Proteins, Carbohydrates, and Lipids - PowerPoint by 3f89OxB3

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									Ch. 3
 Proteins, Carbohydrates, and
             Lipids
                  Objectives

• Know the four macromolecules and give examples of
  each

• Understand how macromolecules are synthesized
  and broken down

• Know the monomer subunits of each macromolecule
                  Molecules
• What is a molecule?

• Living organisms form organic molecules
  – Based on carbon core with various functional
    groups attached
     • -OH, C=O, COOH, NH2, PO4

• Macromolecules – main components of cells
               Macromolecules
• Four types
  – Proteins
  – Carbohydrates
  – Lipids
  – Nucleic acids

• Monomers and polymers
  – Dehydration synthesis
  – Hydrolysis
                          Proteins
• Macromolecule made from amino acid monomers

• Have many functions
  – Enzymes, support, defense, regulation

• Amino Acid structure
  – Central C bond to amino group, carboxyl group, H and
    functional group
     • 20 amino acids exist, differ in their functional groups
20 Amino Acids
• Special cases
  – Glycine

  – Cysteine

  – Proline




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Peptide Linkage
                      Proteins
• Primary structure
  – Sequence of amino acids in a polypeptide chain


• Secondary structure
  – Initial folding of polypeptide chain
     • Alpha helices, beta sheets
                          Proteins
• Tertiary structure
   – The final 3-D shape of the protein
      • Hydrophobic interactions with water


• Quaternary structure
   – Spatial arrangement of two or more polypeptide chains


• Chaperone proteins
   – Help new proteins fold correctly
                   Carbohydrates
• Monomers that make up the structural framework of
  cells and play a critical role in energy storage

  – A carbohydrate is any molecule that contains the elements
    C, H, and O in a 1:2:1 ratio

  – Carbohydrates vary in size
     • simple carbohydrates – made up of one or two monomers
         – Monosaccharides and disaccharides
     • complex carbohydrates – made up of polymers
         – Polysaccharides
                   Carbohydrates
• Polysaccharides
  – Used for energy storage
     • Large molecules insoluble, so stored
     • Plants store energy in starch
     • Animals store energy in glycogen


  – Used for structural support
     • Cellulose
     • Chitin
                         Lipids
• Lipids – fats and other molecules that are not soluble
  in water
   – Long term energy storage
   – Non-polar molecules
   – Many varieties
      •   fats
      •   oils
      •   steroids
      •   rubber
      •   waxes
      •   pigments
                            Lipids
•    Fats are converted from glucose for long-
     term energy storage

    – fats have two subunits
           1. fatty acids
           2. glycerol


    – fatty acids: chains of C and H atoms, known as
      hydrocarbons
       •   chain ends in a carboxyl (-COOH) group
                             Lipids




Because there are 3 fatty acids attached to a glycerol, another
name for a fat is triglyceride
                        Lipids
• Fatty acids have different chemical properties due to
  the number of hydrogens that are attached to the
  non-carboxyl carbons

   – Saturated: the maximum number of hydrogens are
     attached

   – Unsaturated: there are fewer than the maximum attached
Saturated and Unsaturated fats
                               Lipids
• Biological membranes involve lipids
    – phospholipids make up the two layers of the membrane
    – cholesterol is embedded within the membrane



Figure 4.16 Lipids are a key component of biological membranes

								
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