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1- Polar molecule
2- Hydrogen bonds
3- Specific heat
4- Surface tension
Lesson (4) Chemical reactions inside organisms' bodies
Biological chemical reactions occur inside living organisms body in order to help in growth, get energy, build tissues and sustain life. These reactions are called " Metabolism". If these reactions stop in a living organism, it will die.
Metabolism: A group of biochemical reactions which occur within living organisms in order to build complex macromolecules from simple molecules, or break up molecules to get energy.
Metabolism reactions are divided into:-
1- Anabolism
2- Catabolism
Anabolism: A process by which simple molecules are used to build complex macromolecules through a group of chemical reactions which consume energy.
à Building proteins from amino acids is an example on anabolism
Catabolism: A process by which energy is being released from the chemical bonds in some molecules such as glucose.
à Cells break up glucose to release energy from it.
à Chemical reactions generally need high activation energy to occur. To decrease the energy used by cell in biochemical reactions occurring inside it, we need catalysts to decrease activation energy needed for the reaction to occur, which speeds this reaction up. Such catalysts are called enzymes
Activation energy: The minimum energy required for a chemical reaction to occur.
(For reading only): The term activation energy was coined by Swedish scientist Arrhenius in 1889 A.D.
Enzymes: Biological catalysts formed from proteins molecules which speed up chemical reactions occurring within living organisms.
Enzymes are formed from groups of amino acids which are arranged in the form of polypeptide chains which forms the stereoisomerism of enzymes.
(For illustration) stereoisomer: Molecules that have the same no. of atoms but with different arrangements.
The properties of enzymes
1- They resemble chemical catalysts, as they only speed up the chemical reaction without taking part in it.
2- Enzymes are affected by the concentration of hydrogen ions (pH) and temperature.
3- Enzymes are different from other catalysts because every enzyme is specialized for only one reactant substance (called substrate) and a small no. of reactions.
4- Enzymes decrease the activation energy needed for chemical reactions to occur.
Substrate: The substance on which enzyme work.
Enzymes are classified according to their chemical structure into:-
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