Biological Molecules

• Most of the molecules in living organisms fall into three categories: carbohydrates, proteins and lipids.
• Carbohydrates contain the elements carbon, hydrogen and oxygen.
• A monosaccharide is a simple sugar such as glucose or fructose.
• S - We will control the concentration and volume of the amylase, iodine and starch solution used in the investigation
• M1 - We will measure the time taken for the iodine to stop turning black
• All contain carbon and so are described as organic molecules.
• R - We will repeat the investigation several times to ensure reliability
• Glucose molecules contain lots of energy which can be released in respiration by breaking the bonds between the carbon atoms.
• A disaccharide is made when two monosaccharides join together.
• Maltose is formed from two glucose molecules.
• Sucrose is formed from one glucose and one fructose molecule.
• A polysaccharide is formed when lots of monosaccharides join together.
• Starch, glycogen or cellulose are all formed when lots of glucose molecules join together.
• Polysaccharides are insoluble and therefore useful as storage molecules.
• Glycogen, cellulose and starch are all made from glucose molecules.
• Most fats (lipids) in the body are made up of triglycerides.
• The basic unit of a triglyceride is one glycerol molecule chemically bonded to three fatty acid chains.
• The fatty acids vary in size and structure.
• Lipids are divided into fats (solids at room temperature) and oils (liquids at room temperature).
• Biuret solution contains copper (II) sulfate which is dangerous particularly if it gets in the eyes, so always wear goggles.
• When an enzyme and its complementary substrate randomly collide an enzyme-substrate complex forms, and the reaction occurs.
• Sodium hydroxide in biuret solution is corrosive, if any chemicals get onto your skin wash your hands immediately.
• When working with practical investigations, remember to consider your CORMS evaluation.
• When the substrate moves into the enzyme’s active site they become known as the enzyme-substrate complex.
• After the reaction has occurred, the products leave the enzyme’s active site as they no longer fit it and it is free to take up another substrate.
• Iodine is also an irritant to the eyes.
• The enzyme is unchanged and will go on to catalyse further reactions.
• Enzymes are affected by temperature; a change in temperature can alter the rate of a chemical reaction.
• Ethanol is highly flammable; keep it away from any Bunsen burner.
• A product (or products) forms from the substrate(s) which are then released from the active site.
• Enzymes are proteins that act as biological catalysts to speed up the rate of a chemical reaction without being changed or used up in the reaction.
• Enzymes and substrates randomly move about in solution.
• Enzymes are necessary to all living organisms as they maintain reaction speeds of all metabolic reactions at a rate that can sustain life.
• The Bunsen burner itself is a hazard due to the open flame.
• Enzymes are specific to one particular substrate(s) as the active site of the enzyme, where the substrate attaches, is a complementary shape to the substrate.
• If we did not produce digestive enzymes, it would take around 2 - 3 weeks to digest one meal; with enzymes, it takes around 4 hours.
• Proteins are formed from long chains of amino acids.
• There are 20 different amino acids.
• When amino acids are joined together a protein is formed.
• Amino acids can be arranged in any order, resulting in hundreds of thousands of different proteins.