Carbohydrates_ Lipids_ and proteins

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Carbohydrates_ Lipids_ and proteins Powered By Docstoc
					Topic 3.2
   Do you think we are what we eat?
   How does what we eat determine who we are?
•   Organic compounds
    –   Almost all the molecules a cell makes are
        compounds of carbon atoms bonded to one another
        and to atoms of other elements.
    –   Carbon has 4 outer electrons and completes its outer
        shell by sharing electrons with other atoms in four
        covalent bonds.
    –   Hydrocarbons
        • Compounds only composed of carbon and hydrogen
        • They are all nonpolar molecules
        • Example:methane
   More organic…
       Carbon skeleton
         Carbon atoms can bond together in chains or various
          lengths. Ex. Ethane and propane
         Can be unbranched (butane) or branched (isobutane)
       Isomers
         Some compounds have the same molecular formula
          but different structures (1-Butene and 2-Butene)
         This will result in unique properties.
   Organic compound properties are influenced
    by:
       Size and shape of its carbon skeleton
       Atoms attached to skeleton (Functional Group)
   Functional group
       Groups of atoms that usually participate in chemical
        reactions
       Functional groups of organic compounds are polar
         Oxygen or nitrogen atoms exert a strong pull on shared
          electrons.
         Makes the compounds hydrophilic (water-loving) and
          therefore soluble in water
         Sets for necessary conditions for their roles in water-
          based life. Female and male sex hormones differ mainly
          in functional groups help produce contrasting male
          and female features
•   Hydroxyl group
    – Hydrogen atom bonded to an oxygen atom, bonded to the carbon
      skeleton of a molecule
    – Ex. ethanol
•   Carbonyl group
    – Carbon atom linked by a double bond to an oxygen atom.
    – If carbon atom of carbonyl group is at the end of a carbon skeleton,
      the compound is an aldehyde.
    – If carbonyl group is within a carbon chain, the compound is a
      ketone.
•   Carboxyl group
    • Carbon double bonded to an oxygen and also bonded to a
      hydroxyl group.
    • Acts as an acid by contributing an H+ to a solution and becoming
      ionized.
    • Carboxylic acid
•   Amino group
    •   Composed of nitrogen atom bonded to two
        hydrogen atoms.
    •   Amine
    •   Amino acids contain both a carboxyl group and
        amino group
•   Phosphate group
    •   Phosphorous atom bonded to four oxygen atoms
    •   Usually ionized and attached to the carbon skeleton
        by one of its oxygen atoms.
    •   ATP
   On a molecular scale, these molecules are
    gigantic
   Four main classes:
       Carbohydrates
       Lipids
       Proteins
       Nucleic acids
   Polymers
     Large molecules consisting of many identical or similar
      molecular units strung together.
     For proteins, there are bout a trillion different kinds in
      nature
   Monomers
     Units that serve as building blocks of polymers
     A cell makes all of its diverse macromolecules with
      about 40 to 50 common monomers.
     DNA is made from 4 monomers (nucleotides)
     Only 20 amino acids, in different sequences, that make
      up all of your proteins
   Dehydration Reaction
       A reaction that removes a molecule of water.
       Cells link monomers together to form polymers
       One monomer loses a hydroxyl group and the other
        loses a hydrogen atom and forms a new covalent
        bond.
       Require the help of enzymes
   Hydrolysis
       Breaks down polymers into monomers with water.
       Hydrogen joins to one monomer, and a hydroxyl
        group joins to the adjacent monomer.
       Require the help of enzymes
   Ranges from small sugar molecules to large
    polysaccharides
   Three types:
       Monosaccharides
       Disaccharides
       Polysaccharides
   Carbohydrate monomers (single-unit sugars)
   Examples: Glucose and fructose
   Molecular formula is usually a multiple of
    CH20; formula for glucose is C6H12O6.
   Two trademarks of a sugar:
       A number Hydroxyl groups (make it an alcohol)
       A carbonyl group (depending on location, make it an
        aldehyde or ketone
       Glucose and fructose are isomers
        Same chemical formula, different placement of
        
        carbonyl groups
       Different properties: fructose is sweeter than glucose
•   In aqueous solutions, usually form rings
       Other types of sugars: pentose, hexose
       Main fuel molecules for cellular work, and raw
        materials for making amino acids
       Mono’s not used immediately are usually
        incorporated into di’s and poly’s
   Form via a dehydration reaction between two
    monosaccharides.
   Most common example: sucrose
       Made from glucose and fructose
       Found in plant sap, stems of sugar cane (table sugar)
   Example: maltose
       Made from two glucose molecules
       Used in germinating seeds, beer, malted milk shakes,
        and malted milk ball candy
   Polymers of monosaccharides linked together by
    dehydration reactions
   Some are storage molecules, which cells break
    down as needed to obtain sugar
   Example: starch
       Found in roots and other tissues of plants, consists
        entirely of glucose monomers.
       Potatoes and grains are made of starch
         Hydrolyze it within digestive system and break down to
          glucose monomers.
   Example: glycogen
       Form animals store excess sugar
       More highly branched than starch
       Stored as granules in our liver and muscle cells,
        which hydrolyze the glycogen to release glucose
        when it is needed.
   Example: Cellulose
       Most abundant organic compound on Earth, forms
        cable-like fibrils in the tough walls that enclose plant
        cells.
       Resembles starch and glycogen in being a polymer of
        glucose, but form unbranched rod:
         Joined by hydrogen bonds arranged parallel to each
          other makes strong fibrils in trees
       Can’t be hydrolyzed by most animals
         Not a nutrient for humans, but helps keep out digestive
          system healthy: Most fresh fruits, vegetables, and grains
          are rich in fiber
         Cows and termites can digest celluse via microorganism
          in their Digestive Tract
   Types: Fats, Phospholipids, waves, and
    steroids
   Consist mainly of carbon and hydrogen atoms
    linked by nonpolar covalent bonds.
   Not attracted to water molecules: hydrophobic
    (water-fearing)
       Salad dressing: oil (lipid) separates from vinegar
        (mostly water)
   Fat- a large lipid made from two kids of
    smaller molecules
       Gyclerol- 1
         Alcohol with 3 carbons, each bearing a hydroxyl group
       Fatty acids- 3
         Consists of a carboxyl group and a hydrocarbon chain
          with about 15 carbon atoms
           Carbon in the chains are linked to each other and hydrogen
            atoms by nonpolar covalent bonds make hydrocarbon
            chain hydrophobic
   Main function is energy storage
   A gram of fat stores more than twice as much
    energy as a gram of polysaccharide such as
    starch.
   Triglyceride
       1 glycerol and 3 fatty acids link together via
        dehydration synthesis.
   Unsaturated
       Fatty acids and fats with double bonds
       Kinks prevent the molecule from packing tightly
        together and solidifying at room temperature
       Mostly plant fats: Corn oil, olive oil, and other
        vegetable oils.
   Saturated
       Fats with the maximum number of hydrogens.
       Mostly animal fats: butter and lard are solid at room
        temp.
       May cause atherosclerosis
   Major component of cell membranes
   Structurally similar to fats, but contain
    phosphorous and have only two fatty acids
   Consist of one fatty acid linked to an alcohol.
   More hydrophobic than fats
   Effective natural coatings for fruits such as
    apples and pears.
   Lipids whose carbon skeleton is bent to form
    fused rings
       Three six-sided rings and one five-sided ring.
   Example cholesterol
       Common in animal cell membranes
       Used as a starting material for making other steroids,
        including male and female hormones
       Too much may atherosclerosis
   Polymer constructed from amino acid
    monomers.
   Each of the thousands of different proteins has
    a unique three-dimensional shape that
    corresponds to a specific function.
   Important to cell structure and the function of
    organisms.
   .
   Defensive proteins
     Antibodies in your immune system
   Signal proteins
     Hormones and other messengers
   Hemoglobin
     Delivers 02 to working muscles
   Transport proteins
     Move sugar molecules into cells for energy (insulin)
   Storage proteins
     Ovalbumin (found in egg white) used as a source of amino acid
       for developing embryos
   Most important roles is as enzymes
     Chemical catalysts that speed and regulate virtually all
       chemical reactions in cells
     Example, lactase
   Based on the differing arrangements of a
    common set of just 20 amino acids.
   Amino acids: have an amino group and a
    carboxyl group
       Both of the functional groups are covalently bonded
        to a central atom, called the alpha carbon
       Also bonded to the alpha carbon is a hydrogen atom
        and a chemical group symbolized by the letter R.
         R group is the variable part of an amino acid.
         R group structure determines the specific properties of
         each of the 20 amino acids in proteins.
   Two main types
       Hydrophobic
         Example: Leucine
           R group is nonpolar and hydrophobic
       Hydrophilic
         Polar and charged a.a.’s help proteins dissolve in
          aqueous solutions inside cells.
         Example: Serine
           R group is a hydroxl group
   Cells join amino acids together in a
    dehydration reaction:
     Links the carboxyl group of one amino acid to the
      amino group of the next amino acid as a water
      molecule is removed.
     Form a covalent linkage called a peptide bond
      making a polypeptide
     only 20 amino acids, but make 1,000s of proteins
         Most polypeptides are at least 100 a.a. in length; some
          are thousands
         A functioning protein is one or more polypeptide
          chains twisted, folded, and coiled into a 3-d shape
   Most enzymes are globular in shape
   Structural proteins are typically long and thin.
   Shape is what determines function
   All proteins must recognize and bind to some
    other molecule in order to function.
   Denaturation
     Polypeptide chains unravel, losing their specific
      shape, and function.
     Examples: changes in salt concentration, pH, or
      temperature
   Primary structure
   Secondary structure
   Tertiary structure
   Quaternary structure
   Unique sequence of amino acids
   For any protein to perform its specific function,
    it must have the correct collection of amino
    acids arranged in a precise order.
       Example: a single amino acid change in hemoglobin
        causes sickle-cell disease
   Determined by inherited genetic information.
   Parts of the polypeptide coil or fold into local
    patterns.
       Patterns are maintained by regularly spaced
        hydrogen bonds between the hydrogens of the
        amino group and the oxygen of the carboxyl groups.
   Coiling results in an alpha helix.
   Folding leads to a pleated sheet.
   Many fibrous proteins have the alpha structure
    over most of their length
       Example: structural protein of hair
   Make up the core of many globular proteins
   Dominate some fibrous proteins, including the
    silk proteins of a spider’s web
   Overall, three-dimensional shape of a
    polypeptide.
   Roughly describe as either globular or fibrous
   Generally results from interactions among the
    R groups of amino acids making up the
    polypeptide.
   Results from association of subunits between
    two or more polypeptide chains.
   DNA and RNA
   Deoxyribonucleic Acid (DNA)
       Monomers made up of nucleotides:
         Nucleotides consist of:
            A five carbon sugar, deoxyribose
            Phosphate group
            Nitrogenous base (Adenine, Guanine, Cytosine, Thymine)
       Double helix consists of:
         Sugar-phosphate backbone held by covalent bonds
         Nitrogen bases are hydrogen bonded together; A pairs
          with T and C pairs with G
   Genetic material that organisms inherit from their
    parents.
   Genes
     Specific stretches of DNA that program amino acid
     sequences of proteins.
   Ribonucleic Acid (RNA)
       Intermediary for making proteins
       Also made up of monomers of nucleotides
         Nucleotide of RNA:
           Sugar is ribose (not deoxyribose)
           Phosphate group
           Nitrogen bases (Adenine, Uracil (instead of Thymine,
            Guanine, and Cytosine)
   RNA consists of a single polynucleotide strand
       FYI…The structural significance will make sense we
        talk about protein synthesis later on this year…

				
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posted:7/27/2012
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