Organic Compounds & Carbon Chemistry

Properties of Carbon

Carbon is a unique element that forms the backbone of organic molecules essential for life. Its ability to form four covalent bonds allows for the creation of large, complex molecules with diverse structures and functions.

• Carbon forms 4 covalent bonds, enabling the construction of complex, large molecules.

• Organic compounds: Molecules based on carbon, usually containing hydrogen atoms in addition to carbon.

• Carbon skeletons can vary in length, branching, rings, and the presence of double bonds, contributing to molecular diversity.

• Isomers: Compounds with the same formula but different structures (e.g., butane vs. isobutane). Isomer diversity increases the variety of organic molecules and their properties.

Additional info: The versatility of carbon is fundamental to the chemistry of life, as it allows for the formation of a wide range of biological molecules.

Functional Groups

Functional groups are specific configurations of atoms attached to carbon skeletons that participate in chemical reactions and influence molecular properties.

• Functional groups affect a molecule's function by participating in chemical reactions, determining properties and reactivity.

• These groups are often polar, making compounds hydrophilic (water-loving) and soluble in water.

• Key functional groups:

  • Hydroxyl (-OH): Found in alcohols; polar.

  • Carbonyl (C=O): Found in aldehydes and ketones.

  • Carboxyl (-COOH): Characteristic of carboxylic acids; acts as an acid.

  • Amino (-NH2): Found in amino acids; acts as a base.

  • Phosphate (-PO4): Involved in energy transfer (e.g., ATP).

  • Methyl (-CH3): Nonpolar; affects gene expression and molecular shape.

Macromolecules & Polymers

Classes of Biological Macromolecules

Cells contain four main classes of macromolecules, each with distinct structures and functions.

• Carbohydrates

• Lipids

• Proteins

• Nucleic acids

Macromolecules are often polymers, large molecules made by joining smaller subunits called monomers.

• Polymers: Long molecules consisting of many similar building blocks (monomers) joined together.

• Monomers: Smaller molecules that serve as the building blocks of polymers.

• Cells link monomers together to form polymers by dehydration reactions (removal of water).

• Polymers are broken down by hydrolysis (addition of water).

Equation for Dehydration Reaction:

Equation for Hydrolysis:

Carbohydrates

Monosaccharides

Monosaccharides are simple sugars and the monomers of carbohydrates. They serve as the main fuel molecules for cellular work.

• General formula: CH2O

• Examples: Glucose, fructose

• Monosaccharides form rings in aqueous solutions.

• Glucose and fructose are isomers, differing only in the arrangement of atoms.

• Sugars can be hooked together by dehydration reactions to form more complex sugars and polysaccharides.

Formula for a monosaccharide with three carbons:

Polysaccharides

Polysaccharides are macromolecules consisting of hundreds to thousands of monosaccharides linked together by dehydration reactions. They function as storage molecules or structural compounds.

• Starch: Storage polysaccharide in plants, consists of long chains of glucose monomers. Major source of energy in human diet.

• Glycogen: Highly branched storage polysaccharide in animals. Stored in liver and muscle cells.

• Cellulose: Most abundant organic compound on earth; major component of plant cell walls. Provides structural support and is a source of dietary fiber.

Lipids

Types and Properties

Lipids are a diverse group of hydrophobic molecules, including fats, phospholipids, and steroids. They differ from carbohydrates, proteins, and nucleic acids in that they are not polymers.

• Fats (triglycerides): Large lipid molecules made from glycerol and fatty acids. Main function is energy storage.

• Phospholipids: Major component of cell membranes.

• Steroids: Lipids with a structure of four fused rings (e.g., cholesterol).

Fatty Acids

• Saturated fatty acids: No double bonds in hydrocarbon chain; maximum number of hydrogen atoms attached. Solid at room temperature (e.g., animal fats).

• Unsaturated fatty acids: One or more double bonds; fewer hydrogen atoms attached. Liquid at room temperature (e.g., plant oils).

Additional info: Hydrogenation can convert unsaturated fats to saturated fats, producing trans fats, which have health risks.

Proteins

Structure and Function

Proteins are polymers made from amino acid monomers. They perform a wide variety of functions in cells, including catalysis, structural support, transport, and regulation.

• Amino acids: Building blocks of proteins; each has a central carbon atom bonded to an amino group, carboxyl group, hydrogen atom, and a variable side chain (R group).

• Polypeptides: Chains of amino acids linked by peptide bonds.

• Protein shape determines its function; shape is determined by the sequence of amino acids and interactions among them.

Equation for Peptide Bond Formation:

Nucleic Acids

DNA and RNA

Nucleic acids are polymers made from nucleotide monomers. They store and transmit genetic information.

• DNA (deoxyribonucleic acid): Stores genetic information; built from four kinds of nucleotides.

• RNA (ribonucleic acid): Involved in protein synthesis and gene regulation.

• Nucleotides consist of a sugar, phosphate group, and nitrogenous base.

Additional info: DNA and RNA differ in their sugars and nitrogenous bases, and DNA is typically double-stranded while RNA is single-stranded.