Carbon and the Molecular Diversity of Life: Study Notes for General Biology

Overview: Carbon Compounds and Life

Introduction to Organic Compounds

Living organisms are primarily composed of water and carbon-based compounds. The study of these compounds is essential for understanding biological processes.

• Organic compound: A compound that contains carbon.

• Water and carbon-based compounds are the main constituents of living matter.

Organic Chemistry

Properties of Carbon

Carbon is fundamental to life due to its unique chemical properties, which allow it to form a wide variety of stable compounds.

• Carbon atoms have 4 valence electrons, enabling them to form up to four covalent bonds with other atoms.

• This bonding capacity allows carbon to create complex molecules by bonding to four different atoms simultaneously.

Hydrocarbons

Hydrocarbons are the simplest organic molecules, consisting only of carbon and hydrogen. They serve as the backbone for many biological molecules.

• Hydrocarbons: Organic molecules made exclusively of carbon and hydrogen.

• Many biological molecules, such as fats, contain hydrocarbon components.

• Hydrocarbons can undergo reactions that release significant amounts of energy, making them important energy sources.

Structural Diversity of Hydrocarbons

Hydrocarbons vary in structure, which affects their chemical properties and biological roles.

• Length: Hydrocarbon chains can be short (e.g., methane) or long (e.g., propane).

• Branching: Chains may be straight or branched (e.g., isobutane).

• Double bond position: Double bonds can occur at different locations (e.g., 1-butene vs. 2-butene).

• Presence of rings: Some hydrocarbons form rings (e.g., cyclohexane, benzene).

Table: Hydrocarbon Structures

Name	Molecular Formula	Structural Formula	Ball-and-Stick Model	Space-Filling Model
Methane	CH4	H | C | H	Ball-and-stick representation	Space-filling representation
Ethane	C2H6	H-C-C-H	Ball-and-stick representation	Space-filling representation
Ethene (ethylene)	C2H4	H2C=CH2	Ball-and-stick representation	Space-filling representation

"Building Code" of Organic Molecules

The architecture of molecules in living organisms is governed by the types and numbers of atoms present.

• Carbon (C)

• Hydrogen (H)

• Oxygen (O)

• Nitrogen (N)

• These elements form the backbone of most biological molecules.

Valence Electrons of Key Elements

• Hydrogen: 1 valence electron

• Oxygen: 6 valence electrons

• Nitrogen: 5 valence electrons

• Carbon: 4 valence electrons

Chemical Groups Most Important to Life

Functional Groups

Functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules.

• Functional groups: Components of organic molecules most commonly involved in chemical reactions.

• They determine the properties and reactivity of organic molecules.

*Additional info: Functional groups include hydroxyl, carbonyl, carboxyl, amino, sulfhydryl, phosphate, and methyl groups. These groups are essential for the structure and function of biomolecules such as carbohydrates, proteins, lipids, and nucleic acids.*