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Portal:Biology

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Introduction

A panoramic view from a ridge located between Segla and Hesten mountain summits in the island of Senja, Troms, Norway in 2014
A panoramic view from a ridge located between Segla and Hesten mountain summits in the island of Senja, Troms, Norway in 2014

Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that process hereditary information encoded in genes, which can be transmitted to future generations. Another major theme is evolution, which explains the unity and diversity of life. Energy processing is also important to life as it allows organisms to move, grow, and reproduce. Finally, all organisms are able to regulate their own internal environments.

Biologists are able to study life at multiple levels of organization, from the molecular biology of a cell to the anatomy and physiology of plants and animals, and evolution of populations. Hence, there are multiple subdisciplines within biology, each defined by the nature of their research questions and the tools that they use. Like other scientists, biologists use the scientific method to make observations, pose questions, generate hypotheses, perform experiments, and form conclusions about the world around them.

Life on Earth, which emerged more than 3.7 billion years ago, is immensely diverse. Biologists have sought to study and classify the various forms of life, from prokaryotic organisms such as archaea and bacteria to eukaryotic organisms such as protists, fungi, plants, and animals. These various organisms contribute to the biodiversity of an ecosystem, where they play specialized roles in the cycling of nutrients and energy through their biophysical environment. (Full article...)

Diagram of a typical prokaryotic cell

A prokaryote (/prˈkærit, -ət/; less commonly spelled procaryote) is a single-cell organism whose cell lacks a nucleus and other membrane-bound organelles. The word prokaryote comes from the Ancient Greek πρό (pró), meaning 'before', and κάρυον (káruon), meaning 'nut' or 'kernel'. In the two-empire system arising from the work of Édouard Chatton, prokaryotes were classified within the empire Prokaryota. However in the three-domain system, based upon molecular analysis, prokaryotes are divided into two domains: Bacteria (formerly Eubacteria) and Archaea (formerly Archaebacteria). Organisms with nuclei are placed in a third domain: Eukaryota.

Prokaryotes evolved before eukaryotes, and lack nuclei, mitochondria, and most of the other distinct organelles that characterize the eukaryotic cell. It was once thought that prokaryotic cellular components were unenclosed within the cytoplasm except for an outer cell membrane, but bacterial microcompartments, which are thought to be quasi-organelles enclosed in protein shells (such as the encapsulin protein cages), have been discovered, along with other prokaryotic organelles. While being unicellular, some prokaryotes, such as cyanobacteria, may form colonies held together by biofilms, and large colonies can create multilayered microbial mats. Others, such as myxobacteria, have multicellular stages in their life cycles. Prokaryotes are asexual, reproducing via binary fission without any fusion of gametes, although horizontal gene transfer may take place. (Full article...)

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The African bullfrog (Pyxicephalus adspersus) is a species of frog in the family Pyxicephalidae.

Major topics

History History of biology | timeline of biology and organic chemistry | history of ecology | history of evolutionary thought | history of geology | history of model organisms | history of molecular biology | history of paleontology
Overview Biology | science | life | properties (adaptationenergy processinggrowthorderregulationreproduction, and response to environment) | hierarchy of life (atommoleculeorganellecelltissueorganorgan systemorganismpopulationcommunityecosystembiosphere) | reductionistic | emergent property | mechanistic | scientific method | theory | law | peer review | biology journals
Chemical basis Matter | elements | compounds | atoms | molecules | chemical bonds | carbon | organic compounds | macromolecules | carbohydrate | protein | protein structure | protein folding | lipid | DNA | RNA
Cells Prokaryote | eukaryote | cell wall | cell membrane | cytoskeleton | mitochondrion | chloroplast | nucleus | endoplasmic reticulum | Golgi apparatus | cell cycle | mitosis | metabolism | cell signaling | protein targeting | metabolism | enzyme | glycolysis | citric acid cycle | electron transport chain | oxidative phosphorylation |photosynthesis |meiosis  | mitosis
Genetics (Intro) Classical genetics | mendelian inheritance | gene | phenotype | genotype | ploidy | alternation of generations | molecular genetics | gene expression | gene regulation | genome | karyotype | DNA replication | transcription | translation | recombination | chromosome | epigenetics | splicing | mutation | genetic fingerprint | chromatin | ecological genetics | population genetics | quantitative genetics
Evolution (Intro)  | omne vivum ex ovo | Natural selection | genetic drift | sexual selection | speciation | mutation | gene flow | evolution of sex | biogeography | cladistics | species | extinction | tree of life | phylogenies | three-domain system
Diversity Bacteria | archaea | plants | angiosperms | fungi | protists | Animals | deuterostome | insects | molluscs | nematodes | parasitism | Primate | mammal | vertebrate | craniata | chordate | viruses
Plant form and function Epidermis | flower | ground tissue  | leaf | phloem | plant stem | root | shoot | vascular plant | vascular tissue | xylem
Animal form and function Tissues | fertilization | embryogenesis | gastrulation | neurulation | organogenesis | differentiation | morphogenesis | metamorphosis | ontogeny  | Development | senescence  | reproduction | oogenesis | spermatogenesis
Ecology Ecosystem | biomass | food chain | indicator species | habitat | species distribution | Gaia theory | metapopulation  | life cycle | Life history | altricial - precocial | sex ratio | altruism | cooperation - foraging | learning | parental care | sexual conflict | territoriality | biosphere | climate change | conservation | biodiversity | nature reserve | edge effect | allee effect | corridor | fragmentation | pollution | invasive species | in situ - ex situ | seedbank
Research methods Laboratory techniques | Genetic engineering | transformation | gel electrophoresis | chromatography | centrifugation | cell culture | DNA sequencing | DNA microarray | green fluorescent protein | vector | enzyme assay | protein purification | Western blot | Northern blot | Southern blot | restriction enzyme | polymerase chain reaction | two-hybrid screening | in vivo - in vitro - in silico | Field techniques | Belt transect | mark and recapture | species discovery curve
Branches Anatomy | biotechnology | botany | cell biology | ecology | evolutionary biology | genetics | marine biology | microbiology | molecular biology | mycology | neuroscience | paleontology | phycology | physiology | protistology | virology | zoology
Awards Nobel Prize in Physiology or Medicine
See also Template:History of biology

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For the French Napoleonic War General see Marshall Étienne Macdonald


Marshall McDonald (October 18, 1835 – September 1, 1895) was an American engineer, geologist, mineralogist, pisciculturist, and fisheries scientist. McDonald served as the commissioner of the United States Commission of Fish and Fisheries from 1888 until his death in 1895. He is best known for his inventions of a number of fish hatching apparatuses and a fish ladder that enabled salmon and other migrating fish species to ascend the rapids of watercourses resulting in an increased spawning ground. McDonald's administration of the U.S. Commission of Fish and Fisheries was notably free of scandal and furthered the "protection and culture" of fish species throughout the United States. (Full article...)

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