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A3P Lecture Notes Review

A3P Lecture Notes

Organic vs. Inorganic Molecules

Organic Molecules

  • Definition: Molecules that contain one or more carbon atoms covalently bonded to hydrogen atoms.
    • They are made up of covalent bonds and must contain both carbon and hydrogen.
  • Carbon's Bonding Properties: Carbon atoms readily form covalent bonds with each other, as well as with hydrogen.
  • Structure: Organic molecules typically have a chain-like or ring-like structure of carbon atoms.
  • Other Common Elements: Besides carbon and hydrogen, organic molecules commonly contain oxygen, nitrogen, and/or sulfur.
  • Representation: Can be drawn as stick figures or using zig-zag shapes.
    • In zig-zag or geometric shapes, the corners represent carbon atoms.
    • Example: Ethanol (H-C-C-O-H) could be visualized using a zig-zag line where each corner is a carbon.

Inorganic Molecules

  • Definition: Molecules that do not contain carbon atoms covalently bonded to hydrogen atoms.

Biochemistry

  • Definition: The study of organic molecules.
  • Four Basic Types of Organic Molecules in Living Things:
    1. Carbohydrates
    2. Lipids
    3. Proteins
    4. Nucleic acids

Carbohydrates (aka "Carbs")

  • Composition: Molecules made up of carbons covalently bound.
  • Functions:
    • Fuel molecules (primary energy source).
    • Structural materials (e.g., in plants).
  • Includes: Sugars, starches, and fibers.

A. Monosaccharides ("Simple Sugar")

  • Structure: Composed of a single ring of carbons.
  • Examples:
    • Glucose: Known as "blood sugar."
    • Fructose: Known as "fruit sugar."
    • Galactose: Found in milk.

B. Disaccharides ("Simple Sugar")

  • Structure: Made up of two carbon rings bound together, specifically two monosaccharides covalently bound together.
  • Examples:
    • Sucrose: Known as "table sugar" or "cane sugar." Composed of glucose and fructose.
    • Lactose: Known as "milk sugar." Composed of glucose and galactose.
    • Maltose: Known as "malt sugar." Composed of glucose and glucose.

C. Polysaccharides ("Complex Carbohydrates")

  • Definition: Complex carbohydrates, including starches and fibers.
  • Structure: Made up of three or more monosaccharides bound together, typically hundreds of monosaccharides.
  • Functions: Primarily structural molecules.
  • Examples:
    • Glycogen: "Animal starch." Primarily a storage polysaccharide in animals.
    • Amylose: "Plant starch" or "corn starch." Found in plants, particularly in stems and seeds, serving as a structural component for energy storage.
    • Cellulose: "Plant fiber." A major structural component in plant cell walls and found in materials like cotton.

Lipids

  • Functions:
    • Fuel molecules (long-term energy storage).
    • Structural molecules (e.g., cell membranes).
    • Hormones.
  • Three Basic Types:
    1. Triglycerides
    2. Phospholipids
    3. Steroids

A. Triglycerides ("Fat")

  • Properties: "Fat molecules," which are hydrophobic (water-fearing).
  • Function: Primarily function as fuel molecules.
  • Composition: Made up of three carbon molecules called "glycerol" linked to three chains of carbons called "fatty acids."
    • Structure Visualization: A glycerol backbone (H-C-OH at three positions) connected to three long fatty acid chains.
Types of Fatty Acids
  1. Saturated Fatty Acids:
    • Structure: Have a straight carbon chain (e.g., C-C-C-C).
  2. Unsaturated Fatty Acids:
    • Structure: Have a carbon chain with one or more kinks or bends, typically due to double bonds (e.g., C-C=C-C).
  3. Trans Fatty Acids:
    • Structure: Possess an abnormal or unnatural kink/bend in their carbon chain.
Three Basic Triglyceride Types (Based on Fatty Acid Composition)
  • a. Saturated Fats:
    • Composition: Triglycerides with three saturated fatty acids.
    • Physical State: Solid at room temperature.
    • Sources: Abundant in meat, coconut oil, butter.
    • Health Implications: Consumption is linked to heart disease, stroke, obesity, and cancer. Considered an "unhealthy type" of fat.
  • b. Unsaturated Fats:
    • Composition: Triglycerides with at least one unsaturated fatty acid.
    • Physical State: Liquid at room temperature, commonly referred to as "oils."
    • Sources: Examples include vegetable oil, olive oil, and canola oil.
    • Health Implications: Considered a "healthy type of fat."
  • c. Trans Fats:
    • Composition: Triglycerides with at least one trans fatty acid.
    • Physical State: Generally liquid at room temperature.
    • Formation: Form when fat is heated at high temperatures, often as an unwanted byproduct during industrial food processing.
      • Example: Occurs when margarine and shortening are made in a food lab.
    • Health Implications: Considered the "unhealthiest fat."

B. Phospholipids

  • Functions:
    • Structural molecules.
    • Main molecules that form cell membranes (the outer structures of cells).
  • Composition: Made up of a glycerol molecule linked to two fatty acids AND a phosphate molecule (a molecule containing a phosphorus atom).
  • Nature: These are amphiphillic (or amphipathic) molecules.
    • This means they have two distinct parts:
      • A hydrophilic head (the phosphate group), which is attracted to water.
      • Two hydrophobic tails (the fatty acid chains), which repel water.
Behavior of Phospholipids in Water
  • When phospholipids are mixed with water, they spontaneously arrange to create microscopic spheres or bilayers.
  • Phospholipid Bilayer (aka "Lipid Bilayer"):
    • The wall of these structures (like cell membranes) is made up of two layers of phospholipids.
    • Orientation: The hydrophilic (water-attracting) heads orient outwards, dissolving in the surrounding water.
    • The hydrophobic (water-repelling) tails orient inwards, facing each other and away from the water, forming a barrier.
  • Analogy to Soap/Detergent Molecules:
    • Soap and detergent molecules are structurally similar to phospholipids.
    • They also possess a hydrophilic head and one to two hydrophobic tails, allowing them to interact with both water and fats/oils.