Organic Chemistry and Biological Molecules

Introduction

This study guide covers foundational concepts in organic chemistry as they relate to general biology, including definitions, major atom types, functional groups, and the structure and function of ATP. Understanding these topics is essential for grasping the chemical basis of biological processes.

Definitions and Key Terms

• Organic Chemistry: The branch of chemistry that studies carbon-containing compounds, especially those found in living organisms.

• Hydrocarbon: Organic molecules consisting entirely of carbon and hydrogen atoms. Examples include methane (CH4) and ethane (C2H6).

• Isomer: Molecules with the same molecular formula but different structural arrangements. Types include structural isomers, cis-trans isomers, and enantiomers.

Major Atoms in Organic Compounds

Organic molecules are primarily composed of six major atoms:

• Carbon (C)

• Hydrogen (H)

• Oxygen (O)

• Nitrogen (N)

• Phosphorus (P)

• Sulfur (S)

These atoms combine in various ways to form the diverse molecules essential for life.

Valence Numbers

The valence number of an atom is the number of electrons it can share, lose, or gain to form chemical bonds.

• Carbon: 4

• Hydrogen: 1

• Oxygen: 2

• Nitrogen: 3

Valence numbers determine how atoms bond and the shapes of molecules.

Functional Groups

Functional groups are specific groups of atoms within molecules that confer particular chemical properties. They are critical in determining the behavior of organic molecules.

• Importance: Functional groups participate in chemical reactions, influence molecular polarity, and affect biological activity.

The Seven Major Functional Groups

Isomers: Types and Significance

• Structural Isomers: Differ in covalent arrangement of atoms.

• Cis-Trans Isomers: Differ in spatial arrangement around a double bond.

• Enantiomers: Mirror-image isomers, important in pharmaceuticals.

Isomerism increases molecular diversity and affects biological function.

Functional Groups: Properties and Examples

• Hydroxyl: Found in sugars and alcohols; increases solubility in water.

• Carbonyl: Found in sugars; determines whether a sugar is an aldose or ketose.

• Carboxyl: Found in amino acids and fatty acids; acts as an acid.

• Amino: Found in amino acids; acts as a base.

• Sulfhydryl: Found in cysteine; forms disulfide bridges in proteins.

• Phosphate: Found in nucleotides (e.g., ATP); involved in energy transfer.

• Methyl: Found in DNA and proteins; affects gene expression.

Functional groups contribute to molecular polarity, reactivity, and biological roles.

Macromolecules and Functional Groups

• Proteins: Amino and carboxyl groups; sulfhydryl groups stabilize structure.

• Nucleic Acids: Phosphate groups; nitrogenous bases.

• Lipids: Carboxyl and methyl groups.

• Carbohydrates: Hydroxyl and carbonyl groups.

Functional groups determine the chemical properties and biological functions of macromolecules.

ATP and ADP: Structure and Function

• ATP (Adenosine Triphosphate): The primary energy carrier in cells. Composed of adenine, ribose, and three phosphate groups.

• ADP (Adenosine Diphosphate): Formed when ATP loses one phosphate group; can be converted back to ATP.

• Difference: ATP has three phosphate groups; ADP has two. The removal of a phosphate releases energy for cellular processes.

General Structure of ATP:

• Adenine (nitrogenous base)

• Ribose (five-carbon sugar)

• Three phosphate groups

ATP Hydrolysis Equation:

ATP hydrolysis provides energy for cellular work, such as muscle contraction and active transport.

Summary Table: ATP vs. ADP

Additional info:

• Functional groups are essential for the structure and function of biological macromolecules.

• Isomerism is a key concept in organic chemistry, affecting molecular function and biological activity.

• ATP is universally used by cells to store and transfer energy.