1. The Scope of "Life"
2. More on the Origin of Life
3. The Organism and the Cell
4. Proteinsâ€”How Things Get Done in the Cell
5. Which Molecule Holds the Code?
6. The Double Helix
7. The Nuts and Bolts of Replicating DNA
8. The Central Dogma
9. The Genetic Code
10. From DNA to RNA
Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy. Biology is a vast subject containing many subdivisions, topics, and disciplines. Among the most important topics are five unifying principles that can be said to be the fundamental axioms of modern biology:
Cells are the basic unit of life
New species and inherited traits are the product of evolution
Genes are the basic unit of heredity
An organism regulates its internal environment to maintain a stable and constant condition
Living organisms consume and transform energy.
Subdisciplines of biology are recognized on the basis of the scale at which organisms are studied and the methods used to study them: biochemistry examines the rudimentary chemistry of life; molecular biology studies the complex interactions of systems of biological molecules; cellular biology examines the basic building block of all life, the cell; physiology examines the physical and chemical functions of the tissues, organs, and organ systems of an organism; and ecology examines how various organisms interact and associate with their environment.