Biology : Cellular biology 

The term biology was coined in the late 1700s by the French naturalists Pierre-Antoine de Monet and Jean-Baptiste de Lamarck. It is the science of life: Of the composition and behavior of living things, of their interactions with each other and their environment.

• at the atomic and molecular scale, through molecular biology, biochemistry and genetics (study of organic molecules, their structures, properties and interactions)
• at the cellular scale, through cell biology
• at the multicellular scale, through physiology and histology
• at the level of the population of organisms, in population genetics
• on the multi-species scale of lineages, through systematics (comparison and classification of living organisms), anatomy, ontogeny, and ethology (behavior and adaptability)
• to the top of the scale, ecology (study of ecosystems, interactions between living organisms and their environment)

One the central, organizing concepts in biology is that all life has descended from a common origin though a process of evolution. Charles Darwin was the first to rigorously argue this idea, which he did with his proposal of natural selection as an evolutionary mechanism. The evolutionary history of a species, i.e., the characteristics of the species from which it descended, is called the phylogeny of the species; it is studied using methods of molecular biology by analyzing biopolymer sequences of genes and proteins, and by investigating ancient forms of life in paleontology. Various methodologies have been developed, including phylogenetics, phenetics, and cladistics. An evolutionary timeline outlining the major events in the evolution of life on Earth is available.

The classification of living things is called systematics, or taxonomy, and should reflect the evolutionary trees (phylogenetic trees) of the different organisms. Taxonomy piles up organisms in groups called taxa, while systematics seeks their relationships. The dominant system is called Linnaean taxonomy, which includes ranks and binomial nomenclature. How organisms are named is governed by international agreements such as the International Code of Botanical Nomenclature[?] (ICBN), the International Code of Zoological Nomenclature (ICZN), and the International Code of Nomenclature of Bacteria[?] (ICNB). A fourth Draft BioCode was published in 1997 in an attempt to standardize naming in the three areas, but it doesn't appear to have yet been formally adopted. The International Code of Virus Classification and Nomenclature[?] (ICVCN) remains outside the BioCode.

Traditionally, living things were divided into five kingdoms:

Monera -- Protista -- Fungi -- Plantae -- Animalia

However, this five-kingdom system is now considered by many to be outdated, and if one doesn't want to hyperinflate the number of kingdoms, one can use the three-domain system. These domains reflect whether cells have nuclei or not as well as differences in cell membranes / cell walls.

Archaea -- Eubacteria -- Eukaryota

The distinction between life and non-life is difficult, there is also a series of intracellular "parasites" that are progressively less alive in terms of being metabolically active:

Viruses -- Viroids -- Prions

Major Branches of Biology

Aerobiology -- Anatomy -- Astrobiology -- Biochemistry -- Bionics -- Biogeography -- Bioinformatics -- Biophysics-- Biotechnology -- Botany -- Cell biology -- Chorology -- Cladistics -- Cytology -- Developmental biology -- Ecology (Symbiology[?], Autecology[?])-- Ethology --Entomology-- Evolution (Evolutionary biology) -- Evolutionary developmental biology ("Evo-devo" or Evolution of Development) -- Freshwater Biology -- Genetics (Population genetics, Quantitative genetics[?], Genomics, Proteomics) -- Histology -- Immunology -- Infectious diseases -- Pathology -- Epidemiology -- Limnology -- Marine biology -- Microbiology (Bacteriology) -- Molecular Biology -- Morphology -- Mycology / Lichenology -- Neuroscience -- Oncology (the study of cancer) -- Ontogeny -- Paleontology (Palaeobotany[?], Palaezoology[?])-- Phycology (Algology) -- Phylogeny (Phylogenetics, Phylogeography[?]) -- Physiology -- Phytopathology -- Structural biology -- Taxonomy -- Toxicology (the study of poisons and pollution) -- Virology -- Zoology

Related Disciplines

Medicine -- Physical anthropology

People and History

Famous biologists -- History of biology[?] -- Nobel prize in physiology or medicine -- Timeline of biology and organic chemistry

What are our priorities for writing in this area? To help develop a list of the most basic topics in Biology, please see Biology basic topics.

External links and Resources

• Kimball's Biology Pages, http://www.ultranet.com/~jkimball/BiologyPages/ : An online searchable textbook.
• The Tree of Life, http://tolweb.org/tree/phylogeny.html : A multi-authored, distributed Internet project containing information about phylogeny and biodiversity.
• The Journal of Biology, http://www.jbiol.com : A small, but free, research journal
• BioCode, http://www.rom.on.ca/biodiversity/biocode/biocode1997.html : A proposal for organism naming

Books

• Lynn Margulis: Five Kingdoms: An Illustrated Guide to the Phyla of Life on Earth, 3rd ed., W H Freeman & Co 1998.
• Neil Campbell: Biology: Concepts and Connections, 3rd ed., Benjamin/Cummings 2000. A college-level textbook.