Chemistry 2
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Chemistry 2

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Chemistry 2 Chemistry 2 Presentation Transcript

  • - Carbon and the Molecular Diversity of Life
    Overview: Carbon—The Backbone of Biological Molecules
    All living organisms
    Are made up of chemicals based mostly on the element carbon
  • Organic chemistry is the study of carbon compounds
    Organic compounds
    Range from simple molecules to huge, complex molecules
    Carbon has four valence electrons
    This allows it to form four covalent bonds with a variety of atoms
    Carbon atoms can form diverse molecules by bonding to four other atoms
  • Name and Comments
    Space-Filling Model
    Molecular Formula
    Structural Formula
    Ball-and-Stick Model
    H
    (a) Methane
    CH4
    C
    H
    H
    H
    H
    H
    (b) Ethane
    C2H6
    C
    H
    H
    C
    H
    H
    H
    H
    (c) Ethene (ethylene)
    C
    C
    C2H4
    H
    H
    The bonding versatility of carbon
    Allows it to form many diverse molecules, including carbon skeletons
  • H
    H
    C
    C
    C
    C
    H
    H
    C
    H
    H
    H
    H
    H
    H
    C
    H
    H
    H
    H
    H
    H
    H
    H
    H
    H
    H
    H
    C
    C
    C
    C
    C
    C
    C
    H
    H
    H
    H
    H
    H
    H
    H
    H
    H
    H
    H
    (a) Length
    H
    Ethane
    Propane
    H
    H
    H
    H
    H
    H
    H
    H
    H
    H
    H
    C
    C
    C
    C
    C
    C
    C
    C
    H
    H
    H
    H
    (b) Branching
    2-methylpropane
    (commonly called isobutane)
    Butane
    H
    H
    H
    H
    C
    H
    (c) Double bonds
    H
    H
    C
    C
    C
    H
    H
    C
    C
    H
    H
    C
    C
    1-Butene
    2-Butene
    H
    H
    C
    C
    C
    (d) Rings
    Cyclohexane
    Benzene
    Molecular Diversity Arising from Carbon Skeleton Variation
    Carbon chains
    Form the skeletons of most organic molecules
    Vary in length and shape
  • Fat droplets (stained red)
    100 µm
    (b) Mammalian adipose cells
    (a) A fat molecule
    Hydrocarbons are molecules consisting of only carbon and hydrogen
    Hydrocarbons
    Are found in many of a cell’s organic molecules
    Are these polar or nonpolar?
  • H
    H
    H
    C
    H
    H
    C
    H
    H
    H
    H
    H
    H
    H
    (a) Structural isomers
    H
    C
    C
    C
    C
    C
    H
    H
    H
    C
    C
    C
    H
    H
    H
    H
    H
    H
    H
    H
    H
    X
    X
    X
    (b) Geometric isomers
    C
    C
    C
    C
    X
    H
    H
    H
    CO2H
    CO2H
    (c) Enantiomers
    C
    C
    H
    H
    NH2
    NH2
    CH3
    CH3
    Isomers are molecules with the same molecular formula but different structures and properties
    Three types of isomers are
  • L-Dopa
    (effective against Parkinson’s disease)
    D-Dopa
    (biologically inactive)
    Enantiomers
    Are important in the pharmaceutical industry
  • Carbon
    (valence = 4)
    Nitrogen
    (valence = 3)
    Hydrogen
    (valence = 1)
    Oxygen
    (valence = 2)
    O
    H
    N
    C
    The electron configuration of carbon
    Gives it covalent compatibility with many different elements
  • OH
    CH3
    HO
    Estradiol
    Female lion
    OH
    CH3
    CH3
    O
    Testosterone
    Male lion
    Functional groups are the chemically reactive groups of atoms within an organic molecule
    Give organic molecules distinctive chemical properties
    Carbon hydrogen areas are not chemically active.
    Functional groups attached are chemically active
    Are these functional groups polar?
    What about the rest of the molecule?
  • Six functional groups are important in the chemistry of life
    Hydroxyl
    Carbonyl
    Carboxyl
    Amino
    Sulfhydryl
    Phosphate
  • FUNCTIONAL
    GROUP
    HYDROXYL CARBONYL CARBOXYL
    O
    O
    OH
    C
    C
    OH
    (may be written HO )
    STRUCTURE
    In a hydroxyl group (—OH), a hydrogen atom is bonded to an oxygen atom, which in turn is bonded to the carbon skeleton of the organic molecule. (Do not confuse this functional group with the hydroxide ion, OH–.)
    The carbonyl group( CO) consists of a carbon atom joined to an oxygen atom by a double bond.
    When an oxygen atom is double-bonded to a carbon atom that is also bonded to a hydroxyl group, the entire assembly of atoms is called a carboxyl group (—COOH).

    Some important functional groups of organic compounds
  • Ketones if the carbonyl group is within a carbon skeleton
    Aldehydes if the carbonyl group is at the end of the carbon skeleton
    NAME OF COMPOUNDS
    Alcohols (their specific names usually end in -ol)
    Carboxylic acids, or organic acids
    EXAMPLE
    H
    H
    H
    H
    O
    O
    C
    C
    H
    OH
    C
    C
    H
    C
    H
    C
    H
    OH
    H
    H
    H
    H
    C
    Ethanol, the alcohol present in alcoholic beverages
    H
    H
    Acetic acid, which gives vinegar its sour tatste
    Acetone, the simplest ketone
    H
    H
    O
    C
    C
    C
    H
    H
    H
    H
    Propanal, an aldehyde
    FUNCTIONAL
    GROUP
    HYDROXYL CARBONYL CARBOXYL
  •  A ketone and an aldehyde may be structural isomers with different properties, as is the case for acetone and propanal.
     Is polar as a result of the electronegative oxygen atom drawing electrons toward itself.
     Attracts water molecules, helping dissolve organic compounds such as sugars (see Figure 5.3).
    FUNCTIONALPROPERTIES
     Has acidic properties because it is a source of hydrogen ions.
    The covalent bond between oxygen and hydrogen is so polar that hydrogen ions (H+) tend to dissociate reversibly; for example,
    H
    H
    O
    O
    + H+
    H
    C
    H
    C
    C
    C
    OH
    O
    H
    H
     In cells, found in the ionic form, which is called a carboxylate group.
    HYDROXYL CARBONYL CARBOXYL
  • AMINO SULFHYDRYL PHOSPHATE
    O
    H
    SH
    N
    P
    OH
    O
    (may be written HS )
    H
    OH
    In a phosphate group, a phosphorus atom is bonded to four oxygen atoms; one oxygen is bonded to the carbon skeleton; two oxygens carry negative charges; abbreviated P . The phosphate group (—OPO32–) is an ionized form of a phosphoric acid group (—OPO3H2; note the two hydrogens).
    The amino group (—NH2) consists of a nitrogen atom bonded to two hydrogen atoms and to the carbon skeleton.
    The sulfhydryl group consists of a sulfur atom bonded to an atom of hydrogen; resembles a hydroxyl group in shape.
    Some important functional groups of organic compounds
  • OH
    O
    OH
    H
    H
    H
    H
    H
    O
    H
    C
    C
    C
    O
    P
    O
    N
    C
    C
    SH
    H
    C
    C
    HO
    H
    O
    H
    H
    H
    H
    H
    H
    Ethanethiol
    Glycine
    Glycerol phosphate
    Because it also has a carboxyl group, glycine is both an amine and a carboxylic acid; compounds with both groups are called amino acids.
    Some important functional groups of organic compounds
    AMINO SULFHYDRYL PHOSPHATE
    • Two sulfhydryl groups can interact to help stabilize protein structure (see Figure 5.20).
    • A disulfide bond
    Makes the molecule of which it is a part an anion (negatively charged ion).
    Can transfer energy between organic molecules.
    ATP
     Acts as a base; can pick up a proton from the surrounding solution:
    H
    H
    N
    +N
    H
    H
    H
    (nonionized)
    (ionized)
    Ionized, with a charge of 1+, under cellular conditions.
    Some important functional groups of organic compounds
    AMINO SULFHYDRYL PHOSPHATE
  • Nucleotides can act as short-term carriers of chemical energy
    ATP
    adenosine triphosphate
    Formed by oxidation of food. The phosphates are linked by phosphoanhydride bonds which release large amounts of useful energy when broken. The terminal phosphate is frequently split off by hydrolysis, releasing energy which drives energy-requiring reactions in the cell