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CHAPTER 6 The Chemistry of Life Atoms & Their Interactions • elements - make up earth & organisms (O, C, H, N, S, P, K, Si, Al, Fe, Ca) –cannot be broken down by a chemical process into a simpler substance Atoms & Their Interactions Natural elements in living things 114 elements in all Only 25 are essential to living things Carbon(C), Hydrogen(H), Oxygen(O), and Nitrogen(N) make up 96% of human body Trace elements – elements found in living things in very small amounts Atoms & Their Interactions •Atoms - smallest particle of an element that has the elements properties Atoms & Their Interactions Structure of an atom protons (+) = Atomic number neutrons (no charge) electrons (-) Atoms & Their Interactions Electron Energy Levels – electrons exist around a nucleus in energy levels 1st level – 2 electrons 2nd level – 8 electrons 3rd level – 18 electrons 12 18 17 8 34 7 56 1 6 1 15 16 2 13 14 3 7 58 2 9 4 10 11 12 7 N 14.0067 Nitrogen Atoms & Their Interactions Atoms that contain equal amounts of protons and electrons have a neutral charge. Isotopes: atoms of the same element that have a different number of neutrons Ex. Carbon-12 6p+ & 6n0 Carbon-14 6p+ & 8n0 Atoms & Their Interactions Isotopes - have an unstable nucleus that breaks apart giving off energy in the form of radiation used to tell age of fossils preserve food treat cancer Atoms & Their Interactions Compound: atoms of 2 or more different elements that are chemically combined Ex. NaCl – salt H2O - water Atoms & Their Interactions Covalent Bond: chemical bond formed when two atoms share electrons Ex. H2 Molecule: group of atoms held together by covalent bonds No overall charge Ex. H2O Atoms & Their Interactions Electrons shared in a chemical bond (each atom donates one electron) Outer energy level in both elements is full (stable) Double covalent bonds have four electrons Triple covalent bonds have six electrons Atoms & Their Interactions Atoms & Their Interactions Ion: an atom that gains or loses electrons Ionic Bond: attractive force between two ions of opposite charge Electrons are lost by one element and gained by another Outer energy level in both elements is full (stable) Atoms & Their Interactions Atoms & Their Interactions Chemical Reactions Occur when bonds are formed or broken Substances recombine into different substances In organisms, reactions occur inside cells Metabolism = all of the chemical reactions that occur within an organism Atoms & Their Interactions Chemical Reactions Reactants: substances that undergo chemical reactions Products: substances formed by chemical Reactants Products reactions Atoms are neither created or destroyed in a chemical reaction … they are simply rearranged Atoms & Their Interactions Mixtures Combination of substances in which individual components retain their own properties Components do not combine chemically Ex. Sand & sugar mixture Atoms & Their Interactions Solutions Mixture in which one or more substances (solutes) are distributed evenly in another substance (solvent) One dissolved in another Ex. Kool-aid Concentration: amount of solute dissolved in solvent Organisms can’t survive unless concentrations stay within a specific narrow range Atoms & Their Interactions Acids & Bases Chemical reactions in organisms depend on pH of the environment pH is the measure of how acidic or basic a solution is Scale 0-14 acid: 0 to < 7 bases: > 7 to 14 Atoms & Their Interactions Acids - - release hydrogen ions (H+) in water Ex. HCl (hydrochloric acid) Bases - - produce hydroxide ions (OH-) in water Ex. NaOH (sodium hydroxide) 6.2 Water & Diffusion Why is Water Important? Life process Transport materials Makes up 70-95% of most organisms MOST IMPORTANT COMPOUND IN LIVING ORGANISMS 6.2 Water & Diffusion What is a polar molecule? POLAR BOND: atoms in a covalent bond do not share electrons equally POLAR MOLECULE: molecule with an unequal distribution of charge Molecule has a positive end and a negative end Positively charged end Negatively charged end 6.2 Water & Diffusion Water is a polar molecule. Shared electrons spend more time near the oxygen nucleus that near the Hydrogen nucleus Attracts other polar molecules Can dissolve many ionic compounds (salt) and other polar molecules (sugar) Attracts other water molecules 6.2 Water & Diffusion What is a Hydrogen Bond? Positively charged hydrogen atom of one water molecule attract the negatively charged oxygen atom of another water molecule = weak hydrogen bond IMPORTANCE: Helps hold biomolecules together (proteins) Creeps up thin tubes (capillary action in plants) 6.2 Water & Diffusion Water resists temperature change. Requires more heat to increases temperature Loses a lot of heat when cools Acts as an insulator to help maintain steady environment Helps cells maintain Homeostasis 6.2 Water & Diffusion What is Diffusion? Net movement of particles from an area of higher concentration to an area of lower concentration 6.2 Water & Diffusion What affects the rate of diffusion? Concentration Temperature Pressure 6.2 Water & Diffusion How does concentration affect diffusion? Primary controlling factor More concentrated = faster diffusion (more collisions) How does temperature affect diffusion? Increase temperature = increase in energy Particles move faster = faster rate of diffusion How does pressure affect diffusion? Increase pressure accelerates particle motion which increases rate of diffusion 6.2 Water & Diffusion What is the result of Diffusion? Particles become evenly distributed Motion and collisions still occur but no further change in concentration Dynamic Equilibrium 6.2 Water & Diffusion What is the Concentration Gradient? Concentration Gradient: difference in concentration of substance across space ions and molecules move with concentration gradient From higher concentration to lower concentration Diffusion will occur until there is no longer a concentration gradient 6.2 Water & Diffusion What does diffusion have to do with living organisms? Diffusion is one way cells move substances in and out of the cell Material moving out of cell equals material moving into cell 6.3 Life Substances Organisms are made up of organic compounds. ☞All organic compounds contain Carbon (C) ☞To be stable, a carbon atom forms 4 covalent bonds 6.3 Life Substances Ways a Carbon Atom Bonds: ☞When 2 carbon atoms form covalent bonds they can share 1, 2 or 3 electron pairs ☞Single Bond – share 1 pair electron ☞Double bond – share 2 pairs electrons ☞Triple Bond – share 3 pairs electrons 6.3 Life Substances Shape of bonded carbon atoms can vary. ☞Straight Chains ☞Branched chains ☞Ring The many different ways of bonding lead to large number of carbon structure possibilities. 6.3 Life Substances What is an Isomer? ☞Compounds with same chemical formula but different 3D structure ☞ Ex: Glucose (C6H12O6) & fructose (C6H12O6) Fructose Glucose 6.3 Life Substances What are macromolecules ? ☞Large organic compounds ☞Cells build biomolecules by bonding small molecules together to form polymers ☞Four main macromolecules ☞Carbohydrates ☞Lipids ☞Proteins ☞Nucleic Acids 6.3 Life Substances Carbohydrates = ENERGY ☞Composed of C, H, O ☞Monosaccharides – simple sugars ☞Ex. Glucose –found in some fruits (less sweet) ☞ Fructose – honey (more sweet) ☞Dissacharides - formed from 2 monosac. ☞Ex. Sucrose – table sugar 6.3 Life Substances ☞Polysaccharides – formed from many monosaccharide subunits ☞Starch – energy storage of plants ☞Gylcogen – energy stored in liver of mammals ☞Cellulose – cell wall of plants 6.3 Life Substances Lipids = INSULATION / PROTECTION ☞Insoluble in water because nonpolar molecule ☞Examples: fats, oils, waxes, steroids ☞Importance to organisms ☞Some energy storage ☞Insulation ☞Protective covering ☞Major components of membranes that surround all living cells 6.3 Life Substances Proteins = STRUCTURE ☞Made up of amino acids – building blocks of proteins ☞20 Amino Acids ☞Held together by peptide bonds 6.3 Life Substances Proteins come in many shapes & sizes. ☞ # of amino acids and how they interact determines 3D shape and twist of protein ☞Shape is important in function of protein in a cell ☞If amino acid sequence changes, shape of protein changes and it won’t function properly 6.3 Life Substances Importance of proteins ☞Functions of body systems ☞Muscle contraction ☞Transporting oxygen in the blood ☞Provide immunity ☞Regulate other proteins ☞Chemical reactions 6.3 Life Substances Enzymes – protein that changes rate of a chemical reaction 6.3 Life Substances Action of enzymes: 1. Substrate fits into enzyme active site (lock & key) 2. Enzyme alters substrate shape 3. Products are released 4. Enzyme ready to act on more substrate 6.3 Life Substances Nucleic Acids = CODE OF CELL INFORMATION ☞Complex macromolecules that stores cellular information ☞Made up of nucleotides ☞Examples: DNA & RNA MACROMOLECULES SUMMARY Macromolecule subunits Carbohydrates monosacchari des function examples Energy storage Starch Gylcogen, cellulose MACROMOLECULES SUMMARY macromolecule subunits function examples Carbohydrates monosaccharid es Energy storage Starch Gylcogen, cellulose Lipids Gylcerol Fatty acids Energy storage insulation Animal fat Vegetable oil MACROMOLECULES SUMMARY macromolecule subunits Carbohydrate monosacchar s ides Lipids Gylcerol Fatty acids Proteins Amino acids function examples Energy storage Starch Gylcogen, cellulose Energy storage insulation Structure enzymes Animal fat Vegetable oil Muscle protein immunity MACROMOLECULES SUMMARY macromolecule subunits Carbohydrates monosaccharid es function examples Energy storage Starch Gylcogen, cellulose Lipids Gylcerol Fatty acids Energy storage insulation Animal fat Vegetable oil Proteins Amino acids Structure enzymes Muscle protein immunity Nucleic Acids nucleotides Store information DNA RNA