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Chapter 2

Chapter 2. The Chemistry of Life. 2-1: The Nature of Matter. Atoms (Basic unit of matter) Subatomic particles that make up atoms are protons, neutrons, and electrons. Subatomic particles. Bind together to form the nucleus. Protons - Neutrons - Electrons - . Positively charged (+)

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Chapter 2

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  1. Chapter 2 The Chemistry of Life

  2. 2-1: The Nature of Matter • Atoms (Basic unit of matter) • Subatomic particles that make up atoms are protons, neutrons, and electrons

  3. Subatomic particles Bind together to form the nucleus • Protons - • Neutrons - • Electrons - Positively charged (+) Not charged (neutral) Negatively charged (-) Protons Electrons Nucleus Neutrons

  4. Nonradioactive carbon-12 Nonradioactive carbon-13 Radioactive carbon-14 6 electrons 6 protons 6 neutrons 6 electrons 6 protons 7 neutrons 6 electrons 6 protons 8 neutrons Elements and Isotopes Element - a pure substance that consists of just one type of atom Isotope - atoms of the same element that differ in the number of neutrons they contain

  5. Radioactive isotopes • Can be dangerous • Can be used practically • Radioactive dating • Treat cancer • Kill bacteria

  6. Chemical Compounds / Bonds • Compound - A substance formed by the chemical combination of two or more elements in definite proportions • Ex) H2O, NaCl • Ionic Bonds - Formed when one or more electrons are transferred from one atom to another

  7. Sodium atom (Na) Chlorine atom (Cl) Sodium ion (Na+) Chloride ion (Cl-) Transfer of electron Protons +11 Electrons -11 Charge 0 Protons +17 Electrons -17 Charge 0 Protons +11 Electrons -10 Charge +1 Protons +17 Electrons -18 Charge -1 } If an atom loses an electron it becomes positive ( Na +) Ions If an atom gains an electron it becomes negative ( Cl - )

  8. 2-2: Properties of Water • Covalent Bonds - Forms when electrons are shared between atoms • Much of our planet is covered in water • Water is necessary for life to exist • If life exists on other planets, there most likely is water present • Water has many properties that make life possible

  9. Polarity (-) The oxygen atom has a stronger attraction for electrons (+) (+)

  10. Hydrogen Bonds • Because of waters partial charges, they can attract each other and create hydrogen bonds • Not as strong as covalent or ionic bonds • Waters ability to create multiple hydrogen bonds gives it many special properties

  11. Cohesion - Attraction between molecules of the samesubstance • Adhesion – Attraction between molecules of different substances

  12. Solutions and Suspensions • Mixture - Material composed of two or more elements or compounds that are physically mixed but not chemically combined • Solutions - Mixture of two or more substances in which the molecules are evenly distributed • Suspension - Mixture of water and non-dissolved materials (separate into pieces so small, they never settle out)

  13. The pH scale • Indicates the concentration of hydrogen ions in a solution • Acid - Any compound that forms H+ (hydrogen) ions in solution • Base - A compound that produces OH- (hydroxide) ions in solution

  14. Acid Neutral Base

  15. What makes carbon special? • Carbon has 4 valence electrons and can bond with various elements • Can bond with other carbons forming long chains and rings more complex and larger molecules 2- 3: Carbon Compounds Methane Acetylene Butadiene Benzene Isooctane

  16. Macromolecules “giant molecules” • Smaller units called monomers join together to form the larger macromolecules called polymers. • There are 4 groups of macromolecules • Carbohydrates • Lipids • Nucleic Acids • Proteins

  17. Starch Glucose Carbohydrates • Contain carbon (C ), hydrogen (H), and oxygen (O) atoms in a ratio of 1:2:1 [ C6H12O6 ] • Are a major source of energy • Examples include sugar, starch, monosaccharides and polysaccharides

  18. Lipids • Made mostly from C and H • Used to store energy • Not soluble in water • Examples include fats, oils, and waxes

  19. Lipid Glycerol Fatty Acids

  20. Nucleic Acids • Macromolecules containing hydrogen, oxygen, nitrogen, carbon, and phosphorus Double Helix

  21. Nucleotides • Consists of 3 parts: 5-carbon sugar, phosphate group and nitrogen base Nitrogen Base Phosphate group 5-Carbon Sugar

  22. 2 kinds of nucleic acids • RNA (ribonucleic acids) – contains sugar ribose • DNA (deoxyribonucleic acid) – contains sugar deoxyribose

  23. Proteins • Polymers made of amino acids containing H, O, C, and N • Control rates of reaction, regulate cell processes, form bones and muscles, transport substances in and out of cells, fight disease

  24. Carboxyl group General structure Alanine Serine Amino Acids

  25. More than 20 different amino acids, can join to any other amino acid • The instructions for arranging amino acids into many different proteins are stored in DNA • Each protein has a specific role • The shape of proteins can be very important

  26. Proteins Amino Acids

  27. 2- 4: Chemical Reactions and Enzymes Chemical Reactions - A process that changes or transforms one set of chemicals into another Reactants - Elements or compounds that enter into a reaction Products - Elements or compounds produced by a chemical reaction

  28. Example Reaction: Getting rid of carbon dioxide • In the blood • In the lungs CO2 + H20  H2CO3 (carbonic acid) H2CO3  CO2 + H2O Released as you breathe

  29. Energy-Releasing Reaction Energy-Absorbing Reaction Activation energy Products Activation energy Reactants Reactants Products Energy in reactions

  30. Activation Energy • The energy that is needed to get a reaction started

  31. Catalysts – are chemicals that speed up a chemical reaction by lowering activation energy • Enzymes: • Biological catalysts (proteins) • Speed up reactions in cells • Very specific • Named for the reaction is catylzes • Enzyme names always end in -ase • Substrates: • The reactants of enzyme catalyzed reactions • The active site of the enzyme and the substrate have complementary shapes • Fit like a lock and key

  32. Enzyme Action Enzyme – substrate complex

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