Lecture Notes: Organic Molecules and Functional Groups

Introduction to Organic Molecules

Definition: Organic molecules have carbon skeletons or backbones.
Not all molecules with carbon backbones are from living things, but many important biological molecules have carbon backbones.
A basic understanding of organic chemistry is essential for studying biology.

Role: Functional groups give molecules their unique properties.
Example: Alcohols, identified by an OH group (hydroxyl group).
- Isopropanol: Rubbing alcohol.
- Ethanol: Found in alcoholic beverages.
- Methanol: Known as wood alcohol; can cause blindness if ingested.

Major Functional Groups and Their Biological Importance:
- Alcohols: Found in lipids and carbohydrates.
- Aldehydes: Present in reducing sugars (e.g., glucose) and polysaccharides.
- Ketones: Important in metabolic intermediates.
- Methyl Groups: Involved in DNA methylation, affecting gene expression.
- Amino Groups: Found in proteins.
- Esters: Present in bacterial and eukaryotic plasma membranes.
- Ether Groups: Found in archaeal plasma membranes.
- Sulfur Groups (Sulfhydryl): Found in proteins and energy metabolism.
- Carboxyl Groups: Present in organic acids, lipids, and amino acids.
- Phosphate Groups: Crucial in nucleic acids and ATP (energy transfer).

Molecular Composition: Organic molecules often contain carbon, hydrogen, and oxygen.
Examples:
- Glucose: Broken down from starch during digestion.
- Ethanol: May be consumed in beverages.
- Ibuprofen: Used for pain relief.
Despite having the same elements (C, H, O), these molecules have different functions.

Small Organic Molecules: Can combine into larger macromolecules.
Macromolecules: Large biological molecules (polymers) composed of repeating units (monomers).
- Polymers: Large molecules made up of repeating subunits (e.g., polyester).
- Monomers: Small repeating molecules that form polymers.