Chemical reactions in organism’s bodies ( Metabolism & Enzymes )


Living organisms life depends on the occurrence of chemical reactions inside their bodies , these reactions are called metabolismMetabolism  is necessary for growth , repairing the damaged tissues and obtaining the energy .

Metabolism is a group of biochemical reactions take place inside the living cells , in which : Some molecules are broken down to extract the chemical energy stored in their chemical bond , This process is called catabolism .

Complex and macromolecules are being built from simple molecules , This process is called anabolism , Metabolism is divided into the catabolism and the anabolism .

The catabolism is the process of breaking down of macromolecules into simple ones to extract the energy stored in the chemical bonds of these molecules , such as releasing the energy from the glucose oxidation process during cellular respiration .

Anabolism is the process of using simple molecules for building more complex substances throughout a chain of chemical reactions that consume the energy , such as synthesis of proteins from amino acids and Photosynthesis in green plants .




In order to biochemical reactions ( metabolism ) to occur , They need high activation energy to get started , Therefore , There should be a catalyst ( enzyme ) to reduce the activation energy , to reduce the cell consumption of more energy and to ensure the occurrence of the chemical reaction more rapidly .

Activation energy is the minimum energy needed in order for a chemical reaction to occur .

Enzymes are biological catalysts made up of protein molecules and increase the speed of chemical reactions inside the cell .

The origin of word Enzyme : Enzyme is a Latin word means ( in the yeast ) where the enzymes had been discovered at the first in the process of glucose fermentation into alcohol by the yeast .

Properties of Enzymes

Enzymes participates in the chemical reactions inside the cell to speed up them without being affected or consumed ( they are similar to the other chemical catalysts ) .

Enzymes are highly specific than other chemical catalysts where each enzyme is specific to : one reactant substance called substrate and One type or few types of reactions .

Enzymes lower the activation energy needed to get the reaction stared .

Enzymes are affected by hydrogen ion concentration ( pH ) and temperature in their action .

Factors affecting the speed of enzyme action

Temperature , Hydrogen ion concentration ( pH ) , Enzyme concentration , Substrate concentration and Presence of inhibitors .


Enzymes are sensitive to thermal changes because they are made up of protein substances .

Enzymes activity is determined in a narrow range of temperatures ( comparatively to the ordinary chemical reactions ) , Where : Each enzyme has an optimal temperature at which the enzyme is more active and it ranges between 37 : 40 degree Celsius .

Enzyme optimal temperature is the temperature at which the enzyme is more active ( 37 : 40 degree Celsius ) , The enzyme minimal temperature is the temperature at which the enzyme is less active .

The enzyme activity gradually decreases , as the temperature rises more than the optimal temperature until it reaches a certain temperature at which the enzyme activity stops due to the change of its normal composition and the enzyme will not return back to its activity by decreasing temperature .

When the temperature decreases below the optimal temperature , the enzyme activity decreases until the enzyme reaches a minimum temperature at which the enzyme activity is the least and it stops completely at 0 degree Celsius , but the enzyme restores its activity ( reactivated once more by rising the temperature .

Life application

Temperatures are recorded on some detergents to use them properly in order to the activity of enzymes they contain do not affected .


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