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By: Mrs. Bailey Biology Content Standards 1. The Chemistry of Life Broad Concept: Chemical elements form organic molecules that interact to perform the basic functions of life. 1.1 Recognize that biological organisms are composed primarily of very few elements. The six most common are C, H, N, O, P, S. 1.2 Describe the basic molecular structures and primary functions of the four major categories of organic molecules (carbohydrates, lipids, proteins, and nucleic acids). 1.3 Explain the role of enzymes as catalysts that lower the activation energy of biochemical reactions. Identify factors, such as pH and temperature, which have an effect on enzymes. Atoms are the smallest particle into which an element can be divided. Isotopes differ from each other in the number of neutrons, not in the number of protons. Ionic bonds are formed when atoms become ions by gaining or losing electrons. Covalent bonds form when atoms share electrons. A. Water covers more than 75% of the Earth’s surface. It is the most abundant compound in nearly all living things! B. Water is able to dissolve 1000’s of substances because it is POLAR - slightly charged on each end. This results in the property of COHESION Water is “sticky” Cohesion Surface Tension CAPILLARITY ADHESION Attraction of water to solids Water is the “universal” solvent ! MIXTURE - a substance made up of 2 or more elements or compounds that are mixed together but not chemically combined. Living things are in part composed of mixtures involving water. MIXTURE Solution Suspension A mixture in which one or more substances are evenly spread out in another substance A mixture of water and non-dissolved material. Examples: Salt water, sugar water, plasma Examples: Dirt and water, Italian salad dressing, blood Solution = Solute + Solvent Dissolve the solute in the solvent! Acid - compound that releases hydrogen ions (H ) + into solution. pH: 1-6 Citric acid pH = 2 HCl pH = 1 Ascorbic acid pH = 3 Base - compound that releases hydroxide ions (OH ) - into solution. pH: 8-14 pH = 11 pH = 9 pH scale is from 0-14 A buffer is a solution that can maintain a nearly constant pH when diluted, or when strong acids or bases are added. A. INORGANIC COMPOUNDS Compounds that do not contain carbon Examples: Water, Minerals (Calcium phosphate/ bone) Exception is CO2 B. ORGANIC COMPOUNDS Compounds that DO contain carbon (except CO2) Examples: Sugars, Fats, Proteins, DNA 6 Most Common Elements in Organic Molecules! I definitely need to know this! is special! • Forms covalent bonds that are strong and stable. • Can form 4 single covalent bonds. • Can also form double bonds, triple bonds, chains, and rings! Remember: A covalent bond is formed by 2 shared electrons! C. Poly = many mer = unit à Polymer = many units. A polymer has a repeating structure, usually based on a carbon backbone. The repeating structure results in large chainlike molecules. a “monomer” a “polymer” A macromolecule is a giant polymer! 4 Major Categories of Organic Compounds • Carbohydrates • Lipids • Proteins • Nucleic Acids • General formula is C(H2O)n • Sugars, starches, cellulose • High Energy! Mono-saccharide Contains 1 saccharide molecule Di-saccharide Contains 2 saccharide molecules Poly-saccharide Contains many saccharide molecule • Glucose the sugar green plants produce • Galactose found in milk • Fructose found in fruits (sweetest) C6H12O6 C6H12O6 C6H12O6 C6H12O6 R is a carbon group, such as -CH3 Glucose Fructose 6 5 1 4 3 2 OH is down … α- Glucose β- OH is up … • Maltose Malt sugar (glucose + glucose) • Lactose Milk sugar (glucose + galactose) • Sucrose Common table sugar (glucose +fructose) NOTE: A molecule of water is lost! Maltose + Lactose NOTE: A molecule of water is lost! Sucrose Largest carbohydrate (may consist of 1000s of monosaccharides) • Starch Plants store excess sugar in this form inside of leucoplasts. • Glycogen Animals store excess sugar in this form … liver and muscles. • Cellulose Gives strength and rigidity to plant cell walls. All are polymers of glucose! Starch grains in a bean embryo. Why so many? Glycogen is stored in liver and muscle cells! Muscle cells Liver cells Cellulose Starch … made up of α-glucose Cellulose … made up of β-glucose. Toughness is due to the arrangement of glucose units in the polymer chain and the hydrogen-bonding between neighboring chains. • The joining of 2 or more monomers to form a larger polymer. • When the bond is complete, a molecule of water is released from the 2 monomers. EXAMPLE: The joining of glucose and fructose to form sucrose. • A polymer is split apart to again form monomers. • A water molecule is taken in by the chemical reaction. EXAMPLE: The splitting of sucrose into glucose and fructose. or … maltose into glucose and glucose! • Fats, oils, and waxes. • Lipids are compounds made up of C, H, and O, but often P and N. • Many lipids are formed by the attachment of two or three fatty acids to glycerol (an organic alcohol). fatty acid fatty acid glycerol fatty acid Because of the kinks in the hydrocarbon tails, unsaturated fats can’t pack as closely together, making them liquid at room temperature. Lipids: 3 major roles in living things 1. Store energy 2. Form biological membranes. 3. Some hormones are lipids. Seal pup has blubber. Unlike other organic compounds, lipids do not Oil dissolve in water! Why would that be very important in living things? Water Types of Lipids (based on structure) • Triglyceride - 3 fatty acids + glycerol • Phospholipid - 2 fatty acids + glycerol • Wax - long fatty acid chain + a long alcohol chain. • Steroid - composed of 4 carbon rings Found in substances as varied as hormones, nerve tissue, toad venoms, and plant poisons. Cholesterol To be specific, it is a sterol or a steroid with an –OH group • Cholesterol is an important part of many cells such as nerve cells. • However, excessive cholesterol in the diet is a risk factor for heart disease. Here we go again … • Organic compounds composed mainly of C, H, O, and N. • Proteins are polymers of together by peptide AMINO ACIDS , joined bonds. • All amino acids have a similar chemical structure, but differ in a region of the molecule known as an R group. (Variable group) (Amino group) (Carboxyl group) The amino acid, phenylalanine, is found in the sweetener aspartame. Infants born with w/PKU cannot break down phenylalanine. The buildup can retard normal brain development. Here we go again … PROTEINS 2° 1° 3° 4° Proteins have MANY ROLES! • Help carry out chemical reactions by serving as enzymes. • Pump small molecules in/out of cells by serving as permeases. • Serve as chemical messengers called hormones. • Used in forming disease–fighting antibodies. • Provides energy if carbohydrate and fat are in short supply. • Play a structural role – cytoskeleton - The skin and muscles of animals are made mostly of proteins. • Biological catalysts (speed up reactions by lowering activation energy , but remain themselves unaffected) • Most enzymes are proteins. • Active Site - a special place on the enzyme where chemical bonds form between enzyme and substrate. • Work within an optimal range of pH and temperature. Enzymes lower activation energy (EA)! Substrate Substrate Products Substrates Product Temperature increase speeds up enzyme controlled reactions, but only to a point. When heated too much, enzymes (since they are proteins dependent on their shape) become denatured. Changes in pH will also denature the enzyme by changing the shape of the enzyme. Enzymes are also adapted to operate at a specific pH or pH range. (mouth) (stomach) (kidney) • Very large and complex organic molecules that store important information in the cell. • Polymers of nucleotides. • There are 2 Basic Kinds: DNA and RNA. 1. 2. 4. 3. Biology Content Standards 1. The Chemistry of Life Broad Concept: Chemical elements form organic molecules that interact to perform the basic functions of life. 1.1 Recognize that biological organisms are composed primarily of very few elements. The six most common are C, H, N, O, P, S. 1.2 Describe the basic molecular structures and primary functions of the four major categories of organic molecules (carbohydrates, lipids, proteins, and nucleic acids). 1.3 Explain the role of enzymes as catalysts that lower the activation energy of biochemical reactions. Identify factors, such as pH and temperature, which have an effect on enzymes.