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Building Blocks of Life . An Introduction. Carbon is unparalleled in its ability to form large, complex, and diverse molecules Proteins, DNA, carbohydrates, and other molecules that distinguish living matter are all composed of carbon compounds. Carbon—The Backbone of Biological Molecules.

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Building Blocks of Life


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carbon the backbone of biological molecules

Carbon is unparalleled in its ability to form large, complex, and diverse molecules

  • Proteins, DNA, carbohydrates, and other molecules that distinguish living matter are all composed of carbon compounds
Carbon—The Backbone of Biological Molecules
carbon atoms can form diverse molecules by bonding to four other atoms

Electron configuration determines the kinds and number of bonds an atom will form with other atoms

  • With four valence electrons, carbon can form four covalent bonds with a variety of atoms
    • makes large, complex molecules possible
Carbon atoms can form diverse molecules by bonding to four other atoms
slide4

The valences of carbon and its most frequent partners (hydrogen, oxygen, and nitrogen) are the “building code” that governs the architecture of living molecules

macromolecules

Within cells, small organic molecules are joined together to form larger molecules

  • Macromolecules are large molecules composed of thousands of covalently connected atoms
Macromolecules
polymers built from monomers

Monomers build polymers linked together by covalent bonds

  • Three of the four classes of life’s organic molecules are polymers:
    • Carbohydrates
    • Proteins
    • Nucleic acids
    • Lipids
polymers built from monomers
the synthesis and breakdown of polymers

Monomers form larger molecules by condensation reactions called dehydration reactions

  • Polymers are disassembled to monomers by hydrolysis, a reaction that is essentially the reverse of the dehydration reaction
The Synthesis and Breakdown of Polymers
slide8

Short polymer

Unlinked monomer

Dehydration removes a water

molecule, forming a new bond

Longer polymer

Dehydration reaction in the synthesis of a polymer

Hydrolysis adds a water

molecule, breaking a bond

Hydrolysis of a polymer

carbohydrates

Sugars and sugar polymers

  • Monosaccharides
    • Simple sugars
    • glucose

Carbonyl group

Hydroxyl group

Carbohydrates
carbohydrates1

Disaccharides

    • 2 or more monosaccharides joined by glycosidic linkage, covalent bond by dehydration reaction
    • Glucose + fructose sucrose
Carbohydrates
carbohydrates2

Storage

    • Plant starch
    • Stored energy can be broken down by hydrolysis into glucose
    • Animal polysaccharide
      • Glycogen
        • Stored in liver and muscles
        • Used for short term energy
Carbohydrates
carbohydrates3

Structure

    • Cellulose: cell walls
      • Requires an enzyme for animals to break it down
    • Chitin: exoskeleton of arthropods and fungi
Carbohydrates
lipids

Fats, oils, waxes

    • Mix poorly with water
    • Fats
      • Large molecules of glycerol and fatty acid chains connected by dehydration
Lipids
lipids1

Cell Membranes

    • Phospholipid bi-layer
Lipids
proteins

Polymer of amino acids called polypeptides

  • Functions
    • Enzymes
    • Storage of amino acids
    • Hormones
    • Motor
    • Defense
    • Transport
    • Receptors for chemical stimuli
    • structure
Proteins
proteins1

Amino acids

    • 20 amino acids from 1000’s of proteins
    • Side chains “R” determines the properties
      • Hydrophillic:polar
      • Hydrophobic: non polar
      • Hydrophillic: electric charge
Proteins
proteins2

Structure

      • Linear chain
Proteins
proteins3

    • Alpha helix: hair
    • β pleated sheets: spider web
    • Held together by hydrogen bonds between amino groups
Proteins
proteins4

    • Interactions between side chains “R”
      • Hydrogen bonds
      • Ionic bonds
      • Disulfide bonds
      • Van der Waals
Proteins
proteins5

    • Aggregation of polypeptide subunits
      • Collagen
      • hemoglobin
Proteins
proteins6

Denaturation

    • Weak chemical bonds and interactions can be destroyed
      • Heat
      • pH
Proteins