BIOCHEMISTRY CHEMISTRY OF LIFE* • Elements: simplest form of a substance - cannot be broken down any further without changing what it is • Atom: the actual basic unit composed of protons, neutrons, and electrons THE ATOM* • Just like cells are the basic unit of life, the ATOM is the basic unit of matter. • They are very small. If placed side by side one million would stretch a distance of 1cm. • The atom is made up of 3 particles. Particle Charge PROTON + NEUTRON NEUTRAL ELECTRON - ISOTOPES* • • • atoms of the same element that HAVE A DIFFERENT NUMBER OF NEUTRONS Some isotopes are radioactive. This means that their nuclei is unstable and will break down at a CONSTANT RATE over time. There are several practical uses for radioactive isotopes: 1. CARBON DATING 2. TRACERS 3. KILL BACTERIA / CANCER CELLS COMPOUNDS* • a substance formed by the chemical combination of 2 or more elements in definite proportions – Ex: water, salt, glucose, carbon dioxide TWO TYPES OF COMPOUNDS • Organic - Contain C, H, and O in some ratio (usually referred to as chemicals of life) – • Carbohydrates, Proteins, Lipids, Nucleic Acids Inorganic - usually "support" life - no specific ratio of C, H, and O – Water (H2O), Carbon Dioxide (CO2) CHEMICAL BONDS • Chemical bonds hold the atoms in a molecule together. • There are 2 types of chemical bonds IONIC and COVALENT IONIC BONDS* • Occur when 1 or more electrons are TRANSFERRED from one atom to another. • When an atom loses an electron it is a POSITIVE charge. • When an atom gains an electron it is a NEGATIVE charge • These newly charged atoms are now called IONS – Example: NaCl (SALT) COVALENT BONDS* • Occur when electrons are SHARED by atoms. • These new structures that result from covalent bonds are called MOLECULES • ** In general, the more chemical bonds a molecule has the more energy it contains SHARING IS CARING! SOLUTION* Two parts: • SOLUTE – SUBSTANCE THAT IS BEING EVENLY DISSOLVED (SUGAR / SALT) • SOLVENT - the substance in which the solute dissolves MIXTURES* • Water is not always pure. It is often found as part of a mixture. • A mixture is a material composed of TWO OR MORE ELEMENTS OR COMPOUNDS THAT ARE PHYSICALLY MIXED – Ex: salt & pepper mixed, sugar and sand – can be easily separated WATER* • Covalently bonded compound • Due to being a polar covalent bound, can interact with a maximum 4 other water molecules through hydrogen bonding • Due to this property has very unique properties 1. Cohesion, think surface tension 2. Adhesion, capillary action, climbing up plants from soil to top of trees or water soaking paper towel • Other unique properties 1. 1-99 Celsius or 33-212 Fahrenheit in liquid state. 2. Floats when a solid ACIDS & BASES*(pH Lab) • Acids: always (almost) begin with "H" because of the excess of H+ ions (hydrogen) – Ex: lemon juice (6), stomach acid (1.5), acid rain (4.5), normal rain (6) Facts about Acids • You eat acids daily (coffee, vinegar, soda, spicy foods, etc…) ACIDS & BASES • Bases: always (almost) end with -OH because of the excess of hydroxide ions (Oxygen & Hydrogen) – EX: oven cleaner, bleach, ammonia, sea water, blood, pure water Facts about Bases • Bases turn litmus BLUE. pH SCALE* • measures degree of substance alkalinity or acidity • Ranges from 0 to 14 • 0 – 5 strong acid • 6-7 neutral • 8-14 strong base • The goal of the body is to maintain HOMEOSTASIS (neutrality) – to do this when pH is concerned, we add weak acids & bases to prevent sharp changes in pH. • These are called BUFFERS – Water – Protein – Kidneys CARBOHYDRATES* (Cereal Investigation Lab) • Living things use carbohydrates as a key source of ENERGY! • Plants use carbohydrates for structure (CELLULOSE) – include sugars and complex carbohydrates (starches) – contain the elements carbon, hydrogen, and oxygen (the hydrogen is in a 2:1 ratio to oxygen) Monosaccharides (simple sugars) • all have the formula C6 H12 O6 • all have a single ring structure – (glucose is an example) Disaccharides (double sugars) • all have the formula C12 H22 O11 • sucrose (table sugar) is an example Polysaccharides • • • • Formed of three or more simple sugar units Glycogen - animal starch stored in liver & muscles Cellulose - indigestible in humans - forms cell walls Starches - used as energy storage How are complex carbohydrates formed and broken down? Dehydration Synthesis • Combining simple molecules to form a more complex one with the removal of water – ex. monosaccharide + monosaccharide ----> disaccharide + water – (C6H12O6 + C6H12O6 ----> C12H22O11 + H2O • Polysaccharides are formed from repeated dehydration syntheses of water – They are the stored extra sugars known as starch Hydrolysis • Addition of WATER to a compound to SPLIT it into smaller subunits – (also called chemical digestion) – ex. disaccharide + H2O ---> monosaccharide + monosaccharide C12 H22 O11 + H2 O ---> C6 H12 O6 + C6 H12 O6 Lipids (Fats)* • Fats, oils, waxes, steroids* • Chiefly function in energy storage, protection, and insulation* • Contain carbon, hydrogen, and oxygen but the H:O is not in a 2:1 ratio • Tend to be large molecules -- an example of a neutral lipid is below • Neutral lipids are formed from the union of one glycerol molecule and 3 fatty acids • 3 fatty acids + glycerol ----> neutral fat (lipid) • Fats -- found chiefly in animals • Oils and waxes -- found chiefly in plants • Oils are liquid at room temperature, waxes are solids • Lipids along with proteins are key components of cell membranes • Steroids are special lipids used to build many reproductive hormones and cholesterol PROTEINS* • contain the elements carbon, hydrogen, oxygen, and nitrogen • composed of MANY amino acid subunits • It is the arrangement of the amino acid that forms the primary structure of proteins. • The structure of proteins informs of their function Major Protein Functions* • • • • Growth and repair Lower chemical reactions energy requirements (like lowering the time, or intensity of the stove fire to cook meat) Buffer -- helps keep body pH constant Energy (little amount, most come from carbohydrates) NUCLEIC ACIDS* • • • • • • • in all cells composed of NUCLEOTIDES store & transmit heredity/genetic information Nucleotides consist of 3 parts*: 1. 5-Carbon Sugar 2. Phosphate Group 3. Nitrogenous Base DNA (deoxyribonucleic acid)* • contains the genetic code of instructions that direct a cell's behavior through the synthesis of proteins • found in the chromosomes of the nucleus (and a few other organelles) RNA (ribonucleic acid)* • directs cellular protein synthesis • found in ribosomes & nucleoli CHEMICAL REACTIONS* • a process that changes one set of chemicals into another set of chemicals • REACTANTS – elements or compounds that enter into a chemical reaction • PRODUCTS – elements or compounds that are produced in a chemical reaction • Chemical reactions always involve the breaking of bonds in reactants (Hydrolysis) and the formation of new bonds in products. (Synthesis) Enzymes and Enzyme Action • catalyst: inorganic or organic substance which speeds up the rate of a chemical reaction without entering the reaction itself • Enzymes*: organic catalysts made of protein • most enzyme names end in -ase • enzymes lower the energy needed to start a chemical reaction. (activation energy) enzyme substrate (reactants) -------------> product Factors Influencing Rate of Enzyme Action * (Recall Potato Lab) 1. pH - the optimum (best) in most living things is close to 7 (neutral) • high or low pH levels usually slow enzyme activity • A few enzymes (such as gastric protease) work best at a pH of about 2.0 2. Temperature - strongly influences enzyme activity • optimum temperature for maximum enzyme function is usually about 35-40 C. • reactions proceed slowly below optimal temperatures • above 45 C most enzymes are denatured (change in their shape so the enzyme active site no longer fits with the substrate and the enzyme can't function) 3. Concentrations of Enzyme and Substrate • ** When there is a fixed amount of enzyme and an excess of substrate molecules -- the rate of reaction will increase to a point and then level off.