The Molecules of Cells

							                     The Molecules of Cells
I.     Life’s molecular diversity is based on the properties of carbon
       a. Next to water, carbon compounds are the most abundant in
          living organisms
       b. ORGANIC COMPOUNDS – compounds synthesized by cells
          and containing carbon
       c. Carbon outer shell has 4 electrons and needs 8 total
       d. HYDROCARBONS  compounds composed of only C and H
       e. ISOMERS  same molecular formula but different structures

II.    Functional Groups help determine the properties of organic
       compounds
       a. FUNCTIONAL GROUPS  groups of atoms, in an organic
          molecule, that usually participate in a chemical reaction




       b. HYDROPHILIC  water soluble
              i. As a result of polar covalent bonds
       c. Compounds may have more than one functional group,
          therefore have properties of both

III.   Cells make a huge number of large molecules from a small set of
       molecules
       a. MACROMOLECULES  gigantic molecules (ex. Carbs,
          lipids, proteins, nucleic acids)
      b. POLYMERS  “many parts”, a large molecule consisting of
         many similar units strung together




      c. MONOMERS  the units of polymers, the building blocks
      d. DEHYDRATION SYNTHESIS  the removal of a water
         molecule to link monomers
      e. HYDROLYSIS  breaking apart a polymer by adding a water
         molecule

IV.   Monosaccharides are the simplest carbohydrates
      a. CARBOHYDRATE  refers to a class of molecules ranging
         from small sugar to large polysaccharides (polymers of sugar
         monomers)
     b. MONOSACCHARIDES  sugar monomers (“single sugar”)
          i. Examples  glucose, fructose




     c. Generally have the formula C6H12O6
           i. Isomers  different properties
     d. Not usually shown in linear formation; form rings in solution
     e. Monosaccharides are the main fuel for cells (especially glucose)
     f. Carbon skeletons are used to form other compounds, like amino
        acids

V.   Cells link single sugars to form disaccharides
     a. Disaccharide  “double sugar”; joined monosaccharides




     b. Accomplished by DEHYDRATION SYNTHESIS
      c.
           Disaccharide                     Monosaccharide
             Maltose                       Glucose + Glucose
              Sucrose                      Glucose + Fructose
              Lactose                      Glucose + Galactose

VI.   How sweet is sweet?
      a. Sweet receptors on our tongue
      b. Sugar binds to these receptors, but not the only compound that
         can do this
            i. Aspartame (Equal or Nutrasweet) made of amino acids
      c. All sweetness is relative to sucrose (table sugar)
            i. Bitter aftertaste; compounds are also binding to bitter
               receptors on tongue

VII. Polysaccharides are long chains of sugar units
     a. POLYSACCHARIDES  polymers of a few hundred to a few
        thousand monosaccharides linked by dehydration synthesis
b. STARCH  a storage polysaccharide found in plants
      i. Composed of glucose (monomer)
     ii. Broken down (hydrolyzed) when plant needs energy
    iii. Humans and animals can also break it down when they
         eat it (potatoes and grains)




c. GLYCOGEN  a storage polysaccharide in animals
      i. Nearly identical to start except shape is slightly different
d. CELLULOSE  a building polysaccharide
      i. Form tough walls that enclose plant cells and WOOD
     ii. NOT able to be broken down by animals
    iii. Need special micro-organisms in digestive tract to break
         cellulose down
VIII. Lipids include fat, which are mostly energy storage molecules
      a. LIPIDS  Diverse compounds of C and H linked by
         NONPOLAR covalent bonds
      b. HYDROPHOBIC  NOT water soluble
      c. FAT  a large lipid made from two kinds of smaller
         molecules; glycerol and fatty acids




      d. TRIGLYCERIDE  a synonym for fat; glycerol + 3 (tri) fatty
         acids
      e. SATURATED vs UNSATURATED  maximum number of
         H’s, versus having double bonds
IX.   Phospholipids, waxes, and steroids are lipids with a variety of
      functions
      a. Some lipids help build cell membranes, protect body surfaces
         and regulate cellular and body function




      b. PHOSPHOLIPIDS  a major component in cell membranes
           i. Similar structure to fat but contains PHOSPHOROUS
              and have only two fatty acids




      c. WAXES  one fatty acid linked to an alcohol
           i. More hydrophobic then fats, making them effective
              coating on fruits, insects, etc…
     d. STEROIDS  lipids whose carbon skeleton is bent to form
        four fused rings
           i. Cholesterol is a type of steroid




          ii. ALL steroids have some structure of rings
         iii. Used in cell membranes and hormone production

X.   Anabolic steroids and related substances pose health risks
     a. ANABOLIC STEROIDS  synthetic variants of the male
        hormone testosterone
           i. Will help build up muscle mass
          ii. Downside  liver damage, cholesterol problems, high
              blood pressure, decreased output of sex hormones
XI.   Proteins are essential to the structures and activities of life
      a. PROTEIN  “first place”; a polymer constructed from amino
         acid monomers
             i. Many types of proteins
                   1. Structural proteins
                   2. Contractile proteins
                   3. Storage proteins
                   4. Defensive proteins
                   5. Transport proteins
                   6. Signal proteins




      b. ENZYMES  a protein that serves as a chemical catalyst
XII. Proteins are made from just 20 kinds of amino acids
     a. AMINO ACIDS  have an amino group and a carboxyl group




     b. The “R” is the variable group; what goes in that spot will
        determine which of the 20 amino acids you have and the
        resulting properties

XIII. Amino acids can be linked by peptide bonds
      a. PEPTIDE BONDS  the resulting covalent linkage between
         two amino acids
      b. DIPEPTIDE  two attached amino acids
      c. POLYPEPTIDE  a chain of amino acids
XIV. Overview: A protein’s specific shape determines its function
     a. A protein consists of one or more polypeptide chains folded
        into a unique shape
     b. The SPECIFIC 3-D shape determines the specific function
     c. DENATURATION  polypeptides unravel and lose their
        specific shape and function




            i. Temperature, pH, salt concentration ALL can denature
               proteins

XV. Four MAJOR points about proteins
    a. A protein’s primary structure is its amino acid sequence
b. Secondary structure is polypeptide coiling or folding produced
   by hydrogen bonding




c. Tertiary structure is the overall shape of a polypeptide




d. Quaternary structure is the relationship among multiple
   polypeptides of a protein
XVI. Nucleic acids are information-rich polymers of nucleotides




      a. NUCLEIC ACIDS  polymers that serve as blueprints for
         proteins
b. 2 types
       i. DNA  Deoxyribonucleic Acid
      ii. RNA  Ribonucleic Acid
c. DNA contain genes which control the amino acid sequence of
   the proteins being produced
d. DNA doesn’t work directly, uses RNA as an intermediate
e. NUCLEOTIDES  monomers that make up nucleic acids
       i. 5 carbon sugar (pentose)
      ii. Phosphate group
     iii. Nitrogenous base
f. RNA is a single strand of nucleotide units
g. DNA is a double strand (double helix) with the nitrogenous
   bases fusing together to connect the two strands