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Chapter 02 Chemistry of Life

Chapter 02 Chemistry of Life. Levels of Chemical Organization and Chemical Bonding. Define the term and describe the structure of an atom. Define the terms element, molecule, and compound. Compare and contrast the major types of chemical bonding. Lesson 2.1. Elements. Matter

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Chapter 02 Chemistry of Life

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  1. Chapter 02 Chemistry of Life

  2. Levels of Chemical Organization and Chemical Bonding Define the term and describe the structure of an atom. Define the terms element, molecule, and compound. Compare and contrast the major types of chemical bonding. Lesson 2.1

  3. Elements Matter • The substances from which the universe is made Elements • All of the different types of matter • Identified by names or chemicalsymbols • Also identified by number • Described and organized in theperiodic table 11 Sodium Na 22.99

  4. What is the symbol and number for carbon?

  5. Elements (cont.) The body’s chemical composition by weight. Living matter contains 26 of 92 natural elements. • 96% of body weight—four elements • 4% of body weight—nine elements • 0.1% of body weight—13 elements

  6. Levels of Chemical Organization Atom—smallest unit of matter Nucleus—central core of atom Proton—positively charged particle in nucleus Neutron—uncharged particle in nucleus Atomic number—number of protons in nucleus Atomic mass—number of protons and neutrons combined

  7. Atoms • Energy levels—orbital regions surrounding atomic nucleus that contain electrons • Electron—negatively charged particle • Each region has space for a specific number of electrons. • The first energy level has room for two electrons. • The second energy level has room for eight electrons. • An atom is most stable when its energy levels are filled with electrons. • Energy level increases the farther away it is from the nucleus

  8. Models of the Atom

  9. Elements (cont.) Energy Levels (cont.) • Hydrogen has only one energy level with room for one more electron. • Carbon’s first energy level is full. • Carbon’s second energy level has room for four more electrons.

  10. Isotopes and Radioactivity (cont.) Isotopes • Forms of an element that have the same atomic number but different atomic weight • Different atomic weight because of a different number of neutrons • May be stable or unstable (radioactive)

  11. Elements, Molecules, and Compounds • Element—a pure substance; made up of only one kind of atom • Molecule—a group of atoms chemically bound together in a group • Compound—substances whose molecules have more than one kind of atom

  12. Chemical Bonding • Chemical bonds form to make atoms more stable. • Atoms react with one another in ways that make their outermost energy level full. • Atoms may share electrons or donate or borrow them to become stable.

  13. Ionic Bonds • Ions form when an atom gains or loses electrons in its outer energy level to become stable • Positive ion—has lost electrons; indicated by superscript positive sign(s), as in Na+ or Ca++ • Negative ion—has gained electrons; indicated by superscript negative sign(s), as in Cl–

  14. Ionic Bonds • Ionic bonds form when positive and negative (oppositely charged) ions attract each other • Electrolyte—molecule that dissociates (breaks apart) in water to form individual ions; an ionic compound

  15. Ionic Bonding

  16. Covalent Bonds • Covalent bonds form when atoms share their outer energy ions to complete the energy level and thus become stable. • Covalent bonds do not ordinarily easilydissociate in water. • Covalent bonding is used to form all of the major organic compounds found in the body.

  17. Covalent Bonding

  18. Hydrogen Bonds • Hydrogen bonds do not create new molecules. • Hydrogen bonds weakly bond to neighboring molecules. • Hydrogen bonds are present in water, DNA, and proteins.

  19. Hydrogen Bonds

  20. Inorganic and Organic Chemistry Distinguish between organic and inorganic chemical compounds. Discuss the chemical characteristics of water. Explain the concept of pH. Discuss the structure and function of the following types of organic molecules: carbohydrate, lipid, protein, and nucleic acid. Lesson 2.2

  21. Inorganic Chemistry • Organicmolecules contain carbon-carbon covalent bonds and/or carbon-hydrogen covalent bonds; inorganic molecules do not. • Organic molecules are generally larger and more complex than inorganic molecules.

  22. Water • Water is an inorganic compound essential to life. • Water is a solvent (liquid into which solutes are dissolved), forming aqueous solutions in the body.

  23. Mixtures Mixtures-consists of two or more substances that are mixed together but not chemically bonded and each ingredient keeps its own properties

  24. Mixtures (cont.) The Importance of Water • Most abundant compound in body • Critical in all physiologic processes • Deficiency (dehydration) threatens health • Universal solvent • Stable liquid at ordinary temperatures • Participates in body’s chemical reactions

  25. Water • Water is involved in chemical reactions: • Dehydration synthesis • Hydrolysis • Chemical reactions always involve energy transfers, as when energy is used to build ATP molecules • Chemical equations show how reactants interact to form products; arrows separate the reactants from the products

  26. Water-based Chemistry

  27. Acids, Bases, and Salts Acid • A substance that releases hydrogen ions Base • A substance that releases hydroxide ions and accepts hydrogen ions Salt • A substance formed by a reaction between an acid and a base HCl  H+ + Cl− NaOH  Na+ + OH− HCl + NaOH  NaCl + H2O

  28. Acids, Bases, and Salts • Water molecules dissociate to form equal amounts of H+ (hydrogen ion) and OH– (hydroxide ion) • Acid—substance that shifts the H+/OH– balance in favor of H+; opposite of base • Base—substance that shifts the H+/OH– balance against H+; also known as an alkaline; opposite of acid

  29. Acids, Bases, and Salts (cont.) The pH Scale • Measures the relative concentrations of hydrogen and hydroxide ions in a solution. • Scale from 0 (most acidic) to 14 (most basic). • Each unit represents a 10-fold change. • Normal body fluid pH range is between 7.35 and 7.45. • Acidosis: Body fluid pH less than 7.35 • Alkalosis: Body fluid pH greater than 7.45

  30. pH • pH—Mathematical expression of relative H+ concentration in an aqueous solution • 7 is neutral (neither acid nor base) • pH values above 7 are basic; pH values below 7 are acidic

  31. pH • Neutralization occurs when acids and bases mix and form salts. • Buffers form chemical systems that absorb excess acids or bases and thus maintain a relatively stable pH (proteins, Bicarbonate, or hemoglobin).

  32. Organic Chemistry • Carbohydrates—sugars and complex carbohydrates • Contain carbon (C), hydrogen (H), and oxygen (O) • Monosaccharides—basic unit of carbohydrate molecules (for example, glucose) • Disaccharide—double sugar made up of two monosaccharide units (for example, sucrose, lactose) • Polysaccharide—complex carbohydrate made up of many monosaccharide units (for example, glycogen; stored by the body)

  33. Carbohydrates

  34. Lipids—Fats and Oils • Triglycerides • Formed by a glycerol unit and joined to three fatty acids • Store energy for later use

  35. Phospholipids • Similar to triglyceride structure, but have phosphorus-containing units—each with a head and two tails • The head attracts water (hydrophilic) and the double tail does not (hydrophobic), thus forming stable double layers (bilayers) in water • Form membranes of cells

  36. Phospholipids

  37. Cholesterol • Molecules have a steroid structure made up of multiple rings • Stabilizes the phospholipid tails in cellular membranes • Also converted into steroid hormones by the body

  38. Proteins • Very large molecules made up of amino acids held together in long, folded chains by peptide bonds • Structural proteins • Form essential structures of the body • Collagen is a fibrous protein that holds many tissues together • Keratin forms tough, waterproof fibers in the outer layer of the skin

  39. Protein

  40. Functional Proteins • Participate in chemical processes of the body • Examples include hormones, cell membrane channels and receptors, and enzymes • Enzymes—chemical catalysts • Help chemical reactions occur • Enzyme action sometimes called lock-and-key model

  41. Enzyme Action

  42. Nucleic Acids • Made up of nucleotides • A phosphate unit • A sugar (ribose or deoxyribose) • A nitrogen base (adenine, thymine or uracil, guanine, cytosine)

  43. DNA (Deoxyribonucleic Acid) • Used as the cell’s “master code” for assembling proteins • Uses deoxyribose as the sugar and A, T (not U), C, and G as bases • Forms a double helix shape

  44. DNA

  45. RNA (Ribonucleic Acid) • Used as a temporary “working copy” of a gene (portion of the DNA code) • Uses ribose as the sugar and A, U (not T), C, and G as bases

  46. ATP (Adenosine Triphosphate)

  47. Key Terms

  48. Word Anatomy (cont.)

  49. Word Anatomy (cont.)

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