I/GCSE Biology Chapter Analysis - Chapter 2: Structure and Function of Living Organisms - Biological Molecules
Excellent, let's dive deeper into the IGCSE Biology Chapter 2 sub-topic on Biological Molecules. This time, we'll not only cover the chemical elements, structure, and role of enzymes, but also how temperature and pH changes can affect enzyme function.
Chemical Elements in Biological Molecules:
The three main classes of biological molecules are carbohydrates, proteins, and lipids. Each of these molecules is composed of specific chemical elements:
- Carbohydrates: Carbon (C), hydrogen (H), and oxygen (O)
- Proteins: Carbon (C), hydrogen (H), oxygen (O), nitrogen (N), and sometimes sulfur (S)
- Lipids: Carbon (C), hydrogen (H), and oxygen (O)
The presence and ratio of these elements determine the unique properties and functions of each type of biological molecule.
Structure of Biological Molecules:
Biological molecules are large, complex structures made up of smaller, basic units.
- Carbohydrates:
- Carbohydrates are composed of simple sugar units called monosaccharides, such as glucose and fructose.
- These monosaccharides can be joined together to form disaccharides (e.g., sucrose) and polysaccharides (e.g., starch and glycogen).
- Proteins:
- Proteins are made up of amino acids, which are linked together in a specific sequence to form a polypeptide chain.
- The polypeptide chain then folds into a unique three-dimensional structure, which determines the protein's function.
- Lipids:
- Lipids are composed of fatty acids and glycerol.
- Fatty acids can be joined to glycerol to form triglycerides, the main type of lipid found in fats and oils.
- Lipids also include phospholipids, which are the main components of cell membranes.
The structure of these large biological molecules is crucial in determining their function and role within the living organism.
Enzymes as Biological Catalysts:
Enzymes are biological catalysts that speed up chemical reactions in the body without being consumed or altered themselves. They do this by lowering the activation energy required for the reaction to occur.
Enzymes are made up of proteins and have a specific three-dimensional shape that allows them to bind to their substrates (the reactants of the chemical reaction) and facilitate the reaction. This shape is crucial for the enzyme's function, as it determines the type of reaction the enzyme can catalyze.
Effect of Temperature on Enzyme Function:
Temperature changes can affect the shape of an enzyme's active site, which is the region where the substrate binds. As the temperature increases, the enzyme's active site can become denatured, meaning the shape is altered, and the enzyme can no longer bind to its substrate effectively. This reduces the enzyme's catalytic activity. Conversely, as the temperature decreases, the enzyme's activity also decreases.
Effect of pH on Enzyme Function:
The pH of the surrounding environment can also affect enzyme function. Each enzyme has an optimum pH range in which it functions best. Changes in pH can alter the ionization of the amino acids in the active site, leading to changes in the enzyme's shape and, consequently, its ability to bind to the substrate. Extreme pH values can cause the enzyme to denature, resulting in a loss of catalytic activity.
Work hard for your I/GCSE Biology examination!
End of analysis. Great!
