9th Class Biology Chapter 6 Notes

Important Notes of Chapter No.6: Enzymes or 9th Class Biology Chapter 6 Notes written by Honorable Sir Adnan Haider Suib. These notes are very helpful in the preparation of 9th Class Biology Chapter 6 Notes for students of the 9th class Biology Urdu Medium and these are according to the paper patterns of all Punjab boards.

Summary and Contents:
Topics which are discussed in the notes are given below:
  • Very Important Multiple Choice Questions (MCQs) of Chapter No.6 Enzymes Urdu Medium.
  • The life of living organisms is a reflection of what is going on in their bodies. Metabolism is the set of biochemical reactions that occur in living organisms in order to maintain life. These processes allow organisms to grow and reproduce maintain their structures, and respond to their environments.
  • Anabolism includes the biochemical reactions in which larger molecules are synthesized while catabolism includes the biochemical reactions in which larger molecules are broken down. Usually, energy is released in catabolism and it is utilized in anabolism. In this way the biochemical reactions are actually energy transfers.
  • During metabolism, chemicals are transformed from one form to the other by enzymes. Enzymes are crucial to metabolism because they act as biocatalysts and speed up and regulate metabolic pathways.
  • Enzymes are proteins that catalyze (i.e. speed up) biochemical reactions and are not changed during the reaction. The molecules at which enzymes act are called substrates, and enzyme converts them into different molecules, called products.
  • All chemical reactions require activation energy. It is defined as minimum energy required to start a reaction. The need for activation energy acts as a barrier to the beginning of reaction as symbolized in the diagram). Enzymes lower such barriers by decreasing the requirement of activation energy. Thus, in the presence of enzymes, reactions proceed at a faster rate.
  • Enzymes lower the activation energy in several ways. They may alter the shape of substrate and reduce the requirement of energy for this change. Some enzymes do so by disrupting the charge distribution on substrates. Enzymes may also lower activation energy by bringing substrates in the correct orientation to react. 
  • Enzymes can be categorized on the basis of the site where they work i.e. they may be intracellular enzymes (e.g. enzymes of glycolysis working in the cytoplasm) or may be extracellular enzymes (e.g. pepsin enzyme working in the stomach cavity)
  • Characteristics Of Enzymes: In 1878, German physiologist Winhelm Kuhne first used the term enzyme. Enzymes are globular proteins Like all proteins, enzymes are made of long linear chains of amino acids that fold to produce a three-dimensional molecule.
  •  Almost all enzymes are proteins i.e. they are made of amino acids.
  • Most enzyme reaction rates are millions of times faster than those of comparable uncatalyzed reactions. As with all catalysts, enzymes are not consumed by the reactions they catalyze. 
  • Enzymes are usually very specific for the type of reaction and for the nature of their substrates.
  • Only a small portion of enzyme molecule is directly involved in catalysis. This catalytic region is known as active site It recognizes and binds substrate and then carries out reaction.
  • Enzyme production can be enhanced or diminished by a cell according to needs. Enzyme activity can also be regulated by inhibitors and activators.
  • Uses of enzymes: Enzymes are extensively used in different industries for fast chemical reactions. For example;
  • 1. Food industry: Enzymes that break starch into simple sugars are used in the production of white bread, buns etc.
  • 2. Brewing industry: Enzymes break starch and proteins. The products are used by yeast for fermentation (to produce alcohol).
  • 3. Paper industry: Enzymes break starch to lower its viscosity that aids in making paper.
  • 4. Biological detergent: Protease enzymes are used for the removal of protein stains from clothes. Amylase enzymes are used in dish washing to remove resistant starch residues.

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