Hsc Biology Great Notes!

9.2 - Maintaining a Balance: 1. Most organisms are active within a limited temperature range: * Identify the role of enzymes in metabolism, describe their chemical composition and use a simple model to describe their specificity in substrates: * Role of enzymes in metabolism: * Metabolism refers to all the chemical reactions occurring in organisms * Enzymes are biological catalysts which increase the rate of chemical reactions * Without enzymes, metabolism would be too slow to support life * Chemical composition of enzymes: * All enzymes are made of protein * Proteins consist of one or more polypeptide chain. * These are composed of long chains of amino acids joined together by peptide bonds * Structure of enzymes: * In enzymes, the polypeptide chain is folded into a 3-dimensional globular shape * Part of the enzyme is called the active site. This part attaches to the substrate * The substrate are the molecules the enzymes acts upon * Specificity of enzymes: * Enzymes are highly specific in their action; this means that each enzyme acts on one substrate only * This is because the shape of the active site of the enzyme matches the shape of the substrate material * The molecules the enzyme act upon are called the substrate * The substrate molecules bind to the active site and a chemical reaction occurs * The products are the substances that the substrate(s) become. One substrate can be split, or two substrates can be joined * Models to explain specificity: * The Lock and Key Model suggests that the substrate fits exactly into the active site of the enzyme like a key fits into a lock. It assumes that the enzyme had a rigid and unchanging shape. * The Induced Fit Model states that the binding of the substrate to the enzyme ‘induces’ a temporary