Chapter 2: The Chemistry of Life – Chemical Level of Organization

Chapter 2: The Chemistry of Life

Introduction to the Chemical Level of Organization

The chemical level of organization is the foundational level in anatomy and physiology, focusing on the basic chemical principles that underlie all living systems. Understanding this level is essential for grasping how cells and tissues function in the human body.

• The Chemistry of Life refers to the study of atoms, molecules, and chemical reactions that form the basis of biological processes.

• This is considered the first living level in the hierarchy of biological organization.

• Key topics include atomic structure, chemical bonds, chemical reactions, pH, and the chemistry of major biomolecules.

Learning Objectives

• Relate basic concepts of chemistry (atomic structure, chemical bonds, chemical reactions, pH) to the cell and body.

• Explain the chemistry and functions of carbohydrates, lipids, proteins, and nucleic acids in biological systems.

Atomic Structure

Atoms and Subatomic Particles

Atoms are the smallest units of matter and the building blocks of all substances, living and non-living.

• Matter: Anything that has mass and occupies space (volume).

• Mass: The actual amount of substance present.

• Weight: The force of gravity acting on mass.

• Atoms consist of three major subatomic particles:

  • Protons: Positive charge, 1 mass unit

  • Neutrons: Neutral charge, 1 mass unit

  • Electrons: Negative charge, very low mass

• Atomic number: Number of protons in the nucleus

• Mass number: Number of protons plus neutrons

• In a neutral atom, number of protons equals number of electrons.

Classification of Matter

Types of Compounds

• Inorganic Compounds: Do not contain carbon-hydrogen bonds. Examples: water, salts, acids, bases.

• Organic Compounds: Contain carbon-hydrogen bonds. Examples: carbohydrates, lipids, proteins, nucleic acids, high energy compounds.

Key Table: Major Classes of Compounds

Inorganic Compounds	Organic Compounds
Water Salts Acids Bases	Carbohydrates Lipids Proteins Nucleic acids High energy compounds

Atoms: The Smallest Units of Matter

Definitions and Properties

• Atoms are the smallest units of matter that retain the properties of an element.

• All things, living and non-living, are made of matter.

• Matter is defined by its mass and volume.

Subatomic Particles and Their Charges

• Protons: Positive charge, 1 mass unit

• Neutrons: Neutral charge, 1 mass unit

• Electrons: Negative charge, very low mass

• Atomic number ($\text{Atomic number} = \text{Number of protons}$)

• Mass number ($\text{Mass number} = \text{Number of protons} + \text{Number of neutrons}$)

• Atoms are electrically neutral when the number of protons equals the number of electrons.

Key Questions for Review

• What are the major subatomic particles and their charges?

• How do atomic number and mass number relate to isotopes?

• Why are atoms electrically neutral?

• What are ions?

Summary Table: Subatomic Particles

Particle	Charge	Mass	Location
Proton	+1	1 mass unit	Nucleus
Neutron	0	1 mass unit	Nucleus
Electron	-1	~0 mass unit	Electron shell/orbit

Additional info: These notes provide foundational chemistry concepts essential for understanding cell structure and function in anatomy and physiology. Later sections (not shown here) would expand on chemical bonds, reactions, pH, and biomolecules.