reaction.
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