Lecture Notes: Molecules of Life - Organic Compounds

Overview

• Organic compounds: Molecules containing carbon.
• Origin of the term "organic": Initially thought to be made only by organisms.
• Carbon's unique ability to form large and complex molecules due to its four covalent bonds.

Vocabulary

• Organic compounds
• Hydrocarbons: Molecules consisting only of carbon and hydrogen.
• Isomers: Compounds with the same chemical formula but different structural arrangements.
• Functional groups: Specific groups of atoms within molecules that determine chemical properties.

Carbon Characteristics

• Can form up to four covalent bonds.
• Strong covalent bonds create stable compounds.
• Forms chains or rings with other carbon atoms.
• Hydrocarbons: Contain only carbon and hydrogen (e.g., methane, ethane).

Types of Bonds

• Single bonds: One shared pair of electrons.
• Double bonds: Two shared pairs of electrons.
• Triple bonds: Three shared pairs of electrons.

Types of Hydrocarbons

• Methane
• Ethane
• Ethene: Double bond variant.
• Ethyne: Triple bond variant.

Structural Variations

• Chains: Straight chains (e.g., ethane).
• Branches: Branched chains (e.g., isobutane).
• Rings: Ring structures can have single or double bonds.

Isomers

• Same formula, different structure.
• Example: Butane (straight) vs. Isobutane (branched).

Functional Groups

• Affect a compound's function.
• Polar: Hydrophilic, water-soluble.
• Non-polar: Hydrophobic.

Key Functional Groups

• Hydroxyl group (OH): Found in alcohols and sugars.
• Carbonyl group (C=O): Aldehyde (end of chain) or Ketone (middle of chain).
• Carboxyl group (COOH): Found in acids; ionizable, donates hydrogen ion.
• Amino group (NH2): Acts as a base; can pick up hydrogen ions.
• Phosphate group (PO4): Important in energy transfer (e.g., ATP).
• Methyl group (CH3): Non-polar, forms methylated compounds.

Importance of Functional Groups

• Change the function of molecules.
• Example: Estradiol vs. Testosterone.

Classes of Organic Molecules

• Carbohydrates
• Lipids
• Proteins
• Nucleic Acids

Macromolecules

• Made of subunits called monomers.
• Monomers form Polymers through dehydration synthesis.

Dehydration Synthesis

• Removing water (H2O) to form covalent bonds.

Hydrolysis

• Adding water to break bonds.
• Essential in digestion.

Conclusion

• Organic molecules utilize about 40-50 common parts.
• Diversity in organisms is due to the variety of organic compounds.

Next Lesson

• Focused on sugars.