Lecture Notes: Organic Molecules and Organisms

Overview

• Focus on biochemistry, specifically organic molecules and their functions in organisms
• Four major biomolecules: Proteins, Nucleic Acids, Carbohydrates, and Lipids

Proteins

• Composition: Polymers made of amino acids
• Functions:
  • Muscle contraction
  • Hormones
  • Enzyme activity (catalysis)
  • Storage, growth, repair
• Structure:
  • Unfolded proteins are non-functional
  • Functional only when properly folded
  • Composed of a polypeptide chain (amino acids connected)
• Amino Acids:
  • 20 types: 9 essential (must be consumed), 11 non-essential (produced by the body)
  • Structure:
    • Alpha Carbon: Chiral center with four different groups
    • Amino group
    • Carboxyl group
    • R group (varies between amino acids)
• Polypeptide Terminology:
  • Dipeptide: Two amino acids
  • Tripeptide: Three amino acids
  • Polypeptide: More than ten amino acids
• Peptide Bond: Connects carboxyl group of one amino acid to the amino group of another
• Reading Polypeptide Chains: From N-terminal (amino group) to C-terminal (carboxyl group)
• Protein Structure Levels:
  • Primary: Sequence of amino acids
  • Secondary: Alpha helices, beta-pleated sheets, loops
  • Tertiary: 3D structure
  • Quaternary: Multiple polypeptides

Nucleic Acids

• Types: DNA (double-stranded), RNA (single-stranded)
• Monomers: Nucleotides
• DNA Structure:
  • Double helix with a sugar-phosphate backbone
  • Base pairs connected by hydrogen bonds
• Nucleotide Components:
  • Pentose Sugar: Ribose (RNA), Deoxyribose (DNA)
  • Nitrogenous Base:
    • Purines (Adenine, Guanine)
    • Pyrimidines (Thymine, Cytosine, Uracil)
  • Phosphate Group: Can be mono, di, or tri-phosphate
• Central Dogma: Replication, transcription, translation (to be discussed further)

Carbohydrates

• Composition: Carbon, hydrogen, oxygen
• Monomer: Monosaccharide
• Functions: Energy (ATP production), energy storage (glycogen)
• Monosaccharides:
  • Hexose: Six carbon sugars (e.g. glucose)
  • Functional Groups:
    • Carbonyl: Aldehyde (terminal), Ketone (internal)
    • Hydroxyl: Alcohol group
• Carbohydrate Forms:
  • Disaccharides: Two monosaccharides (sucrose, lactose, maltose)
  • Polysaccharides: Multiple monosaccharides (cellulose, starch, glycogen)
  • Can form linear or branched chains

Lipids

• General: Diverse group, insoluble in water
• Types:
  • Fatty Acids: Hydrocarbon tail, carboxyl group
  • Saturated: No double bonds (more hydrogens)
  • Unsaturated: One or more double bonds
• Functions:
  • Cell membrane component
  • Energy storage
  • Signalling, insulation
• Examples: Fats, oils

Next Lecture

• Focus on the role of enzymes in living organisms