Maintaining a Balance

Maintaining a Balance

1. Most organisms are active in a limited temperature range

identify the role of enzymes in metabolism, describe their chemical composition and use a simple model to describe their specificity on substrates

    • Enzymes are biological catalysts. They lower the energy required to start a chemical reaction within a cell but do not get used up by that reaction. Every reaction and process within a cell (metabolism) is controlled by a specific enzyme.
    • Enzymes are globular proteins whose shapes are specialized so that other chemicals (substrates) can form a temporary bond with them.
    • Lock-key model is where only one small part of the enzyme molecule can form a complex with the substrate. This part of the molecule is called the active site. Only a specific substrate(s) can bond in that site and this makes the enzyme specific to that substrate.

    • The Induced fit model proposes that the active site slightly changes its shape to accommodate the substrate perfectly.

    • Pepsin – breaks down protein in stomach.
    • Lipase – breaks down fat in intestine.
    • Salivary amylase – breaks down starch in mouth.
identify the pH as a way of describing the acidity of a substance
    • pH is a scale related to the concentration of hydrogen ions in a solution.
    • A pH of 0 - 6 indicates an acid solution, a pH of 7 indicates a neutral solution and a pH of 8-14 indicates a basic solution.

explain why the maintenance of a constant internal environment is important for optimal metabolic efficiency
    • Enzymes control all the metabolic processes in the body; therefore it is important that they function at their optimum level.
    • Enzymes work most efficiently under optimal conditions. For optimal conditions to occur, organisms control body temperature, pH, enzyme/substrate concentration and the removal/absorption of water.
    • If conditions are not met, they may be denatured (active site destroyed) or reduced...