BIOL 1100-01 Biological Science for Non-Majors Module 1 Study Guide

Module 1: Important Biological Macromolecules

Lipids

  • Lipids represent a diverse group of hydrophobic molecules.
  • Lipids are unique among large biological molecules as they do not include true polymers.
  • The unifying feature of lipids is their poor mixing with water, exhibiting hydrophobic properties.
  • Composition: Consist mostly of hydrocarbon regions.
  • Biologically important lipids include:
    • Fats
    • Phospholipids
    • Steroids

Fats

  • Fats are comprised of two types of smaller molecules:
    • Glycerol: A three-carbon alcohol with one hydroxyl group (–OH) attached to each carbon.
    • Fatty Acids: Comprise a carboxyl group (–COOH) attached to a long carbon skeleton.
Structure of Fats
  • Fats are formed when three fatty acids are joined to glycerol by an ester linkage, resulting in a triacylglycerol (triglyceride).
  • Separation from water occurs because water molecules engage in hydrogen bonding with each other, excluding fats.
  • The fatty acids that compose a fat molecule may be:
    • All the same
    • A mix of two or three different types
Dehydration Synthesis
  • The synthesis of fats involves dehydration reactions whereby one water molecule is removed for each fatty acid that is joined to the glycerol.
  • Diagrammatic representation includes the formation of an ester linkage.
Visual Representation of Fatty Acids and Glycerol
  • Diagram (Figure 5.9):
    • Illustrates the attachment of a fatty acid (e.g., palmitic acid) to glycerol, showcasing ester linkage and water removal.

Fatty Acids

  • Fatty acids vary by:
    • Length (number of carbon atoms)
    • Number and locations of double bonds
  • Types of Fatty Acids:
    • Saturated Fatty Acids: Maximum number of hydrogen atoms, no double bonds.
    • Unsaturated Fatty Acids: One or more double bonds present.
Characteristics of Fatty Acids
  • Fats made from saturated fatty acids are termed saturated fats and are usually solid at room temperature; most animal fats fall into this category.
  • Unsaturated fats (oils) are composed largely of unsaturated fatty acids and remain liquid at room temperature; generally found in plant and fish fats.
Structural Representation
  • Diagram (Figure 5.10):
    • Illustrates the structural formula for saturated fats and unsaturated fats:
      • Saturated Fat: Space-filling model of stearic acid.
      • Unsaturated Fat: Structural formula and space-filling model of oleic acid, indicating a cis double bond which causes a bend in the structure.

Fats and Health

  • Diets high in saturated fats may increase the risk of cardiovascular disease due to plaque formation in arteries.
  • Hydrogenation: A method for converting unsaturated fats into saturated fats by adding hydrogen atoms, which may also result in trans fats possessing trans double bonds.
  • Trans fats potentially pose an even greater risk for cardiovascular disease than saturated fats.

Function of Fats

  • The principal function of fats is energy storage, wherein humans and mammals store long-term food reserves in adipose cells.
  • Adipose tissue serves to cushion vital organs and provide insulation for the body.

Phospholipids

  • A phospholipid comprises two fatty acids and a phosphate group attached to glycerol.
  • Characteristics:
    • The two fatty acid tails exhibit hydrophobic properties.
    • The phosphate group and its attachments form a hydrophilic (water-attracting) head.
Phospholipid Function
  • When phospholipids are added to water, they naturally self-assemble into double-layered structures known as bilayers.
  • In cellular structures, phospholipids arrange themselves into a bilayer where hydrophobic tails face the interior, creating a barrier between the cell and its external environment.

Steroids

  • Steroids are a class of lipids characterized by a carbon skeleton that consists of four fused rings.
  • Cholesterol is a notable type of steroid, serving as a vital component of animal cell membranes and acting as a precursor for the synthesis of other steroids.
  • High cholesterol levels in the blood are linked to an increased risk of cardiovascular disease.