Organic Molecules in Chemistry

Definition and Classification

Organic molecules are chemical compounds primarily composed of carbon atoms covalently bonded to hydrogen, oxygen, nitrogen, and other elements. They form the basis of living matter and are central to biochemistry and general chemistry.

• Organic molecules: Compounds with covalently linked carbon atoms.

• Hydrocarbons: Molecules made only of carbon and hydrogen atoms.

• CHNOPS: Acronym for the bulk elements in living systems: Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, Sulfur.

Example: Identifying organic molecules and hydrocarbons in molecular diagrams.

Carbon as a Building Block

Carbon's ability to form four covalent bonds makes it a versatile 'atomic building block' for a wide variety of molecules. The backbone of organic molecules can vary in:

• Length: Number of carbon atoms in a chain.

• Position of double bonds: Location of C=C bonds.

• Branch points: Where chains split.

• Ring forms: Cyclic structures.

Example: Variations in carbon backbones (linear, branched, ring).

Functional Groups

Definition and Importance

Functional groups are specific groups of atoms within molecules that are responsible for characteristic chemical reactions. They are commonly found attached to the carbon backbone and confer reactivity and properties to organic molecules.

• Common functional groups in biology:

  • Hydroxyl (-OH)

  • Carbonyl (C=O)

  • Carboxyl (-COOH)

  • Amino (-NH2)

  • Sulfhydryl (-SH)

  • Phosphate (-PO4)

  • Methyl (-CH3)

Example: Identifying functional groups in molecular structures.

Biomolecules: Classes and Structure

Main Classes of Biomolecules

Biomolecules are organic molecules essential for life. There are four primary classes:

• Carbohydrates

• Proteins

• Nucleic Acids

• Lipids

Example: Visual representations of each biomolecule class.

Monomers and Polymers

Monomers are small, repeating units that can be linked together to form polymers. The type of monomer determines the type of polymer and its biological function.

• Carbohydrate monomer: Monosaccharide

• Protein monomer: Amino acid

• Nucleic acid monomer: Nucleotide

Polymerization: Monomers are joined by covalent bonds to form polymers.

Polymer Formation and Breakdown

• Dehydration synthesis: Forms covalent bonds between monomers, releasing water ().

• Hydrolysis: Breaks covalent bonds in polymers by adding water.

Example: Formation and breakdown of polymers via dehydration and hydrolysis reactions.

Carbohydrates

Structure and Formula

Carbohydrates are carbon-based molecules hydrated with many hydroxyl groups (-OH). They are commonly referred to as sugars.

• General formula:

• Monosaccharides: Simple sugars (e.g., glucose, )

Example: Simple vs. complex carbohydrates.

Classes of Carbohydrates

• Monosaccharides: Single sugar units

• Oligosaccharides: 2–20 covalently linked monosaccharides

• Polysaccharides: Hundreds to thousands of monosaccharides linked

Formation and Breakdown of Polysaccharides

Polysaccharides are formed by linking monosaccharides via dehydration synthesis, creating glycosidic bonds. Hydrolysis breaks these bonds.

• Glycosidic bond: Covalent bond joining two monosaccharides

• Dehydration synthesis:

• Hydrolysis:

Example: Formation of maltose from two glucose molecules.

Carbohydrate Functions

Structural Support and Energy Storage

Carbohydrates serve two main functions in living organisms:

• Structural support: Building materials (e.g., cellulose in plants, chitin in insects)

• Energy storage: Short-term energy reserves (e.g., starch in plants, glycogen in animals)

Example: Comparison of polysaccharide functions in plants and animals.

Key Polysaccharides

• Cellulose: Structural polysaccharide in plants

• Chitin: Structural polysaccharide in insects and crustaceans

• Starch: Energy storage in plants

• Glycogen: Energy storage in animals

Example: Animal cells store energy as glycogen; plant cells store energy as starch.

Additional info: These notes expand on the original content by providing definitions, examples, and equations relevant to general chemistry and introductory biochemistry. The structure and function of organic molecules, especially carbohydrates, are foundational topics in college-level chemistry courses.