Organism

The bacterium Escherichia coli (E. coli), is a single-celled prokaryote
An amoeba is a single-celled eukaryote
Polypore fungi and angiosperm trees are large multicellular eukaryotes.
Precambrian stromatolites in the Siyeh Formation, Glacier National Park. In 2002, a paper in the scientific journal Nature suggested that these 3.5 Gya (billion years old) geological formations contain fossilized cyanobacteria microbes. This suggests they are evidence of one of the earliest known life forms on Earth.
LUCA may have used the Wood–Ljungdahl or reductive acetyl–CoA pathway to fix carbon.

Organism is any organic, living system that functions as an individual entity.

- Organism
The bacterium Escherichia coli (E. coli), is a single-celled prokaryote

48 related topics

Alpha

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Metabolic pathway

Linked series of chemical reactions occurring within a cell.

Linked series of chemical reactions occurring within a cell.

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Pathways are required for the maintenance of homeostasis within an organism and the flux of metabolites through a pathway is regulated depending on the needs of the cell and the availability of the substrate.

Theodor Schwann

German physician and physiologist.

German physician and physiologist.

Bronze statue of Theodor Schwann at the entrance of the Institute of Zoology, University of Liege, Belgium

Other contributions include the discovery of Schwann cells in the peripheral nervous system, the discovery and study of pepsin, the discovery of the organic nature of yeast, and the invention of the term metabolism.

The chemical elements ordered in the periodic table

Chemical element

A chemical element refers to all aspects of the species of atoms that have a certain number of protons in their nuclei, including the pure substance consisting only of that species.

A chemical element refers to all aspects of the species of atoms that have a certain number of protons in their nuclei, including the pure substance consisting only of that species.

The chemical elements ordered in the periodic table
Estimated distribution of dark matter and dark energy in the universe. Only the fraction of the mass and energy in the universe labeled "atoms" is composed of chemical elements.
Periodic table showing the cosmogenic origin of each element in the Big Bang, or in large or small stars. Small stars can produce certain elements up to sulfur, by the alpha process. Supernovae are needed to produce "heavy" elements (those beyond iron and nickel) rapidly by neutron buildup, in the r-process. Certain large stars slowly produce other elements heavier than iron, in the s-process; these may then be blown into space in the off-gassing of planetary nebulae
Abundances of the chemical elements in the Solar System. Hydrogen and helium are most common, from the Big Bang. The next three elements (Li, Be, B) are rare because they are poorly synthesized in the Big Bang and also in stars. The two general trends in the remaining stellar-produced elements are: (1) an alternation of abundance in elements as they have even or odd atomic numbers (the Oddo-Harkins rule), and (2) a general decrease in abundance as elements become heavier. Iron is especially common because it represents the minimum energy nuclide that can be made by fusion of helium in supernovae.
Mendeleev's 1869 periodic table: An experiment on a system of elements. Based on their atomic weights and chemical similarities.
Dmitri Mendeleev
Henry Moseley

Certain kinds of organisms require particular additional elements, for example the magnesium in chlorophyll in green plants, the calcium in mollusc shells, or the iron in the hemoglobin in vertebrate animals' red blood cells.

False-color Cassini radar mosaic of Titan's north polar region; the blue areas are lakes of liquid hydrocarbons. "The existence of lakes of liquid hydrocarbons on Titan opens up the possibility for solvents and energy sources that are alternatives to those in our biosphere and that might support novel life forms altogether different from those on Earth."—NASA Astrobiology Roadmap 2008

Hypothetical types of biochemistry

Hypothetical types of biochemistry are forms of biochemistry agreed to be scientifically viable but not proven to exist at this time.

Hypothetical types of biochemistry are forms of biochemistry agreed to be scientifically viable but not proven to exist at this time.

False-color Cassini radar mosaic of Titan's north polar region; the blue areas are lakes of liquid hydrocarbons. "The existence of lakes of liquid hydrocarbons on Titan opens up the possibility for solvents and energy sources that are alternatives to those in our biosphere and that might support novel life forms altogether different from those on Earth."—NASA Astrobiology Roadmap 2008
The Arecibo message (1974) sent information into space about basic chemistry of Earth life.
Structure of silane, analog of methane
Structure of the silicone polydimethylsiloxane (PDMS)
Marine diatoms – carbon-based organisms that extract silicon from sea water, in the form of its oxide (silica) and incorporate it into their cell walls
Artist's conception of how a planet with ammonia-based life might look
Titan's theorized internal structure, subsurface ocean shown in blue
Sulfuric acid (H2SO4)
Early stage of the genetic code (GC-Code) with "alanine world" and its possible alternatives.

Arsenic, which is chemically similar to phosphorus, while poisonous for most life forms on Earth, is incorporated into the biochemistry of some organisms.

Spinoloricus nov. sp., a metazoan that metabolises with hydrogen, lacking mitochondria and instead using hydrogenosomes.

Anaerobic organism

Spinoloricus nov. sp., a metazoan that metabolises with hydrogen, lacking mitochondria and instead using hydrogenosomes.
Aerobic and anaerobic bacteria can be differentiated by culturing them in test tubes of thioglycollate broth:
1: Obligate aerobes need oxygen because they cannot ferment or respire anaerobically. They gather at the top of the tube where the oxygen concentration is highest.
2: Obligate anaerobes are poisoned by oxygen, so they gather at the bottom of the tube where the oxygen concentration is lowest.
3: Facultative anaerobes can grow with or without oxygen because they can metabolize energy aerobically or anaerobically. They gather mostly at the top because aerobic respiration generates more adenosine triphosphate (ATP) than either fermentation or anaerobic respiration.
4: Microaerophiles need oxygen because they cannot ferment or respire anaerobically. However, they are poisoned by high concentrations of oxygen. They gather in the upper part of the test tube but not the very top. 5: Aerotolerant organisms do not require oxygen as they metabolize energy anaerobically. Unlike obligate anaerobes, however, they are not poisoned by oxygen. They can/will be evenly distributed throughout the test tube.

An anaerobic organism or anaerobe is any organism that does not require molecular oxygen for growth.

Through random drift or selection, lineage will trace back to a single person. In this example over 5 generations, the colors represent extinct matrilineal lines and black the matrilineal line descended from the mt-MRCA.

Most recent common ancestor

Through random drift or selection, lineage will trace back to a single person. In this example over 5 generations, the colors represent extinct matrilineal lines and black the matrilineal line descended from the mt-MRCA.

In biology and genetic genealogy, the most recent common ancestor (MRCA), also known as the last common ancestor (LCA) or concestor, of a set of organisms is the most recent individual from which all the organisms of the set are descended.

Crude oil, a transformed biogenic substance

Biogenic substance

Product made by or of life forms.

Product made by or of life forms.

Crude oil, a transformed biogenic substance
Natural gum, a secretion from Hevea brasiliensis
Biogenic sediment: limestone containing fossils
Model of movement of marine compounds
Oncolitic limestone: the spheroidal oncolites are formed via deposition of calcium carbonate by cyanobacteria
Chromatographic separation of chlorophyll
Cyanobacteria extracts inhibiting the growth of Micrococcus luteus
Photobioreactor used to produce microalgae metabolites
Scanning electron microscope image of silver nanoparticles
Chemical structure of lupeol, a triterpenoid derived from plants

An abiogenic substance or process does not result from the present or past activity of living organisms.

The light from the lamp (1.) functions as a detectable change in the plant's environment. As a result, the plant exhibits a reaction of phototropism--directional growth (2.) toward the light stimulus

Stimulus (physiology)

Detectable change in the physical or chemical structure of an organism's internal or external environment.

Detectable change in the physical or chemical structure of an organism's internal or external environment.

The light from the lamp (1.) functions as a detectable change in the plant's environment. As a result, the plant exhibits a reaction of phototropism--directional growth (2.) toward the light stimulus

The ability of an organism or organ to detect external stimuli, so that an appropriate reaction can be made, is called sensitivity (excitability ).