Chapter 3: Water, Carbohydrates, Lipids, Proteins, Nucleic ... Lipids ! Proteins ! Nucleic Acids ....

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Transcript of Chapter 3: Water, Carbohydrates, Lipids, Proteins, Nucleic ... Lipids ! Proteins ! Nucleic Acids ....

  • Chapter 3: Water, Carbohydrates,

    Lipids, Proteins, Nucleic Acids

    Dr. Amy Rogers

  • • Human body is 2/3 water by weight • On Earth, life first appeared in water

    What is it about WATER???

  • Properties of Water

    n Solvent: Polar & charged solutes

    n Specific Heat: great insulator

    n Temperature/Density: Ice floats! n Surface Tension: Walk on water? Sure!

  • Water as a Solvent

    Hydrophilic: “water loving”

    interacts with water

    Polar or Ionic Solute

  • Hydrophobic molecules

    • Do not dissolve in water • Crucial for maintaining biological “compartments”

  • Water is a good insulator

    Imagine you are winter camping in the Rocky Mountains. To keep warm, you can take one of these items into your

    sleeping bag with you:

    Water bottle heated to 100oF vs.

    Aluminum brick heated to 100oF

  • Specific Heat:

    The amount of energy required to raise the temperature of a substance by 1o C

    Heat buffering by water maintains (relatively) stable

    temperatures on earth and in animals’ bodies

  • The important macromolecules for cells:

    n  Carbohydrates

    n  Lipids n  Proteins

    n  Nucleic Acids

  • Polymers

    n  Many complex organic molecules are polymers

    (large molecules made up of

    many similar or identical subunits)

  • Simple Carbohydrates

    n  Monosaccharides (Simple sugars) e.g, glucose, fructose, deoxyribose

    • Note ending of sugar names is usually - ose

  • Complex Carbohydrates

    n  Polysaccharides e.g., starch, glycogen, cellulose, chitin

    n Polymers of thousands of sugars

    n Bread, cereal, pasta

  • Complex Carbohydrates: Starch

    • Massive polymer of glucose • Energy storage in many plants

    • When energy is needed, starch is degraded back into glucose

  • Complex Carbohydrates: Glycogen

    • Main form of carbohydrate storage in animals

    • In humans, kept primarily in liver and muscle

  • Complex Carbohydrates: Cellulose

    • Rigid

    • Cell walls of many organisms:

    • Trees, cotton, grasses…

    • Easily the most abundant carbohydrate on earth!

    • Mammals cannot digest it

    • Major source of insoluble fiber

  • Lipids n  Fats, oils, cholesterol, hormones n  Made of C, H, O like carbohydrates but

    relatively much more H than O

    n Relatively insoluble in water

    n  Not all are polymers

  • Lipids

    n  Uses: n  Long-term energy storage n  Insulation n  Hormones n  Separation of biological compartments


  • Energy Storage

    n  Carbohydrates & Lipids are both used by cells to store energy for future use

  • Lipids (fats)

    n  All membranes are made of lipids n  Cell membrane, nuclear membrane

  • Proteins: Workers of the world, united

    n  Need something done? Call a protein!

    n About ½ dry weight of a cell

    n  Enzymes: mediate chemical reactions n  Messengers, transporters, defenders, movers, structure

    builders, poisons, communicators…….

  • Proteins are Polymers

    n  Proteins are long chains of smaller subunits called amino acids

    n  Like letters of the alphabet, they can be strung together in any sequence or length to create a spectacular variety of proteins

  • Amino Acids make polypeptides

  • Proteins: 3D is key

    n  A long straight chain of amino acids is energetically unstable: BONDS will form

    n  Polypeptides fold into a specific conformation

    n  Unique 3D shape of proteins is CRUCIAL for their function

  • Nucleotides & Nucleic Acids

    n  Subunit: nucleotides n  Nucleotide ATP is vital energy carrier n  You will learn much more about ATP soon

    Phosphate group

    Sugar “Base”: A, T, G, C

  • Nucleotides & Nucleic Acids

    n  Nucleotide polymer: Nucleic acid (DNA, RNA)

    n  Information molecule n  Blueprint for protein manufacture n  Cell’s “hard drive”