Molecules of Life Quiz

Molecules of Life Overview

• Cells are primarily composed of water and carbon-based organic compounds.
• Organic compounds contain carbon; simplest form is hydrocarbons (only carbon and hydrogen).
• Four major classes of organic molecules: carbohydrates, lipids, proteins, and nucleic acids.

Organic Molecules Characteristics

• Known as macromolecules due to large size.
• Also referred to as polymers, constructed from smaller subunits called monomers.
• Monomers serve as building blocks for larger polymers.

Carbohydrates

• Main source of energy for cellular functions.
• Building blocks are simple sugars known as monosaccharides.
• Three classes include:
  • Monosaccharides: Simple sugars (e.g., glucose, fructose, galactose).
  • Disaccharides: Formed from two monosaccharides via dehydration reactions (e.g., sucrose, maltose, lactose).
  • Polysaccharides: Long chain polymers made of monosaccharides (e.g., starch, glycogen, cellulose).

Lipids

• Hydrophobic compounds that do not mix well with water.
• Key types include fats, phospholipids, and steroids.
• Fats serve mainly as energy storage, composed of glycerol and fatty acids, typically in triglyceride form.
• Phospholipids form cell membranes, consisting of two fatty acids and a phosphate group, creating hydrophobic tails and hydrophilic heads.
• Steroids consist of fused ring structures; cholesterol is an important steroid that supports cell membrane structure and synthesizes sex hormones.

Proteins

• Polymers made from amino acid monomers.
• Composed of 20 different amino acids linked by peptide bonds, creating long protein chains.
• Amino acids consist of an amino group, a carboxyl group, and a variable side chain (R group).
• Functions encompass:
  • Structural components (e.g., actin, myosin in muscles).
  • Defensive roles (e.g., antibodies).
  • Transport functions (e.g., hemoglobin).