Chapter 2 The Chemistry of Life

2.1 The nature of matter Atom: the smallest particle of an element that has the properties of that element Atom is made of three subatomic particles: Proton * Positive, nucleus Electron * Negative, outside nucleus in energy levels First energy level -- 2e Second energy level -- 8e Third energy level -- 18e Neutron * No charge, nucleus

                                                                                                                                                                                                                                                                                                                                 

Number of protons usually is equal to the number of electrons so that the overall charge of an atom is neutral!!  If atoms of the same element have different number of neutrons, they are called isotopes! EX. C - 12 , C - 13, C - 14 When two or more atoms of different elements are chemically combined you create what is called a compound. EX. Water

Compounds can be made with three different kinds of bonds: Covalent Share electrons to be stable Strongest and most common bond Molecule: group of atoms held together with covalent bonds with no overall charge Van der Waals forces (what holds molecules together)

Ionic Hydrogen Gain / lose electrons to be stable Ion: a charged particle Less abundant in living things than covalent bonds Hydrogen

Mixtures & Solutions Mixture: a combination of substances in which the individual components retain their own properties  Solution: a mixture in which one or more substances are distributed evenly in another substance Two parts to every solution: Solute --- What is being dissolved Solvent -- What is doing the dissolving * Most common... WATER

pH pH: a measure of how acidic or basic a solution is Acid: substance that forms H+ ions in water 0 - 7 Base: substance that forms OH- ions in water 7 – 14

Acids & Bases Acids Bases Higher concentration of H+ ions pH value less than 7 Sour taste React with metals Blue litmus paper will turn red if an object is an acid Lower concentration of H+ ions pH value more than 7 Bitter taste Slippery Turn red litmus paper blue if an object is a base

2.2 Water and Diffusion Perhaps the most important compound in living organisms is water! Properties of water: Polarity Has a positive and negative end Gives water its dissolving property Resists Temperature Changes Water expands when it freezes Adhesion  Graduated cylinder Adhesion is greater between glass & water than water & water!

2.3 Carbon Compounds The one element that defines living organisms is Carbon! Carbon has four electrons in its outermost shell; therefore, it can combine with almost every other element Any compound that contains carbon is considered to be an organic compound! If it does not contain carbon it is inorganic.

Four types of Organic compounds: Carbohydrates: Made of C, H, O (C to H ration is 2 to 1) Monomer: monosaccharide Function: Provide quick energy EX. Glucose: how animals store food Starch: how plants store food Cellulose: composes cell walls of plants

2) Lipids Made of C, H, O --- (C to H ratio higher than 2 to 1) Monomer: Glycerol & 3 fatty acids Function: 1) Store energy 2) Insulation 3) Protection EX. Fats and Oils

3) Proteins Made of C, H, O, N, Sulfur Monomer: Amino Acid 20 AA Function: 1) Build Muscle 2)Transportation (blood -- hemoglobin) 3) Speed up chemical reactions (enzymes)

4) Nucleic Acids Made of C, H, O, N, Phosphorus Monomer: Nucleotide Function: Store genetic information EX. DNA (Deoxyribose Nucleic Acid) – Master RNA (Ribose Nucleic Acid) -- Copy of DNA

2.4 Chemical Reactions and Enzymes Chemical reaction = changes one set of chemicals into another set of chemicals Chemical reactions have two parts: Reactants Products CO2 + H2O  H2CO3 Reactants Product

Enzymes Enzymes are proteins that act as a biological catalyst. Catalyst: a substance that speeds up the rate of chemical reaction Enzymes speed up chemical reactions that take place in the cell.

Enzyme Action The enzyme-substrate complex Enzymes are substrate specific. They act like a lock and key. Enzymes will only catalyze their substrates. Regulation of Enzyme Activity Enzymes can be affected by: Heat pH Concentration of Substrate Proteins that turn enzymes “on” and “off”

Example of what an enzyme does! How enzymes work Potato + Peroxide  water + oxygen (catalase)

Where are enzymes? Enzymes regulate many chemical reactions such as: Photosynthesis Cellular respiration Digestion Enzymes are reusable Once they work with one substrate they release and go to another substrate.