Why is more than one type of enzyme required to complete the digestion process? 

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gsenviro's profile pic

gsenviro | College Teacher | (Level 1) Educator Emeritus

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Enzymes are mostly proteins (some are RNA molecules) that catalyze chemical reactions. They speed up or activate chemical reactions by providing alternate pathways.

Our digestion depends on a large number of enzymes. It is estimated that there are 50-70 thousand different enzymes in our body that support our metabolism. The enzymes are needed to break down our food into nutrients, because our digestive system is incapable of absorbing food directly (it can only absorb nutrients). These enzymes are produced in pancreas, small intestine, salivary glands and stomach. 

The reason we need more than one enzyme for digestion of food is the specificity of enzymes. We can think of this specificity as lock and key arrangement. An enzyme has an active site that can only bind with a specific food (or substrate) and hence can only break down that specific substrate. This specificity exists for particular reaction, particular functional group, particular chemical bond, etc. And hence we need more than one type of enzyme for completion of digestion.

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joyclarke | (Level 1) Adjunct Educator

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Enzymes are sometimes referred to as organic catalysts because they are substances in the body that speed up chemical reactions. 

An important characteristic of catalysts is that they are very specific, meaning that particular enzymes work on specific substrates. 

The food we eat contain different nutrients, e.g. proteins, carbohydrates,and fats.

Each of these represent a different substrate to an enzyme and therefore different enzymes are needed to breakdown each nutrient into smaller molecules that can be absorbed into the blood stream for use by the body.

For example: lipases break down fats into fatty acids and glycerol; proteases break down proteins to amino acids; and amylases break down carbohydrates to glucose.

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gsarora17 | (Level 2) Associate Educator

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Our digestive system doesn’t absorb food, it absorbs nutrients. Food has to be broken down into simpler molecules  e.g. amino acids (from proteins), fatty acids and cholesterol (from fats), and simple sugars (from carbohydrates), as well as vitamins, minerals, and a variety of other plant and animal compounds.

Digestive enzymes function to break down ingested food into usable nutrients. They help act as catalysts to break down the big molecules into smaller ones so that they can diffuse into the blood.

Enzymes tend to activate and/or degrade specific types of material. Because we eat many different types of food, carbohydrates, proteins, fats, sugars., so we need different enzymes to carry out the digestion of the different food substrates and usually more than one type of enzyme is needed for the complete digestion of a particular food.

e.g. Carbohydrases breakdown carbohydrates into monosaccharides , Lipases break down lipids into fatty acids and glycerols , Proteases break down proteins into amino acids

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ntmminor | eNotes Newbie

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Enzymes are very specific and may only be able to digest certain molecules. The digestive system also has different pH levels that may require different enzymes. For example, the stomach has a pH of around 2 so the digestive enzymes in the stomach have to be able to "survive" at that low pH. The digestive enzymes in the small intestine do not have to withstand a low pH. There are different enzymes that digest proteins, lipids, carbohydrates and even DNA. The different enzymes break the different bonds in these biological molecules.

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mrinalinisrm89 | College Teacher | eNotes Newbie

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Enzymes are mainly made up of amino acids. different enzymes act on different substrates. there are various types of digestive enzymes which act on the food we consume (which comprises of carbohhydrates, fats , proteins ).  pepsin catalyses proteins , lipases  on fats  and amylases on carbohydrate.  they break down large molecules to simple ones which are readily absorbed by the body .

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anne-gb | High School Teacher | eNotes Newbie

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Enzymes are used to break down large molecules into smaller molecules so that they can be absorbed into the blood stream. They work on a lock and key mechanism where each enzyme is specific to the shape of the molecule at the active site. Eg protease will breakdown proteins into amino acids, amylase beaks down starch into glucose and lipase breaks down fats into fatty acids and glycerol.

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