Balanced Diet and Classes of enzyme

This is a diet containing the correct proportion or the right amount of all six food substances required by an organism. The balanced diet must contain the six food classes such as carbohydrate, proteins, fats and oil, minerals, vitamins and water

DIGESTIVE ENZYMES: are organic catalyst which are complex protein substances that are manufactured by living cells. They accelerate metabolic reactions without changing their composition in the process. Enzymes are produced by both plants and animals. Enzymes may be named according to the process in which they are involved processes like photosynthesis, respiration and digestion and enzymatic in nature.

 Characteristics of Enzymes

(i)         Enzymes are specific in their actions

(ii)        Only small quantity of an enzyme is required to catalyse a reaction

(iii)       Enzymes have a specific temperature range above or below which they work become inactive or denatured. They work best at about 370c

(iv)       Enzymes do not lose their chemical composition at the end of a reaction

(v)        Enzymes are affected by the acidity and alkalinity (PH) of a medium. An enzyme which is active in an acidic medium e.g. pepsin become inactive in alkaline medium and vice versa.

(vi)       Enzymes are usually involved in reversible reaction

(vii)      Enzymes are produced by glands of the system that require that activities e.g. digestive    enzymes are produced by various gland of digestive system

(viii)     Substance called inhibitor can stop the activities of enzymes

(ix)       The activities of enzymes can be enhanced when they are joined to a co-enzymes e.g inorganic subsistence such as phosphorus.


  • PROTEASES- These are protein digesting enzymes. They are present in the stomach e.g Renin and Pepsin and also in the duodenum (Trypsin) and ileum (Erepsin). They all digest protein and break them into smaller unit.
  • AMYLASE- They are enzymes which digest starches and sugars and convert them to glucose. Ptyalin or Salivary amylase is produced by salivary gland in the mouth. It can converts starch to maltose.

Pancreatic amylase is produced in the pancreas. It converts starch to maltose, sucrose and lactose. It also converts these double sugars to their final products. Maltose to glucose, sucrose to fructose and glucose and lactose to galactose and glucose.

  • LIPASES– These are enzymes which convert and oils to fatty acid and glycerol. They are produced in the pancreas and ileum.

Digestive enzymes and functions

EnzymesSourcesLocationSubstrate acted uponEffect/product 
PtyalinSalivary glandMouthStarchPartial hydrolysis of starch to maltose
ReninGastric glandStomachProteinsIt coagulate or curdle milk
PepsinGastric glandStomachProteinsIt convert solid protein to peptones
Pancreatic LipasePancreasDuodenumFat and oilsIt converts fat and oils to fatty acid and glycerol
AmylasePancreasDuodenumStarchIt converts starch to maltose
TrypsinPancreasDuodenumProteins or peptonesIt converts proteins or peptones to polypeptide
ErepsinSuccus entricusSmall intestinePoly peptideIt converts polypeptide to amino acid



1a. Define enzyme

  1. State 5 characteristics of enzymes

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