C1.1 Enzymes and Metabolism

• enzymes are globular proteins
• enzymes act as catalysts in metabolic reactions
• catalysts are substances that speed up the metabolic rate of reaction without changing their original shape
• metabolism is the complex network of interdependent and interacting enzyme-catalyzed reactions occurring in cells or living organisms
• every enzyme is specific and catalyzes one specific chemical reaction
• metabolism consists of anabolic and catabolic reactions
• anabolic reactions synthesize complex molecules from simple ones. i.e. macromolecules from monomers via condensation reactions
• anabolic reactions include protein synthesis, photosynthesis and glycogen formation
• catabolism reactions break down complex molecules into simpler ones i.e. macromolecules to monomers via hydrolysis
• catabolic reactions include digestion and oxidation of substrates in respiration
• the active site on an enzyme is a region where substrates bind to and are catalyzed to products
• each active site has a complementary shape allowing one substrate to bind to it
• the active site is composed of amino acids with a 3-dimensional shape
• chemical reactions occur when particles collide
• an enzyme can only catalyze a reaction when the substrate collides with the active site of the enzyme
• the more frequent collisions between substrates to active sites the faster the rate of reaction
• to increase rate of reaction in enzymes you can increase the temperature and substrate concentration. this allows for more collisions to occur
• to increase rate of reaction in enzymes you can immobilize the substrates (repeated enzymatic hydrolysis) and enzymes in the membrane (increasing stability)
• all proteins, including enzymes, have specific shapes that determine their biological function
• denaturation is the permanent damage in the shape of proteins resulting in loss of function
• denaturation is a change in the natural nature of enzymes
• if an enzyme is denatured the shape of its' active site has changed. substrates can no longer bind to it and therefore there aren't any catalyzed reactions occurring
• enzymes become denatured when they surpass their optimum temperature and pH levels
• substrate concentration affects enzyme activity, as it increases the rate of collisions increase allowing more reactions to occur. once all active sites are saturated the rate plateaus
• activation energy is the minimal amount of energy required for a reaction to occur
• enzymes lower activation energy for chemical reactions, allowing metabolism to occur
• the enzymes required for aerobic respiration are produced by mitochondrial enzymes
• enzymes required for photosynthesis are produced by chloroplast enzymes
• intracellular enzymes are active within the cells that they are produced in
• glycolysis and the krebs cycle require intracellular enzymes for metabolism
• extracellular enzymes are active outside the cell
• enzymes involved in digestion in the human gut are extracellular enzymes (these are secreted from specialized cells into the lumen of the digestive system)
• endotherms are animals that maintain a constant body temperature by the heat released from their metabolic reactions
• glycolysis in respiration is an example of a linear metabolic pathway
• the Krebs cycle in respiration and Calvin cycle in photosynthesis are examples of a cyclical metabolic pathway
• enzyme inhibitors are chemicals that can bind to an enzyme to speed up or slow down the activity of an enzyme
• enzyme inhibitors can be competitive (can bind to the active site) or non-competitive (can bind to the allosteric site)
• competitive inhibitors compete with substrates to bind to an enzyme's active site. they have similar shapes and chemistry to the substrate which allows them to do so.
• non-competitive inhibitors bind to the allosteric site of an enzyme, but it changes the active sites shape which prevents substrates from binding to the active site