BMS100 Outline - Chapter 2: Chemical Basis Of Life
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  1. Elements and Atoms
    1. Naturally occurring matter on earth is composed of 92 elements.
    2. Atoms are the smallest complete units of each element.

  2. Atomic structure
    1. Each atom has a nucleus, which contains protons and neutrons, and one or more electrons orbiting the nucleus in "shells."
    2. Electrons are negatively charged; protons are positively charged.
    3. With most elements, the atoms tend to bond one or more other atoms and form molecules.
    4. Atoms of different elements may bond to form a "compound."

  3. Bonding of atoms: ionic bonding, covalent bonding, hydrogen bonding
    • Atoms with completely filled outer shells are inert (stable).
    • Atoms with incompletely filled outer shells tend to gain, lose, or share electrons to achieve stability.
    1. Ionic Bonding
      1. Atoms that lose electrons become positively charged ions (cations).
        • examples - sodium, potassium, calcium, hydrogen
      2. Atoms that gain electrons become negatively charged ions (anions).
        • examples - chloride, phosphate, bicarbonate
      3. Ions with opposite charges attract each other and form ionic bonds.
        • examples: sodium chloride, calcium phosphate
        • What happens when sodium chloride is mixed with water?
      4. Compounds that release ions when they dissolve are electrolytes. Why are electrolytes so important in human physiology?
    2. Covalent Bonding - atoms share electrons
    3. Hydrogen Bonding - weak bond between H and O or N

  4. Molecules / compounds / formulas
    1. A molecular formula represents the types and numbers of atoms in a molecule. Know the formulas for water, oxygen gas, carbon dioxide, glucose, and ammonia.
    2. Body Composition of a Lean Male: water - 61%; protein* - 17%; fat* - 14%; minerals - 6%; carbohydrates* - 1-2%; nucleic acids* - <1%
    3. Molecules that contain carbon and hydrogen atoms are "organic" and are usually nonelectrolytes. Other molecules are "inorganic."

  5. Acids and bases
    1. Electrolytes that release hydrogen ions (H+) are acids.
    2. Bases release hydroxyl ions or other ions that react with hydrogen ions.
    3. What happens when an acid and a base are mixed together?
    4. The pH value represents the concentration of H+.
    5. A neutral solution has equal numbers of H+ and OH- and a pH of 7.0.
    6. A solution with more H+ than OH- is acidic and has a pH less than 7.0.
    7. A solution with fewer H+ than OH- is basic (alkaline) and has a pH greater than 7.0.

  6. Carbohydrates
    1. provide much of the energy that cells require
    2. monosaccharides = “one sugar”
      1. includes “simple sugars” such as glucose (blood sugar)
      2. As long as enough glucose enters cells, they utilize it (rather than other substances) for fuel.
      3. What organ normally uses only glucose as an energy source?
    3. disaccharides = “two sugars”
    4. polysaccharides = “many sugars" (complex carbohydrates)
      1. Know the general structure of a starch or glycogen molecule.
      2. Under what conditions is glycogen synthesized (formed)? Under what conditions is it decomposed (broken down)?

  7. Proteins
    1. functions (partial list): structural proteins, enzymes, hemoglobin, ion channels, hormones, antibodies, cell surface markers and receptors, energy source
    2. The “building blocks” of proteins are amino acids - twenty (20) different types
    3. Each amino acid has an amino group, a carboxylic acid group, and an R group
    4. Proteins vary in the numbers and sequences of their amino acids ("primary structure").
    5. Each protein molecule folds into a complex conformation (3D shape) which is based on its primary structure. The 3D conformation of a protein determines its function.
    6. Altered pH, various chemicals, etc. can change protein conformations.

  8. Lipids - are insoluble in water
    1. Triglycerides
      • “building blocks” = glycerol + three fatty acids
      • "fats" are triglycerides that are solid at room temp.
      • "oils" (edible oils) are triglycerides that are liquid at room temp.
      • high energy content (9 cal./g., more than 2X carb. or protein)
    2. Fatty acids
      • saturated fatty acids - are saturated with hydrogen; are generally more solid at room temp.
      • unsaturated fatty acids - are not saturated with hydrogen; are generally more liquid at room temp.
    3. Phospholipids - similar to triglycerides; abundant in cell membranes (Ch. 3)
    4. Steroids
      • all include four carbon rings
      • cholesterol is produced in the liver then converted to other steroids
      • in the body, most steroids function as hormones
      • names often include "stero," for example, cholesterol, progesterone, testosterone

  9. Nucleic acids
    1. DNA molecules (genes) store information; messenger RNA molecules are transcripts of genes
    2. the information in nucleic acids allows a cell to correctly synthesize _?_ molecules.

Chapter 2 Questions at Online Learning Center – 2, 3, 5, 6, 7, 8, 10, 11, 12, 13, 14, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 31, 37, 38, 39, 40, 42, 43, 44, 45
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January 2011