Overview
This lecture introduces the four major classes of organic molecules, their monomers, functions, key examples, and related concepts central to biochemistry.
Major Organic Molecules
- The four organic molecules are carbohydrates, lipids, proteins, and nucleic acids.
- Carbohydrates are made of monosaccharide monomers.
- Lipids are made of fatty acids and glycerol.
- Proteins are made of amino acid monomers.
- Nucleic acids are made of nucleotide monomers.
Functions and Examples
- Carbohydrates provide short-term energy and structure (e.g., glucose and fructose).
- Lipids offer long-term energy storage, insulation, and form cell membranes (e.g., fats, oils, waxes, steroids).
- Proteins lower activation energy, support movement, fight infection, and provide structure/transport (e.g., meat).
- Nucleic acids store and transmit genetic information (DNA and RNA).
Structures and Bonds
- Amino acids are linked by peptide bonds to form polypeptide chains.
- Nucleotides are building blocks of DNA and RNA.
- Triglyceride is made of glycerol and three fatty acid chains.
- Peptide bonds connect amino acids.
Enzymes and Chemical Reactions
- Enzymes are proteins that speed up reactions by lowering activation energy.
- The substrate binds to the enzyme’s active site.
- High temperature can denature enzymes, changing their shape.
- Rate of reaction is impacted by pH and temperature.
- The Lock and Key model describes enzyme specificity.
Key Biochemical Concepts
- Dehydration synthesis joins molecules by removing water.
- Reactants (substrates) turn into products in chemical reactions.
- Buffers regulate pH by adding or removing hydrogen ions.
- Indicators such as Benedict’s (monosaccharides) and Iodine (starch) test for specific biomolecules.
Biological Molecule Examples
- Cellulose (plant cell wall), chitin (insect exoskeleton), starch (plant energy), glycogen (animal energy).
- Saturated fats are straight and unhealthy (e.g., butter); unsaturated fats are healthier (e.g., oils).
Miscellaneous Biological Processes
- Homeostasis means stable internal balance.
- Autotrophs make their own food; heterotrophs must eat to survive.
- Growth involves increase in size and form.
- Respiration can be aerobic or anaerobic.
- Reproduction is either sexual or asexual.
Key Terms & Definitions
- Monomer — small molecule that is a building block of polymers.
- Polypeptide — chain of amino acids.
- Enzyme — protein that speeds up chemical reactions.
- Substrate — reactant an enzyme acts upon.
- Activation Energy — energy needed to start a reaction.
- Active Site — region on enzyme where substrate binds.
- Dehydration Synthesis — reaction joining molecules by removing water.
- Denatured — altered enzyme shape due to heat.
- Buffer — maintains pH balance.
- Lock and Key — enzyme specificity model.
Action Items / Next Steps
- Practice identifying organic molecules and their functions.
- Memorize monomers and examples for each macromolecule.
- Review enzyme function and the impact of environmental changes.