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Chemistry of Life Chapter 2 How are living things (biotic) and nonliving (abiotic) things different? How are they the same? All composed of Atoms Element = substance that can’t be broken down into simpler chemical substances. 1. Represented by 1 or 2 letter code (H, O, Na, Cl, He, Ne…) 2. Made up of atoms Atoms = smallest particle of an element that has characteristics of that element. Structure of an Atom In the Nucleus: mass of the atom Protons (p+) – positive charge Neutrons (n0) – no charge (neutral) In the Electron Cloud: space of atom Electrons (e-) – negative charge; in constant motion revolving around nucleus 7 different energy levels; each can only hold a set amount of electrons IONS Atoms or group of atoms with a positive or negative charge Formed by loss or gain of electrons Combination of Substances Mixture: Physical combination of 2 or more things. Each substance keeps its original properties. Compound: Chemical combination of 2 or more elements. The substances lose their original properties and form something new. Bonding Combination of elements with electrons to become more stable Atoms want to have full outer e- level 2 e- in 1st level 8 e- in 2nd through 7th levels Covalent Bonding: Sharing of electrons between atoms example: Water (H2O) Ionic Bonding: Transferring of electrons between atoms Example: Table Salt (NaCl) Chemical Reactions forming or breaking of bonds between atoms causes substances to combine and recombine to form molecules or compounds. Occur only when conditions are right Metabolism = chemical reactions that occur over and over inside our cells Measuring Acids and Bases chemical reactions depend on how acidic or basic the environment is Indicators = pH paper, litmus, and other substances that change color pH = a measure of how acidic or basic a solution is. Scale from 0 to 14 0 = strongest acid (lots of Hydrogen ions) 7 = neutral 14 = strongest base (few hydrogen ions) ACIDS and BASES Acids: Sour taste (fruits) forms hydrogen ions (H+) in water abundance of H+ ions pH below 7, the lower the pH the stronger the acid (Strong Acid = pH 1; Weak Acid = pH 6.9) ex: HCl, H2SO4, HC2H3O2 … Bases: Bitter taste, slippery, good cleaners forms hydroxide ions (OH-) in water abundance of OH- ions Has a pH above 7, higher the pH the stronger the base (Strong base = pH 14; Weak base = pH 7.1) Ex: NaOH, NH3 … Organic Molecules Molecules involved in life HONC 1234 = rule to describe most common organic elements and their bonding patterns. H – hydrogen - 1 bond O – oxygen – 2 bonds N – Nitrogen – 3 bonds C – carbon – 4 bonds Role of Carbon in Organisms 1. 2. 3. 4. Properties of Carbon: Natures tinker toy 4 electrons in outer shell Forms 4 covalent bonds to become stable (single, double, or triple bonds) Forms chains, branched chains, and rings Image of carbon skeletons Isomers Molecules with same chemical formula, but different structural arrangements. Each has different properties Ex: Glucose and Fructose (C6H12O6) Building Blocks 50 common building blocks to carry out life’s functions Monomer – small molecule building block of life Ex: glucose Polymer – molecule formed when monomers are linked together Ex: cellulose is a polymer of glucose Condensation and Hydrolysis Reactions Condensation Reaction Chemical reaction that occurs when monomers are linked together to form polymers. Creates 1 water (H2O) molecule per link Also called synthesis or dehydration Hydrolysis Reaction Chemical reaction that occurs when polymers are broken down into monomers Addition of 1 water (H2O) for each broken link Occurs during digestion, decomposition Condensation and Hydrolysis Reactions Types of Organic Molecules Carbohydrates Lipids Proteins Nucleic Acids These 4 groups of organic molecules, their monomers, polymers, and functions, are basic and essential to biology! CARBOHYDRATES (starches and sugars) 1. 2. 3. Function – store energy for short term; sometimes used for structural support Structure Composed of C, H, and O Ratio of 2 H for every 1 O Monosaccharide – single sugar 1. Glucose (blood sugar), fructose (fruit sugar) 4. 5. Disaccharide – two sugars 1. Sucrose (table sugar – glucose + fructose) Polysaccharide – many sugars 1. Starch – storage in plants (potatoes) 2. Glycogen – storage in animal muscle and liver cells 3. Cellulose – fiber in plants (wood, paper) LIPIDS (fats, oils, waxes, steroids) Functions: 1. 2. 3. 4. Long term energy storage Insulation, cushioning of organs Waterproofing (waxes) Chemical messengers in body (steroids) Properties: 1. 2. 3. Composed of C, H, and O Much less oxygen than carbon or hydrogen 1. Beef fat = C57H110O6 Nonpolar – no net electrical charge 1. Insoluble in water Triglycerides = type of fat 1. Composed of 3 fatty acids (monomers) and 1 glycerol (sugar) 2. Saturated fat = solid at room temp, lacks double bonds between carbons. 3. Unsaturated fat = liquid at room temp (oils), at least 1 double bond between carbon atoms somewhere in fatty acid chain Triglyceride Steroids 1. 4 connected carbon ring structures 2. Used as chemical messengers in body Ex: sex hormones (testosterone and estrogen) Phospholipids 1. Composed of 2 fatty acids, glycerol, and a phosphate group 2. Major component of cell membrane A Steroid Phospholipid PROTIENS Functions: 1. 2. 3. 4. 5. Structure – hair, finger nails, skin Antibodies Hormones Movement – muscles Enzymes – proteins that speed up chemical reactions in the body 1. 10,000 types of enzymes, each has a different function Structure 1. Composed of C, H, O, N, and sometimes S 2. Made of monomers called amino acids (20 different types) 3. Amino acids consist of central carbon with the following attached 1. 2. 3. 4. 4. Hydrogen Amine group, NH2 Carboxyl group COOH R-group – What makes the A.A. different from the rest. (R can be one of 20 different groups, from a simple H to a ringed structure) Peptide Bond = covalent bond formed when amino acids link together to form proteins. Polypeptide formation NUCLEIC ACIDS (DNA and RNA) Structure 1. Composed of C, H, O, N, and P 2. Monomers = nucleotides 1. Sugar – ribose or deoxyribose 2. Phosphate group 3. Nitrogen Base – A, T, G, C, and U Function: 1. Information Storage 2. Heredity – DNA is used to pass genetic info to next generation 3. Direct cell activities – RNA directs synthesis of proteins Nucleotide Double helix Revisiting Enzymes: 28 days to digest food without enzymes, only 2-4 hours with enzymes! Catalyst - substance that speeds up chemical reactions w/o being consumed by the reaction (recycled) substrate - molecule(s) going through chemical reaction product -new molecule(s) formed after chemical reaction active site - place on enzyme where substrate fits, like a hand in a glove. substrate specific - each enzyme will only react with the substrate that fits the active site denaturation - a change in the active site so it no longer reacts with the substrate, may be caused by extremes in temperature, pH, or toxins Protein denaturation