Chapter 2 Chemical Basis of Life

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Chapter 2 Chemical Basis of Life

  1. 1. Chapter 2 LecturePowerPoint Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
  2. 2. Paris Junior College 2401Anatomy and Physiology I Chapter 2 Susan Gossett sgossett@parisjc.edu Department of Biology 2
  3. 3. Hole’s Human Anatomy and Physiology Twelfth Edition Shier w Butler w Lewis Chapter 2 Chemical Basis of LifeCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 3
  4. 4. 2.1: Introduction Why study chemistry in an Anatomy and Physiology class?- Body functions depend on cellular functions- Cellular functions result from chemical changes- Biochemistry helps to explain physiological processes 4
  5. 5. 2.2: Structure of MatterMatter – anything that takes up space and has mass (weight).It is composed of elements.Elements – composed of chemically identical atoms: • Bulk elements – required by the body in large amounts • Trace elements - required by the body in small amounts • Ultratrace elements – required by the body in very minute amountsAtoms – smallest particle of an element 5
  6. 6. Table 2.1 Some Particles of Matter 6
  7. 7. Elements and Atoms• All matter is composed of elements• Elements are the parts of compounds• Elements are: • Bulk elements • Trace elements • Ultratrace elements• The smallest parts of atoms are elements 7
  8. 8. Atomic Structure Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.Atoms - composed of Neutronsubatomic particles: (n0) - • Proton – carries a single positive charge Proton • Neutron – carries no (p+) electrical charge + 0 Electron • Electron – carries a single + 0 - (e–) negative charge 0 0 +Nucleus • Central part of atom • Composed of protons and neutrons Nucleus • Electrons move around the - nucleus 8 Lithium (Li)
  9. 9. Atomic Number, Mass Number and Atomic WeightAtomic Number • Number of protons in the nucleus of one atom • Each element has a unique atomic number • Equals the number of electrons in the atomMass Number • The number of protons plus the number of neutrons in one atom • Electrons do not contribute to the weight of the atomAtomic Weight • Average of mass numbers of the isotopes of an element 9
  10. 10. IsotopesIsotopes • Atoms with the same atomic numbers but with different mass numbers • Different number of neutrons • Oxygen often forms isotopes (O16, O17, and O18) 10
  11. 11. Molecules and CompoundsMolecule – particle formed when two or more atomschemically combineCompound – particle formed when two or more atoms ofdifferent elements chemically combineMolecular formulas – depict the elements present andthe number of each atom present in the molecule H2 C6H12O6 H2O 11
  12. 12. Bonding of Atoms• Bonds form when atoms combine with other atoms• Electrons of an atom occupy regions of space calledelectron shells which circle the nucleus• For atoms with atomic numbers of 18 or less, the followingrules apply: • The first shell can hold up to 2 electrons • The second shell can hold up to 8 electrons • The third shell can hold up to 8 electrons 12
  13. 13. 2.1 From Science to Technology Radioactive Isotopes Reveal Physiology 13
  14. 14. 2.2 From Science to Technology Ionizing Radiation: From the Cold War to Yucca Mountain 14
  15. 15. Bonding of Atoms • Lower shells are filled first Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. • If the outermost shell is full, the atom is stable - - - + + 0 + 0 0 + - 0 0 + 0 + - -Hydrogen (H) Helium (He) Lithium (Li) 15
  16. 16. Bonding of Atoms: IonsIon• An atom that gains or loses electrons to become stable• An electrically charged atomCation• A positively charged ion 11p+ 12n0 17p+ 18n0• Formed when an atom loses electronsAnion Sodium atom (Na) Chlorine atom (Cl)• A negatively charged ion• Formed when an atom gainselectrons 16
  17. 17. Ionic Bonds Ionic Bonds • An attraction between a cation and an anion • Formed when electrons are transferred from one atom to another atom Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Na+ Cl–+ 11p+ 12n0 17p+ 18n0 – Sodium ion (Na+) Chloride ion (Cl–) Sodium chloride 17
  18. 18. Covalent Bonds • Formed when atoms share electrons Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. H H H2 - - - + + + + -Hydrogen atom + Hydrogen atom Hydrogen molecule • Hydrogen atoms form single bonds H―H • Oxygen atoms form two bonds O=O • Nitrogen atoms form three bonds N≡N • Carbon atoms form four bonds O=C=O 18
  19. 19. Bonding of Atoms: Structural Formula • Structural formulas show how atoms bond and are arranged in various molecules Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. H HH H O O O O C O H2 O2 H2O CO2 19
  20. 20. Bonding of Atoms: Polar MoleculesPolar Molecules • Molecule with a slightly negative end and a slightly positive end • Results when electrons are not shared equally in covalent bonds • Water is an important polar molecule Slightly negative ends 20 (a) Slightly positive ends
  21. 21. Hydrogen BondsHydrogen Bonds • A weak attraction between the positive end of one polar molecule and the negative end of another polar molecule • Formed between water molecules • Important for protein and nucleic acid structure H H O H Hydrogen bonds O H H O H H O H H O 21 H (b)
  22. 22. Chemical ReactionsChemical reactions occur when chemical bonds form orbreak among atoms, ions, or moleculesReactants are the starting materials of the reaction - theatoms, ions, or moleculesProducts are substances formed at the end of the chemicalreaction NaCl  Na+ + Cl- Reactant Products 22
  23. 23. Types of Chemical ReactionsSynthesis Reaction – more complex chemical structureis formed A + B  ABDecomposition Reaction – chemical bonds are broken to forma simpler chemical structure AB  A + BExchange Reaction – chemical bonds are broken and newbonds are formed AB + CD  AD + CBReversible Reaction – the products can change back to thereactants A + B n AB 23
  24. 24. Acids, Bases, and SaltsElectrolytes – substances that release ions in water NaCl  Na+ + Cl-Acids – electrolytes that dissociate to release hydrogen ionsin water HCl  H+ + Cl-Bases – substances that release ions that can combine withhydrogen ions NaOH  Na+ + OH-Salts – electrolytes formed by the reaction between anacid and a base HCl + NaOH  H2O + NaCl 24
  25. 25. Acid and Base ConcentrationpH scale - indicates the concentration of hydrogen ions insolutionNeutral – pH 7; Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.indicates equal Relative Acidic + 6.6 7.4 8.4 Sodium Amounts H cow’s Human biocarbonateconcentrations of H+ of H+ (red) and OH– 3.0 4.2 tomato 5.3 cabbage milk blood 11.5 2.0 apple 10.5and OH- (blue) gastric juice juice juice 8.0 milk of magnesia Household ammonia 7.0 Egg 6.0Acidic – pH less than Distilled white Basic corn water OH– pH 0 1 2 3 4 5 6 7 8 9 10 11 12 13 147; indicates a greater Acidic H+ concentration increases Neutral OH– concentration increases Basic (alkaline)concentration of H+Basic or alkaline – pH greater than 7;indicates a greater concentration of OH- 25
  26. 26. Neutralization and Buffers• Neutralization occurs when an acid and base react to form a salt and water in a displacement reaction. – HCl + NaOH  NaCl + H2O – Termed neutralization because water is formed neutralizing the solution.• Buffers act as acids when pH is high and bases when pH is low. – Carbonic acid-bicarbonate system.
  27. 27. 2.3: Chemical Constituents of Cells Organic v. Inorganic MoleculesOrganic molecules • Contain C and H • Usually larger than inorganic molecules • Dissolve in water and organic liquids • Carbohydrates, proteins, lipids, and nucleic acidsInorganic molecules • Generally do not contain C and H • Usually smaller than organic molecules • Usually dissociate in water, forming ions • Water, oxygen, carbon dioxide, and inorganic salts 27
  28. 28. Inorganic SubstancesWater • Most abundant compound in living material • Two-thirds of the weight of an adult human • Major component of all body fluids • Medium for most metabolic reactions • Important role in transporting chemicals in the body • Absorbs and transports heatOxygen (O2) • Used by organelles to release energy from nutrients in order to drive cell’s metabolic activities • Necessary for survival 28
  29. 29. Inorganic SubstancesCarbon dioxide (CO2) • Waste product released during metabolic reactions • Must be removed from the bodyInorganic salts • Abundant in body fluids • Sources of necessary ions (Na+, Cl-, K+, Ca2+, etc.) • Play important roles in metabolism 29
  30. 30. Organic Substances Carbohydrates• Provide energy to cells• Supply materials to build cell structures• Water-soluble• Contain C, H, and O• Ratio of H to O close to 2:1 (C6H12O6)• Monosaccharides – glucose, fructose• Disaccharides – sucrose, lactose• Polysaccharides – glycogen, cellulose 30
  31. 31. Organic Substances Carbohydrates Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. H O C Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. H C O H HH O C H H C O H Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. H C O H C O O H H H C O H H C O H H C O O H H C O H C C H H O H(a) Some glucose molecules (b) More commonly, glucose (c) This shape symbolizes (C6H12O6) have a straight molecules form a ring structure. the ring structure of a chain of carbon atoms. glucose molecule. 31
  32. 32. Organic Substances CarbohydratesCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. O O O O (a) Monosaccharide (b) Disaccharide Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. O O O (c) Polysaccharide 32
  33. 33. Organic Substances Lipids• Soluble in organic solvents; insoluble in water• Fats (triglycerides) • Used primarily for energy; most common lipid in the body • Contain C, H, and O but less O than carbohydrates (C57H110O6) • Building blocks are 1 glycerol and 3 fatty acids per molecule • Saturated and unsaturated Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. H O H H H H H H H H H H H H H H H H C O C C C C C C C C C C C C C C C C H H H H H H H H H H H H H H H H O H H H H H H H H H H H H H H H H H H C O C C C C C C C C C C C C C C C C C C H H H H H H H H H H H H H H H H H H O H H H H H H H C O C C C C C C H H H H H H 33 Glycerol Fatty acid portion portions
  34. 34. Neutral Fats• Triglycerides are formed from a fatty acid and glycerol (a sugar).• They are the most plentiful source of stored energy to our bodies. – Two types: • Saturated- contain only single bonds • Unsaturated- contains one(mono) or more(poly) double bonds• Short, unsaturated fats are liquids (oils) and come from plants.• Long, saturated fats are solid (butter and meat fat) and come from animals.
  35. 35. Organic Substances Lipids • Phospholipids • Building blocks are 1 glycerol, 2 fatty acids, and 1 phosphate per molecule • Hydrophilic and hydrophobic • Major component of cell membranes Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. H Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. H H C O Fatty acid H C O Fatty acid H C O Fatty acid Water-insoluble (hydrophobic) H C O Fatty acid “tail” O H H H H C O Fatty acid Water-soluble H C O P O C C N (hydrophilic) H H “head” H O– H HGlycerol portion Phosphate portion (a) A fat molecule (b) A phospholipid molecule (c) Schematic representation 35 (the unshaded portion may vary) of a phospholipid molecule
  36. 36. Organic Substances Lipids • Steroids • Four connected rings of carbon • Widely distributed in the body, various functions • Component of cell membrane • Used to synthesize hormones • CholesterolCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. CH3 CH3 H2 CH3 H C C CH CH2 CH2 CH2 CH H2 C C CH2 CH3 CH3 H2 C HC CH CH2 H2C C CH HO C C CH2 H C C H2 H 36 (a) General structure of a steroid (b) Cholesterol
  37. 37. Organic Substances Proteins• Structural material • Protein building blocks are• Energy source amino acids• Hormones • Amino acids held• Receptors together with peptide bonds• Enzymes H• Antibodies H C C C H H H C C H S C R H C H H C H H N C C OH H N C C OH H N C C OH H H O H H O H H O 37
  38. 38. Organic Substances Proteins Four Levels of Protein Structure Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Amino acids H HPrimary structure Tertiary structure Three-dimensional C C R H N H H C O H folding C CSecondary structure C O H H H N H H HO N C R H C C R R R C N N H O C N C C R O O C N H C H R R H H O R C C C H N H N H H C O O H C C N R Quaternary structure C O H N O C H H H H H R R C C R N C N C N H O C R C O C H O C N H H HO R R R C H C C N C H H C N H N C O O H Pleated C O H N Coiled O H H structure C C structure 38
  39. 39. Organic Substances Nucleic Acids• Carry genes• Encode amino acid sequences of proteins• Building blocks are nucleotides Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. P B S• DNA (deoxyribonucleic acid) – double polynucleotide• RNA (ribonucleic acid) – single polynucleotide 39
  40. 40. Organic Substances Nucleic Acids Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. S P B P B B P S S S P B P B B P S S S P B P B B P S S S P B P B B P S S S P B P B B P S S S P B P B B P S S 40 (a) (b)
  41. 41. 2.3 From Science to Technology CT Scanning and PET Imaging 41
  42. 42. Important Points in Chapter 2: Outcomes to be Assessed2.1: Introduction Give examples of how the study of living materials requires andunderstanding of chemistry.2.2: Structure of Matter Describe how atomic structure determines how atoms interact. Describe the relationships among matter, atoms, and molecules. Explain how molecular and structural formulas symbolize thecomposition of compounds. Describe three types of chemical reactions. Explain what acids, bases, and buffers are. 42 Define pH.
  43. 43. Important Points in Chapter 2: Outcomes to be Assessed Continued2.3: Chemical Constituents of Cells List the major groups of inorganic chemicals common in cells. Describe the general functions of the main classes of organic moleculesin cells. 43
  44. 44. Quiz 2Complete Quiz 2 now! Read Chapter 3. 44
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