BIO 3 Introduction to Biology Instructor:  Francisca Herrera
What is a living thing? Living organisms are a carbon- and water-based cellular form with complex organization and heritab...
Living organisms are: water- and carbon- based
<ul><li>Matter </li></ul><ul><li>Atoms </li></ul>
Atoms <ul><li>Organisms are chemical machines </li></ul><ul><ul><li>one must know chemistry in order to understand biology...
 
Atoms <ul><li>All atoms have the same structure </li></ul><ul><ul><li>at the core is a dense nucleus comprised of two suba...
 
Atoms <ul><li>An atom can be characterized by the number of protons it has or by its overall mass </li></ul><ul><ul><li>at...
 
Atoms <ul><li>Electrons determine the chemical behavior of atoms </li></ul><ul><ul><li>these subatomic components are the ...
Atoms <ul><li>Electrons are associated with energy </li></ul><ul><ul><li>electrons have energy of position, called  potent...
Atoms <ul><li>Electron shells have specific numbers of orbitals that may be filled with electrons </li></ul><ul><ul><li>at...
Atoms <ul><li>Ions  – atoms that have gained or lost one or more electrons </li></ul><ul><li>Isotopes  – atoms that have t...
Atoms <ul><li>Some isotopes are unstable and break up into particles with lower atomic numbers </li></ul><ul><ul><li>this ...
Figure 3.5 Isotopes of the element carbon
<ul><li>Simple Molecules </li></ul><ul><li>Water </li></ul>
Molecules <ul><li>Molecule  forms when atoms are held together with energy </li></ul><ul><ul><li>the energy (force) holdin...
Molecules <ul><li>Ionic bonds   </li></ul><ul><ul><li>involve the attraction of opposite electrical charges </li></ul></ul...
Fig. 3.8
Molecules <ul><li>Covalent bonds   </li></ul><ul><ul><li>form between two atoms when they share electrons </li></ul></ul><...
Figure 3.9  Water molecules contain two covalent bonds
Molecules <ul><li>Hydrogen bonds  are weak bonds that form due to covalent bonds where one nucleus attracts the shared ele...
Fig. 3.9
Molecules <ul><li>Hydrogen bonds form in association with  polar molecules </li></ul><ul><ul><li>each atom with a partial ...
Figure 3.10 Hydrogen bonding water molecules
Water <ul><li>Water is essential for life </li></ul><ul><ul><li>the chemistry of life is water chemistry </li></ul></ul><u...
<ul><li>Heat Storage </li></ul><ul><ul><li>water temperature changes slowly and holds temperature well </li></ul></ul><ul>...
Fig. 3.11
Water <ul><li>Water molecules are sticky </li></ul><ul><ul><li>cohesion  – when one water molecule is attracted to another...
Fig. 3.12
 
Water <ul><li>Water is highly polar </li></ul><ul><ul><li>in solution, water molecules tend to form the maximum number of ...
Fig. 3.13
Water <ul><li>The covalent bond within a water molecule breaks spontaneously </li></ul><ul><li>This produces two ions in a...
Water <ul><li>The amount of ionized hydrogen from water in a solution can be measured as pH </li></ul><ul><li>The pH scale...
Figure 3.14: The pH scale ACIDIC: more free H + BASIC:  more free OH -
Water <ul><li>Pure water has a pH of 7 </li></ul><ul><ul><li>there are equal amounts of [H+] relative to [OH-] </li></ul><...
Water <ul><li>Acids and bases are routinely encountered by living organisms </li></ul><ul><ul><li>from metabolic activitie...
Water <ul><li>Buffer  – a chemical substance that takes up or releases hydrogen ions </li></ul><ul><ul><li>buffers don’t r...
Today’s Journal Entry <ul><li>Under the activities menu of the virtual classroom, click on the  Journals  link </li></ul><...
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Unit2 Lecture2

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  • Welcome to the Introduction to Biology course (BIO 003) at Los Angeles Trade Technical College. This is an introductory course dealing with the fundamental properties of living things. You are viewing the first lecture of unit 2.
  • Unit2 Lecture2

    1. 1. BIO 3 Introduction to Biology Instructor: Francisca Herrera
    2. 2. What is a living thing? Living organisms are a carbon- and water-based cellular form with complex organization and heritable genetic information. They undergo metabolism, possess a capacity to grow, respond to stimuli, reproduce, and, through natural selection, adapt to their environment in successive generations.
    3. 3. Living organisms are: water- and carbon- based
    4. 4. <ul><li>Matter </li></ul><ul><li>Atoms </li></ul>
    5. 5. Atoms <ul><li>Organisms are chemical machines </li></ul><ul><ul><li>one must know chemistry in order to understand biology </li></ul></ul><ul><li>Any substance in the universe that has mass and occupies space is comprised of matter </li></ul><ul><ul><li>all matter is made up of atoms </li></ul></ul>
    6. 7. Atoms <ul><li>All atoms have the same structure </li></ul><ul><ul><li>at the core is a dense nucleus comprised of two subatomic particles </li></ul></ul><ul><ul><ul><li>protons (positively charged) </li></ul></ul></ul><ul><ul><ul><li>neutrons (no associated charge) </li></ul></ul></ul><ul><ul><li>orbiting the nucleus is a cloud of another type of subatomic particle </li></ul></ul><ul><ul><ul><li>electrons (negatively charged) </li></ul></ul></ul>
    7. 9. Atoms <ul><li>An atom can be characterized by the number of protons it has or by its overall mass </li></ul><ul><ul><li>atomic number </li></ul></ul><ul><ul><ul><li>the number of protons in the nucleus </li></ul></ul></ul><ul><ul><li>mass number </li></ul></ul><ul><ul><ul><li>the number of protons plus neutrons in the nucleus </li></ul></ul></ul><ul><ul><ul><li>electrons have negligible mass </li></ul></ul></ul>
    8. 11. Atoms <ul><li>Electrons determine the chemical behavior of atoms </li></ul><ul><ul><li>these subatomic components are the parts of the atom that come close enough to each other in nature to interact </li></ul></ul>
    9. 12. Atoms <ul><li>Electrons are associated with energy </li></ul><ul><ul><li>electrons have energy of position, called potential energy </li></ul></ul><ul><ul><li>the field of energy around an atom is arranged as levels called electron shells </li></ul></ul><ul><ul><ul><li>within this volume of space, orbitals are where electrons are most likely to be found </li></ul></ul></ul>
    10. 13. Atoms <ul><li>Electron shells have specific numbers of orbitals that may be filled with electrons </li></ul><ul><ul><li>atoms that have incomplete electron orbitals tend to be more reactive </li></ul></ul><ul><ul><li>atoms will lose, gain, or share electrons in order to fill completely their outermost electron shell </li></ul></ul><ul><ul><li>these actions are the basis of chemical bonding </li></ul></ul>
    11. 14. Atoms <ul><li>Ions – atoms that have gained or lost one or more electrons </li></ul><ul><li>Isotopes – atoms that have the same number of protons but different numbers of neutrons </li></ul><ul><ul><li>most elements in nature exist as mixtures of different isotopes </li></ul></ul>
    12. 15. Atoms <ul><li>Some isotopes are unstable and break up into particles with lower atomic numbers </li></ul><ul><ul><li>this process is known as radioactive decay </li></ul></ul><ul><li>Radioactive isotopes have multiple uses </li></ul><ul><ul><li>nuclear medicine </li></ul></ul><ul><ul><li>dating fossils </li></ul></ul>
    13. 16. Figure 3.5 Isotopes of the element carbon
    14. 17. <ul><li>Simple Molecules </li></ul><ul><li>Water </li></ul>
    15. 18. Molecules <ul><li>Molecule forms when atoms are held together with energy </li></ul><ul><ul><li>the energy (force) holding two atoms together is called a chemical bond </li></ul></ul><ul><ul><li>there are 3 principal types of chemical bonds </li></ul></ul><ul><ul><ul><ul><li>ionic </li></ul></ul></ul></ul><ul><ul><ul><ul><li>covalent </li></ul></ul></ul></ul><ul><ul><ul><ul><li>hydrogen </li></ul></ul></ul></ul>
    16. 19. Molecules <ul><li>Ionic bonds </li></ul><ul><ul><li>involve the attraction of opposite electrical charges </li></ul></ul><ul><ul><li>Molecules comprised of these bonds are often most stable as crystals </li></ul></ul>
    17. 20. Fig. 3.8
    18. 21. Molecules <ul><li>Covalent bonds </li></ul><ul><ul><li>form between two atoms when they share electrons </li></ul></ul><ul><ul><li>the number of electrons shared varies depending on how many the atom needs to fill its outermost electron shell </li></ul></ul><ul><ul><li>covalent bonds are stronger than ionic bonds </li></ul></ul>
    19. 22. Figure 3.9 Water molecules contain two covalent bonds
    20. 23. Molecules <ul><li>Hydrogen bonds are weak bonds that form due to covalent bonds where one nucleus attracts the shared electrons more than another nucleus </li></ul><ul><ul><li>this attraction for electrons by a nucleus is called the atom’s electronegativity </li></ul></ul><ul><ul><li>this results in partial charges in the atoms that are unequally sharing electrons </li></ul></ul>
    21. 24. Fig. 3.9
    22. 25. Molecules <ul><li>Hydrogen bonds form in association with polar molecules </li></ul><ul><ul><li>each atom with a partial charge acts like a magnet to bond weakly to another polar atom with an opposite charge </li></ul></ul><ul><ul><li>the additive effects of many hydrogen bonding interactions can add collective strength to the bonds </li></ul></ul>
    23. 26. Figure 3.10 Hydrogen bonding water molecules
    24. 27. Water <ul><li>Water is essential for life </li></ul><ul><ul><li>the chemistry of life is water chemistry </li></ul></ul><ul><li>Water is a polar molecule </li></ul><ul><ul><li>water can form hydrogen bonds </li></ul></ul><ul><ul><li>hydrogen bonding confers on water many different special properties </li></ul></ul>
    25. 28. <ul><li>Heat Storage </li></ul><ul><ul><li>water temperature changes slowly and holds temperature well </li></ul></ul><ul><li>Ice Formation </li></ul><ul><ul><li>few hydrogen bonds break at low temperatures </li></ul></ul><ul><ul><ul><li>water becomes less dense as it freezes because hydrogen bonds stabilize and hold water molecules farther apart </li></ul></ul></ul><ul><li>High Heat of Vaporization </li></ul><ul><ul><li>at high temperatures, hydrogen bonds can be broken (requires tremendous energy) </li></ul></ul>Water
    26. 29. Fig. 3.11
    27. 30. Water <ul><li>Water molecules are sticky </li></ul><ul><ul><li>cohesion – when one water molecule is attracted to another water molecule </li></ul></ul><ul><ul><li>adhesion – when polar molecules other than water stick to a water molecule </li></ul></ul>
    28. 31. Fig. 3.12
    29. 33. Water <ul><li>Water is highly polar </li></ul><ul><ul><li>in solution, water molecules tend to form the maximum number of hydrogen bonds </li></ul></ul><ul><ul><ul><li>hydrophilic molecules are attracted to water and dissolve easily in it </li></ul></ul></ul><ul><ul><ul><ul><li>these molecules are also polar and can form hydrogen bonds </li></ul></ul></ul></ul><ul><ul><ul><li>hydrophobic molecules are repelled by water and do not dissolve </li></ul></ul></ul><ul><ul><ul><ul><li>these molecules are non-polar and do not form hydrogen bonds </li></ul></ul></ul></ul>
    30. 34. Fig. 3.13
    31. 35. Water <ul><li>The covalent bond within a water molecule breaks spontaneously </li></ul><ul><li>This produces two ions in a process called ionization </li></ul><ul><ul><li>because of the great strength of covalent bonds, this does not occur too often </li></ul></ul>H 2 O  OH - + H + Water Hydroxide Hydrogen
    32. 36. Water <ul><li>The amount of ionized hydrogen from water in a solution can be measured as pH </li></ul><ul><li>The pH scale is logarithmic , which means that a pH scale difference of 1 unit actually represents a 10-fold change in hydrogen ion concentration </li></ul>pH = -log[H + ]
    33. 37. Figure 3.14: The pH scale ACIDIC: more free H + BASIC: more free OH -
    34. 38. Water <ul><li>Pure water has a pH of 7 </li></ul><ul><ul><li>there are equal amounts of [H+] relative to [OH-] </li></ul></ul><ul><li>The pH in most living cells and their environments is fairly close to 7 </li></ul><ul><ul><li>proteins involved in metabolism are sensitive to any pH changes </li></ul></ul>
    35. 39. Water <ul><li>Acids and bases are routinely encountered by living organisms </li></ul><ul><ul><li>from metabolic activities (i.e., chemical reactions) </li></ul></ul><ul><ul><li>from dietary intake and processing </li></ul></ul><ul><li>Organisms use buffers to minimize pH disturbances </li></ul>
    36. 40. Water <ul><li>Buffer – a chemical substance that takes up or releases hydrogen ions </li></ul><ul><ul><li>buffers don’t remove the acid or the base affecting pH but minimize their effect on it </li></ul></ul><ul><ul><li>most buffers are pairs of substances, one an acid and one a base </li></ul></ul>
    37. 41. Today’s Journal Entry <ul><li>Under the activities menu of the virtual classroom, click on the Journals link </li></ul><ul><li>Topic 2 – Atoms and Simple Molecules </li></ul><ul><ul><li>There are no wrong answers in the journal entries. </li></ul></ul><ul><ul><li>Answer in complete sentences, in a clear and concise manner. </li></ul></ul>

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