Year 12 PES Biology Notes The Chemistry of Life M6 Polysaccharides and lipids are important macromolecules in cells. M5 The three-dimensional structure of a protein is critical to its function.. M1 The chemical unit of genetic information in most organisms is DNA.
Introduction All matter is made up of atoms. Substances consisting of one sort of atom are called elements 92 naturally occurring elements eg H - Hydrogen, C- Carbon, N - Nitrogen
Atoms can join together to form compounds eg Water (H2O) is very different from Hydrogen and Oxygen. New substances can be made when we join atoms together. The proportions of those atoms are important. eg H 2 O 2 (Hydrogen peroxide - bleach) is very different from H 2 O O H H H 2 O
Chemists divided all compounds into two main types: Organic and Inorganic Generally organic compounds are 1. produced by living things 2. contain carbon (except CO2) and 3. are complex.
Four major types of organic compounds found in living things: Carbohydrates: for example Glucose Sucrose [Key: Grey - Hydrogen, Red - Oxygen, Green - Carbon]
Four major types of organic compounds found in living things: Lipids eg oils, fats. Each compound is made up of a unit of Glycerol and three units of Fatty Acids Glycerol Fatty Acid Fatty Acid Fatty Acid
Four major types of organic compounds found in living things: Proteins eg enzymes, structural proteins
Four major types of organic compounds found in living things: Nucleic Acids eg DNA, RNA
Major Carbohydrates Made up of Carbon, Hydrogen and Oxygen (CHO) 1) Monosaccharides (single sugar) - basic component of most carbohydrates - used as a source of energy when converted to glucose. Examples include glucose, fructose, lactose, (note ending in "-ose")
Major Carbohydrates 2) Disaccharides (double sugars) Examples include sugar (sucrose) maltose Soluble and plants use it to transfer food from leaves to roots, seeds, fruit.
Major Carbohydrates 3) Polysaccharides (many sugars) Generally insoluble and use for storage of energy Examples include starch (in plants), glycogen (in animals), cellulose (fibre)
Major Lipids Similar to carbohydrates in structure but fewer oxygen molecules. Fats - solids at room temperature, generally come from animals Oils - liquids at room temperature, generally come from plants
Major Lipids Examples in cells include: Lipid bi-layer in cell membrane
Major Lipids Other examples in cells include: Hormones are mainly lipids Cholesterol is a lipid Lipids can be used for energy storage and insulation in higher animals.
Energy storage: lipids vs carbohydrates - Energy stored in lipids is twice as much as that stored in the same weight of carbohydrates. - When food is stored as lipids, it does not interfere in the water balance, so fewer problems with osmosis - Polysaccharides are easier to convert to simple sugars eg glucose - This is the main source of intermediate energy in cells - In plants starch is converted to glucose - In animals glycogen is converted to glucose.
Proteins - Made up of one or more polypeptide chains - the chains are made up of many different amino acids - 20 different amino acids - therefore the number of different proteins is limitless
7 major functions of proteins: - Structure - Catalytic (Enzymes) - Contraction (eg muscles) - Transport - Defence (antibodies) - Coordination (hormones) - Storage
Stages of development of protein structure - String of amino acids is formed - Coiling and folding of parts of the chain occurs - Final folding of whole chain to form 3D shape - Two or more proteins fold together to produce final molecule - Examples: complex protein - haemoglobin simple protein - insulin
Nucleic Acids - Example is DNA - used to store information about what the cell has to do - Discovered in 1953 - Able to copy itself (self-replicate) and pass information on to daughter cells - Made up of numerous nucleotides - Each nucleotide is made up of a sugar (ribose), a phosphate group and a base
- Two types of nucleotides: DNA and RNA - 5 types of bases Four found in DNA - Adenine (A), Thymine (T), Guanine (G) and Cytosine (C)
- Two types of nucleotides: DNA and RNA - Four bases found in RNA Adenine Guanine Cytosine also Uracil (U) (Note: Not Thymine]